Metocean Glossary
Metocean glossary is a dictionary that is authoritative reference to hydrographic related terms and definitions used in various standards, specifications and other informative referred in Maritime Industry. In Indonesian hydrography, The International Hydrographics Dictionary (S-32) is the main standards of terms and definition used.
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| ID | TERM | DEFINITION |
|---|---|---|
| 1 | Point | One thirty-second of a circle, or 11 1/4 degrees. Also called compass point when used in reference to compass directions. The extreme end of a cape; or the outer end of any land area protruding into the water, usually less prominent than a cape. In digital cartography, the 0-dimensional geometric primitive of an object that specifies location. [14] |
| 2 | Time | The measurable aspect of duration. The hour of the day reckoned by the position of a celestial reference point relative to a reference celestial meridian. An elapsed interval. [14] |
| 3 | Ice | The solid form of water. [14] |
| 4 | Surf | Collective term for breakers. The wave activity in the area between the shoreline and the outermost limit of breakers. [14] |
| 5 | Ria | A long narrow inlet, with depth gradually diminishing inward; a creek. Any broad river opening into the ocean. [14] |
| 6 | Gat | A natural or artificial passage or channel through shoals or steep banks, or across a line of banks lying between two channels. [14] |
| 7 | Wave | A disturbance which moves through or over the surface of the medium with speed dependent upon the properties of the medium. A ridge deformation, or undulation of the surface of a liquid. [14] |
| 8 | Light | A luminous or lighted aid to navigation. For internationally agreed abbreviations of light characteristics see the international chart specifications. [14] |
| 9 | Earth | The planet which we inhabit. The solid matter of the globe in distinction from water and air. The ground. [14] |
| 10 | Area | In united nations law of the sea terminology the seabed and ocean floor and subsoil thereof, beyond the limits of national jurisdiction. [14] |
| 11 | Plan | An orthographic drawing on a horizontal plane, as of an instrument, a horizontal section, or a layout. A large-scale map or chart of a small area. [14] |
| 12 | Chart | A special-purpose map generally designed for navigation or other purposes. See chart: nautical, paper. [14] |
| 13 | Phot | The unit of illumination in the cgs system. [14] |
| 14 | Position | Data which define the location of a point with respect to a reference system. The coordinates which define such a location. The place occupied by a point on the surface of the earth, or in space. [14] |
| 15 | Lane | An established route as an air lane or shipping lane. In an electronic radiolocation lattice, the zone between two lines on which measured values, expressed in terms of the system's electronic unit (wavelength or microsecond), are whole numbers and are one unit apart. See lattice. A lead. [14] |
| 16 | Tide | The periodic rise and fall of the surface of oceans, bays, etc., due principally to the gravitational interactions between the moon, sun, and earth. [14] |
| 17 | Survey | The orderly process of determining data relating to the physical or chemical characteristics of the earth. The act or operation of making measurements for determining the relative position of points on, above or beneath the earth's surface. The result of such operations. An organization for making surveys. [14] |
| 18 | Rate | In electronic navigation, the designation of pulse repetition rate for a pair of transmitting stations, their signals, and the resulting lines of position. [14] |
| 19 | Magnet | A body which produces a magnetic field around itself. It has the property of attracting certain materials capable of being magnetized. See heeling magnet. [14] |
| 20 | Direction | In surveying and mapping, the angle between a line or plane and an arbitrarily chosen reference line or plane. [14] |
| 21 | Rod | A unit of length equal to 5.5 yards or 16.5 feet. Also called perch or pole. A stadia or levelling rod. See also sounding pole. [14] |
| 22 | Horizon | In general, the apparent or visible junction of the earth and sky, as seen from any specific position. [14] |
| 23 | Sound | (v.i.). To measure the depth of the water. [14] |
| 24 | Sound | A relatively long arm of the sea forming a channel between an island and a mainland or connecting two larger bodies of water, as a sea and the ocean, or two parts of the same body but usually wider and more extensive than a strait. A vibratory disturbance in air or some other elastic medium, capable of being heard by the human ear, and thus of any frequency between about 20 and 20,000 cycles per second. [14] |
| 25 | Log | (v.t.). Said of a ship moving at a specified speed according to the indications given by the log. [14] |
| 26 | Log | An instrument for measuring the speed or distance or both travelled by a vessel. [14] |
| 27 | High | See anticyclone. [14] |
| 28 | Level | (v.t.). To make perfectly horizontal by means of a level. [14] |
| 29 | Level | A horizontal plane or line; especially, such a plane taken as a basis for the measurement of elevati-on. See sea level, mean sea level, half tide level, still water level. A level tract of land; a stretch of country approximately horizontal and unbroken by elevations. In surveying and levelling, either a spirit level or a levelling instrument. [14] |
| 30 | Pass | A break in a mountain range, permitting easier passage from one side of the range to the other; also called a col. A navigable channel leading to a harbor or river. Sometimes called passage. A narrow connecting channel between two bodies of water. [14] |
| 31 | Col | A marked depression in the summit line of a mountain chain, generally affording a pass from one slope to the other. In meteorology, a saddle-backed region of almost uniform pressure which appears between two depressions and two anticyclones arranged alternately in a cross. [14] |
| 32 | Meter | (1) a person who measures. (2) an instrument or apparatus for measuring. (3) a device for measuring a specified thing as in thermometer or barometer. See also metre. [14] |
| 33 | Current | Water or other fluid in essentially horizontal motion. In British terminology, a non-periodical movement of water, generally horizontally, due to many causes such as different temperatures and prevalent winds. Some may be temporary, others permanent. [14] |
| 34 | Wind | Air motion relative to the earth's surface. Unless it is otherwise specified, only the horizontal component is considered. [14] |
| 35 | Depth | The vertical distance from a given water level to the bottom. [14] |
| 36 | Station | Generally, a permanent or temporary location where scientific observations and measurements are made. In surveying, a point whose position has been (or is to be) determined. A station may be a marked station (i.e., a point permanently marked for recovery) or an unmarked station, one which is not recoverable. Also called survey station. [14] |
| 37 | Ram | The underwater projection of ice from an ice front, ice wall, iceberg, or floe. [14] |
| 38 | Port | A place provided with terminal and transfer facilities for loading and discharging cargo or passengers, usually located in a harbor. The left side of a craft, facing forward. The opposite is starboard. [14] |
| 39 | Sphere | A curved surface all points of which are equidistant from a fixed point within, called the center. [14] |
| 40 | Land | The solid portion of the earth's surface, as opposed to sea, water. A part of the earth's surface marked off by natural or political boundaries. [14] |
| 41 | Ocean | The vast body of water on the surface of the globe, which surrounds the land, the main or great sea. One of the main areas into which this body of water is divided geographically. [14] |
| 42 | Rig | A temporary, mobile structure, either fixed or floating, used in the exploration stages of oil and gas fields. [14] |
| 43 | Mark | One of the bits of leather, cloth, etc. Indicating a specified length of a lead line. A charted conspicuous object, structure, or light serving as an indicator for guidance or warning of a craft; a beacon. A definite object, such as an imprinted metal disk, used to designate a survey point and sometimes refers to the entire survey monument. Mark is used with a qualifying term such as station, reference, azimuth, or bench. See also benchmark and reference mark. [14] |
| 44 | EVA | Extreme value analysis (EVA) ; A statistical tool to estimate the likelihood of the occurrence of extreme values based on a few basic assumptions and observed/measured data. [7] |
| 45 | Navigation | The process of directing the movement of a craft from one point to another. [14] |
| 46 | Vertical | (Adj.). In the direction of gravity; perpendicular to the plane of the horizon. [14] |
| 47 | Vertical | (n.). The direction in which the force of gravity acts. A vertical line, plane, etc. [14] |
| 48 | Circle | In a surveying instrument, the graduated disk which is perpendicular to and centered about an axis of rotation and is calibrated to read the amount of rotation. [14] |
| 49 | Signal | As applied to electronics, any transmitted electrical impulse. That which conveys intelligence in any form of communication, such as a time signal, a pip on the scope of electronic equipment, or an object marking the location of a surveying station. [14] |
| 50 | Photograph | A general term for a positive or negative picture made with a camera on sensitized material or prints from such a camera original. [14] |
| 51 | Base | In a triangulation, the side of one of a series of connected triangles, the length of which is measured directly and with prescribed accuracy and precision, and from which the lengths of the other triangle sides are obtained by computation. Also called base line or triangulation base line. See also base terminals. [14] |
| 52 | Sun | The luminous celestial body at the center of the solar system, around which other celestial bodies revolve. [14] |
| 53 | Erg | The unit of energy or work in the cgs system. [14] |
| 54 | Scale | A series of marks or graduations at definite intervals. The ratio between the linear dimensions of a chart, map, drawing, etc., and the actual dimensions represented. It may be called chart scale or map scale when applied to a chart or a map. In photogrammetry, the ratio of a distance on a photo-graph to a corresponding distance on the ground. The scale of a photograph varies from point-to-point because of displacements caused by tilt and relief; but it is usually taken as f/h where f is the principal distance of the camera and h is the height of the camera above mean ground elevation. [14] |
| 55 | Range | Two or more objects in line. Such objects are said to be in range. An observer having them in range is said to be on the range. See also transit. Distance in a single direction or along a great circle. The extreme distance at which an object or light can be seen, or a signal detected or used. The distance a craft can travel without refueling, usually called cruising radius. The difference in extreme values of a variable quantity. [14] |
| 56 | Radio | Communication by electromagnetic waves, without a connecting wire. A radio receiver. Sometimes called wireless particularly in British terminology. [14] |
| 57 | Mount | A large hill or mountain, usually a detached, characteristically conical mass of earth. The term 'mount' is always used instead of mountain when it precedes a proper name. [14] |
| 58 | Height | the vertical distance of the top of an object affixed to the surface of the earth, measured from a specified datum usually a high-water datum. - 2. The vertical dimension of an object. Also called vertical length. [14] |
| 59 | Map | (v.t.). To prepare a map or engage in a mapping operation. [14] |
| 60 | Map | A representation (usually on a flat medium) of all or a portion of the earth or other celestial body, showing the relative size and position of features to some given scale or projection; also, a representation of all or part of the celestial sphere. A map may emphasize, generalize, or omit the representation of certain features to satisfy specific requirements. Maps are frequently categorized and referred to according to the type of information which they are primarily designed to convey, to distinguish them from maps of other types. [14] |
| 61 | Ground | The bottom of the sea. The solid surface of the earth. [14] |
| 62 | Ground | (v.t.). To touch bottom or run aground. See strand. [14] |
| 63 | Bottom | Any ground covered by water. [14] |
| 64 | Meridian | A north-south reference line, particularly a great circle through the geographical poles of the earth, from which longitudes (or departures) and azimuths are reckoned; or a plane normal to the geoid or spheroid defining such a line. The term usually refers to the upper branch. [14] |
| 65 | Fix | (v.t.). In hydrographic surveying, to determine, at regular intervals, the position of ships or boats, while sailing along a line of sounding. The usual method of fixing hydrographic surveys within sight of land is the three-point fix method. [14] |
| 66 | Period | The interval needed to complete a cycle. Any specified duration of time. [14] |
| 67 | Sounding | Measured or charted depth of water, or the measurement of such a depth. In meteorology, determination of one or several upper air meteorological elements by means of instruments carried up by balloon, aircraft, kite, glider, rocket, satellite, etc. [14] |
| 68 | Horizontal | (adj). Parallel to the plane of the horizon; perpendicular to the direction of gravity. [14] |
| 69 | Fix | In navigation, a relatively accurate position determined without reference to any former position. It may be classed as visual, celestial, electronic, etc., depending upon the means of establishing it. [14] |
| 70 | Buoy | A floating object moored to the bottom in a particular (charted) place, as an aid to navigation or for other specific purposes. Navigational buoys may be classified according to: (a) their shape, appearance, or construction, such as barrel, can, cask, conical, cylindrical, dan, keg, nun, pillar, spar, spherical, or top mark buoy; (b) their colour, such as black, cheque red, green, red buoy; (c) their location, such as bifurcation, fairway, junction, mid-channel, middle-ground, or turning buoy; (d) the various kinds of hazards or dangers to navigation which they mark, such as bar, isolated danger, fish trap, obstruction, spoil ground, telegraph or wreck buoy; (e) their particular purpose or use, such as anchor, anchorage, compass adjustment, dredging, farewell (or landfall), marker, quarantine, station (or watch), or warping buoy. [14] |
| 71 | Data | A representation of facts, concepts, or instructions in a formalized manner suitable for communication, interpretation, or processing. [14] |
| 72 | Axis | The line, real or imaginary, about which something centers or revolves. [14] |
| 73 | Temperature | The intensity or degree of heat. [14] |
| 74 | Tie | A survey connection from a point of known position to a point whose position is desired. A tie is made to determine the position of a supplementary point whose position is desired for mapping or reference purposes, or to close a survey on a previously determined point. To tie in is to make such a connection. The point to which the connection is made is termed a tie point. [14] |
| 75 | Image | The optical counterpart of an object. [14] |
| 76 | Mil | 1. 1/6400 of the circumference of a circle. Approximately 1/1000 radian. 2. 1/1000 of an inch. [14] |
| 77 | Error | The difference between an observed or computed value of a quantity and the ideal or true value of that quantity. [14] |
| 78 | Compass | An instrument consisting of two legs jointed by a pivot used for describing circles or transferring measurements. Also referred to as pair of compasses. An instrument for indicating a horizontal reference direction relative to the earth. [14] |
| 79 | Table | An orderly, condensed arrangement of numerical or other information, usually in parallel vertical columns. See conversion table, current tables, tide tables, traverse table. [14] |
| 80 | Observation | The act or practice of noting and recording facts and events as for some scientific study. The measure of a quantity whose value is desired. The data so noted and recorded. A single measure, at a single setting of an apparatus. [14] |
| 81 | Shore | The narrow strip of land in immediate contact with any body of water including the area between high and low water lines. [14] |
| 82 | Speed | Rate of motion. The terms speed and velocity are often used interchangeably, but speed is a scalar, having magnitude only, while velocity is a vector quantity, having both magnitude and direction. Speed may either be the ship's speed through water, or the speed made good over ground. [14] |
| 83 | Control | A system of points with established positions or elevations, or both, which are used as fixed references in positioning and correlating map features. Control is generally classified in four orders (with first order denoting highest quality) according to the precision of the methods and instruments used in establishing it, and the accuracy of the resultant positions and elevations. Often called basic control. Regulation or direction of a machine, electronic equipment, etc.; or the dial, knob, switch, etc. For performing this function. The exercise of directing influence over the movements of a craft or missile, with reference to changes in direction and speed. [14] |
| 84 | Echo | Reflected radiant energy. [14] |
| 85 | Gravity | That force which tends to pull bodies towards the earth; that is to give bodies weight. Gravity is the resultant of two opposing forces: gravitation and centrifugal force due to the rotation of the earth. [14] |
| 86 | Down | An area of high, treeless ground, usually undulating and covered with grass. See also dune. [14] |
| 87 | Plate | A thin, metal, plastic, or paper sheet, that carries the printing image and whose surface is treated to make only the image areas ink receptive. [14] |
| 88 | Disc | Rotating storage medium composed of one or two usable surfaces or a vertical assembly of such discs with a common axis. Typically, discs combine high storage volumes and short access time allowing fast access to data which is distributed randomly over the medium. [14] |
| 89 | Sextant | A double-reflecting instrument for measuring angles, primarily altitudes of celestial bodies. The sextant has an arc of 60°, a sixth of a circle, from which it derives its name, and a range of 120°. In modern practice the term also applies to a similar instrument, regardless of its range. See also octant, quadrant and quintan. [14] |
| 90 | Transit | In astronomy, the apparent passage of a star or other celestial body across a defined line of the celestial sphere, as a meridian, prime vertical, or almucantar. When no line is specified, a transit across the meridian is usually intended. See meridian transit. The apparent passage of a star or other celestial body across a line in the reticle of a telescope, or some line of sight. The apparent passage of a smaller celestial body across the disk of a larger celestial body. A surveying instrument composed of a horizontal circle graduated in circular measure and an alidade with a telescope which can be reversed in its supports without being lifted therefrom. Also, the act of making such a reversal. A theodolite having a telescope that can be transited in its supports is a transit and is sometimes termed a transit theodolite. All modern theodolites are transits. An astronomical instrument having a telescope which can be so adjusted in position that the line of sight may be made to define a vertical circle. A transit used in astronomical work is usually termed either an astro-nomic(al) transit or a transit instrument. In navigation, the position of two distant, fixed objects when they are in line to an observer; the line passing through them and the observer being a line of position. See also range. [14] |
| 91 | Lock | A wet dock in a waterway, permitting a ship to pass from one level to another. See tide lock. [14] |
| 92 | Second | The unit of time in the si system. A sixtieth part of a minute, an angle, or an arc. [14] |
| 93 | Ton | A unit of weight equal to 1,000 kilograms ('metric ton'), 2,240 pounds ('long ton'), or 2,000 pounds ('short ton'). [14] |
| 94 | Phase | The visible aspect of an object. The amount by which a cycle has progressed from a specified origin. In astronomy, any of the stages of variation in the illumination of the moon or a planet. See phase(s) of the moon. In physics, the state of aggregation of a substance, for example, solid (ice), liquid (water), or gas (vapor). [14] |
| 95 | Beacon | A fixed artificial navigation mark that can be recognized by its shape, colour, pattern, top mark or light character, or a combination of these. It may carry various additional aids to navigation. This term is not commonly used when the navigation mark can be classified as a lighthouse. [14] |
| 96 | Run | A brook, or small creek. The distance travelled by a craft during any given time interval, or since leaving a designated place. Complete performance of one programme on a computer. [14] |
| 97 | Crib | A permanent marine structure usually designed to support or elevate pipelines; especially a structure enclosing a screening device at the offshore end of a potable water intake pipe. The structure is commonly a heavy timber enclosure that has been sunken with rocks or other debris. [14] |
| 98 | Vent | The orifice through which molten lava reaches the crater of a volcano. Eventually it may become choked as the lava solidifies to form a plug or neck. [14] |
| 99 | Degree | A unit of angular or circular-arc measurement, equal to 1/360 of a circle. A unit of measurement of temperature in any scale. [14] |
| 100 | Parallax | An apparent displacement of the position of a body with respect to a reference point or system, caused by a shift in the point of observation. [14] |
| 101 | Fog | Suspension of very small water droplets in the air, generally reducing the horizontal visibility at the earth's surface to less than 1 kilometre. [14] |
| 102 | Cast | In oceanography, a single lowering of a series of water bottles or other oceanographic instruments at an oceanographic station. Also referred to as oceanographic cast. [14] |
| 103 | Flat | A level tract of land, as the bed of a dry lake or an area frequently uncovered at low tide. Usually in plural. [14] |
| 104 | Track | (v.t.). To follow the movements of an object as by radar or an optical system. To navigate by keeping a record, tabular or graphical of the past positions of a craft without regard for future positions. [14] |
| 105 | Track | The actual path or route of a craft over the ground or sea bottom, or its graphic representation. In air navigation also called track made good. [14] |
| 106 | Standard | An exact value (a physical entity or an abstract concept) established and defined by authority, custom, or common consent, to serve as a reference, model, or rule in measuring quantities or qualities, establishing practices or procedures, or evaluating results. In chart construction, a master copy of a chart upon which are marked all corrections affecting the chart between printings. [14] |
| 107 | Edge | In topography, the crest of a sharply pointed ridge. [14] |
| 108 | Front | N meteorology: a) surface of separation of two air masses (frontal surface); b) line of intersection of the surface of separation of two air masses with another surface or with the ground. [14] |
| 109 | Spheroid | An ellipsoid; a figure resembling a sphere. Also called ellipsoid or ellipsoid of revolution, from the fact that it can be formed by revolving an ellipse about one of its axes. In geodesy, this term is fre-quently used to mean reference spheroid. See also spheroid: oblate and spheroid: prolate. [14] |
| 110 | Name | The label of a numerical value used particularly to refer to the n (north) or s (south) label of latitude and declination. When latitude and declination are both n or both s, they are said to be of the same name, but if one is n and the others, they are said to be of contrary name. [14] |
| 111 | Channel | That part of a body of water (sometimes dredged) deep enough for navigation through an area otherwise not navigable. It is usually marked by a single or double line of buoys and sometimes by ranges. The deepest part of a stream, bay, or strait through which the main current flows. See also strait. [14] |
| 112 | Grid | A series of lines, usually straight and parallel, superimposed on a chart or plotting sheet to serve as a directional reference for navigation. See also graticule. Two sets of mutually perpendicular lines dividing a map, chart, or other representation of the earth's surface, into squares or rectangles to permit location of any point by a system of rectangular coordinates. In electronics, an electrode with one or more openings to permit passage of electrons or ions. [14] |
| 113 | Sand | Loose material consisting of small but easily distinguishable, separate grains, between 0.0625 and 2.000 millimeters in diameter. [14] |
| 114 | Group | A term distinguishing a light exhibiting two or more flashes or occultations from one exhibiting a single flash or single occultation. [14] |
| 115 | Longitude | Angular distance, along a primary great circle, from the adopted reference point. One of coordinates used to describe a position the other being latitude. [14] |
| 116 | Month | A measure of time based on the motion of the moon in its orbit. [14] |
| 117 | Tape | In surveying, a ribbon of steel, invar, or other suitable material on which graduations are placed for the measurement of lengths or distances. See also base tape (or wire). [14] |
| 118 | Hole | An abrupt hollow in the ground or ocean floor. See also passage. [14] |
| 119 | Clear | (v.t.). To make such distance from an object as to have open sea-room. [14] |
| 120 | Reach | A straight section of a river, especially a navigable river between two bends. See also sea reach. An arm of the sea extending into the land. [14] |
| 121 | Shallow | (Adj.). Having little depth. [14] |
| 122 | Shallow | (n.). An area composed of unconsolidated material where the depth of water is relatively slight. It may be a hazard to surface navigation. [14] |
| 123 | Thunder | Sharp or rumbling sound which accompanies lightning. [14] |
| 124 | Orbit | The path of a body or particle under the influence of a gravitational or other force. For instance, the orbit of a celestial body is its path relative to another body around which it revolves. In water waves, the path of a water particle affected by the wave motion. [14] |
| 125 | Density | In photography, a measure of the degree of blackening of an exposed film, plate or paper after development, or the direct image (in the case of a print-out material). It is defined strictly as the logarithm of the optical opacity. In oceanography, density is equivalent to specific gravity and represents the ratio, at atmospheric pressure, of the weight of a given volume of sea water to that of an equal volume of distilled water at 4.0°c. [14] |
| 126 | Rotation | Turning of a body about an axis within the body, as the daily rotation of the earth. See revolution. [14] |
| 127 | Component | See harmonic constituent. [14] |
| 128 | Tidal Current | See current. [14] |
| 129 | Beam | Radiant energy confined to a particular shape. [14] |
| 130 | Ais | See automatic identification system [14] |
| 131 | Iec | International electrotechnical commission [14] |
| 132 | Lag | The delay between change of condition and the indication of the change on an instrument. Delay in human reaction. The amount one cyclic motion is behind another, expressed in degrees. The opposite is lead. [14] |
| 133 | Great Circle | See circle. [14] |
| 134 | Slope | The deepening sea floor out from the shelf edge to the upper limit of the continental rise, or the point where there is a general decrease in steepness. [14] |
| 135 | Planet | A celestial body of the solar system, shining by reflected light and revolving around the sun. [14] |
| 136 | Negative | A photographic image on film, plate, or paper, in which the subject tones to which the emulsion is sensitive are reversed or complementary. [14] |
| 137 | Deviation | See deviation: magnetic. [14] |
| 138 | Telescope | An optical instrument used as an aid in viewing or photographing distant objects, particularly celestial objects. [14] |
| 139 | Gain | The ration of output voltage, current or power to input voltage, current, or power in electronic instruments. [14] |
| 140 | Heat | A form of energy transferred between systems by virtue of their temperature differences. [1] |
| 141 | Sample | A representative part or single item from a larger whole or group especially produced for inspection or to give evidence of quality. [14] |
| 142 | Accuracy | The extent to which a measured or enumerated value agrees with the assumed or accepted value. See precision. [14] |
| 143 | Word | An addressable subdivision of storage memory of a computer system. Usually an integer number of bytes (e.g., 4 bytes = 32 bit) indicating the standard length of number representation in storage. [14] |
| 144 | Cable | A unit of distance originally equal to the length of a ship's anchor cable, but now generally considered to be about 600 feet. In the British navy it is 608 feet, or exactly one-tenth of a nautical mile. In the united states navy, it is 720 feet but is infrequently used. Sometimes called cable length. A chain or very strong fibre or wire rope used to anchor or moor vessels or buoys. A stranded conductor or an assembly of two or more electric conductors insulated from each other, but laid up together with a strong, waterproof covering. [14] |
| 145 | Shoal | (Adj.). Shallow. [14] |
| 146 | Shoal | (n.). An offshore hazard to surface navigation with substantially less clearance than the surrounding area and composed of unconsolidated material. [14] |
| 147 | Shoal | (v.i.). To proceed from a greater to a lesser depth. To cause to become less deep. [14] |
| 148 | Sight | Observation of the altitude, and sometimes also the azimuth of a celestial body for a line of position, or the data obtained by such observation. Any of various devices used to aid the eyes in lining up an optical instrument on its objective. [14] |
| 149 | Climate | Fluctuating aggregate of atmospheric conditions characterized by the states and developments of the weather of a given area. [14] |
| 150 | Traverse | A method of surveying in which a sequence of lengths and directions of lines between points on the earth are obtained from field measurements and used in determining positions of the points. Also called survey traverse. [14] |
| 151 | Velocity | A vector quantity equal to speed in a given direction. [14] |
| 152 | Radiation | Emission or transfer of energy in the form of electromagnetic waves or particles. The energy itself is also termed radiant energy. [14] |
| 153 | Path | A line of movement; course taken, as the path of a meteor. A line connecting a series of points in space and constituting a proposed or travelled route. [14] |
| 154 | Celestial Body | Anybody pertaining to the heavens, constituting a unit for astronomical study, such as the sun, the moon, the planets, fixed stars, comets, etc. Also called heavenly body. [14] |
| 155 | Dam | A barrier to check or confine anything in motion; particularly one constructed to hold back water and raise its level to form a reservoir, or to prevent flooding. [14] |
| 156 | Dip | The vertical angle, at the eye of an observer between the horizontal and the line of sight to the apparent horizon. Also called dip of the horizon or depression of the horizon. The angle between the horizontal and the lines of forces of the earth's magnetic field at any point. Also called magnetic dip or magnetic inclination. [14] |
| 157 | Matte | Conglomerate of sand, mud and seaweed forming a shoal or reef. [14] |
| 158 | Island | A piece of land surrounded by water. [14] |
| 159 | Drawing | The graphic representation of data on a non-volatile medium. An impression following the printing of a nautical chart of either its black or its magenta detail on matte finish transparent plastic, used in revising subsequent printings of the chart. [14] |
| 160 | Contrast | In photography, the actual difference in density between the highlights and the shadows on a negative or positive. Contrast is not concerned with the magnitude of density but only with the difference in densities. Also, the rating of a photographic material corresponding to the relative density difference which it exhibits. [14] |
| 161 | Sediment | Particulate organic and inorganic matter which accumulates in a loose unconsolidated form. It may be chemically precipitated from solution, secreted by organisms, or transported by air, ice, wind, or water and deposited. [14] |
| 162 | Test | The hard covering or supporting structure of many invertebrates; it may be enclosed within an outer layer of living tissue; a shell. [14] |
| 163 | Clock | Instrument for measuring time and recording hours. [14] |
| 164 | Radian | The unit of plane angles in the si system. [14] |
| 165 | Acoustic | Science of sound, including its production, transmission, and effects. [14] |
| 166 | Magnetism | The ability to attract magnetic material, notably iron and steel. [14] |
| 167 | Thermometer | Instrument used in the measurement of temperature. [14] |
| 168 | Ebb | The ebb streams. Sometimes the term 'ebb' is also used with reference to vertical tidal movement. The opposite is flood. [14] |
| 169 | Power | See magnifying power. [14] |
| 170 | Heading | The direction in which a vessel or craft is pointed, usually expressed in degrees from north (true, magnetic, or compass) [14] |
| 171 | Passage | A narrow navigable channel, especially one through reefs or islands. [14] |
| 172 | Sailing | A method of solving the various problems involving course, distance, difference of latitude, difference of longitude and departure. The various methods are collectively spoken of as 'the sailings'. [14] |
| 173 | Harmonic | A sinusoidal quantity having a frequency that is an integral multiple of the frequency of a periodic quantity to which it is related. [14] |
| 174 | Positive | In photography, an image of the original object which corresponds to the same in the scheme of light and shade. [14] |
| 175 | Core | The central or innermost part of anything. See centrosphere. In oceanography, a vertical, cylindrical sample of the bottom sediments from which the nature and stratification of the bottom may be determined. Also, called core sample or sediment core. [14] |
| 176 | Crest | The highest part of a wave, swell, ridge, etc. [14] |
| 177 | Flood | The flood streams. Sometimes the term 'flood' is also used with reference to vertical tidal movement. The opposite is ebb. An overflowing of water on land usually dry; inundation. [14] |
| 178 | Minute | The sixtieth part of an hour; sixty seconds. The sixtieth part of a degree of arc; sixty seconds. [14] |
| 179 | Relief | The elevations or the inequalities, collectively, of a land surface; represented on a map or chart by contours, hypsometric tints, shading, spot elevations, hachures, etc. [14] |
| 180 | Deposit | Accumulations of solid material (of any type or from any source) on the sea bottom which eventually may become compacted and consolidated and form sedimentary rock. [14] |
| 181 | Computer | A person who performs calculations. A device capable of accepting data, processing it according to stored instruction that are followed in automatic sequence, and supplying the results in some form. It usually consists of input and output devices, storage, arithmetic and logical units, and a control unit. [14] |
| 182 | Junction | Place of meeting or joining, as that of a tributary with a main river, or of two channels in a waterway. In levelling, the place where two or more lines of levels are connected together. In hydrographic survey, the joining of two adjacent survey sheets. See overlap. [14] |
| 183 | Mountain | A natural elevation of the earth's surface rising abruptly from the surrounding level, and attaining an altitude which, relatively to adjacent elevations, is impressive or notable. [14] |
| 184 | Intersection | In surveying, the procedure of determining the horizontal position of an unoccupied point (intersec-tion station) by direction observations from two or more known positions. In photogrammetry, the procedure of determining the horizontal position of a point by intersecting lines of direction obtained photogrammetrically. The lines of direction may be obtained directly from vertical photographs or by graphic or mathematical rectification of tilted photographs. [14] |
| 185 | Dial | The face of a watch or clock. The clockwise face of an instrument for indicating, as by a moving pointer, the amount of something; face of a compass, gauge, or meter. A sundial. [14] |
| 186 | Mile | A unit of distance. See international nautical mile, sea mile, statute mile. [14] |
| 187 | Paper | For printing hydrographic charts, heavyweight, single layer paper is used. Such paper is generally made wholly or partly from rags and simulates hand-made paper. It is strong, moisture resistant and manufactured to withstand surface erasure. [14] |
| 188 | Signi | Abbreviation for signalization de navigation instruments. A system of buoyage used in certain inland waters in the Netherlands. [14] |
| 189 | Vector | Direct connection between two points, either given as two sets of coordinates (points), or by direction and distance from one given set of coordinates; or a point in a vector space defined by one set of coordinates relative to the origin of a coordinate system. [14] |
| 190 | Cyclone | See depression. [14] |
| 191 | Offshore | (Adj. And adv.). Away from the shore. [14] |
| 192 | Offshore | (n.). The comparatively flat zone of variable width which extends from the outer margin of the rather steeply sloping shoreface to the edge of the continental shelf. [14] |
| 193 | Navigational | (Adj.). See nautical. [14] |
| 194 | Bank | an elevation of the sea floor over which the depth of water is relatively shallow. [14] |
| 195 | Gyro | See gyroscope. [14] |
| 196 | Snow | Precipitation of ice crystals, most of which are branched (sometimes starshaped). [14] |
| 197 | Shelf | Geologically an area adjacent to a continent or around an island and extending from the low-water line to the depth at which there is usually a marked increase of slope towards greater depth. See also continental shelf. [14] |
| 198 | Spring | Spring tide. A natural issue of water or other substances from the earth. One on the bottom of the sea is called a submarine spring. [14] |
| 199 | Weight | The force with which a body is attracted by gravity. Any block or mass of material used for its heaviness. The relative value of an observation, source, or quantity when compared with other observations, sources, or quantities of the same or related quantities. The value determined by the most reliable method is assigned the greatest weight. [14] |
| 200 | Seaward | (Adj. And adv.). Away from the land; toward the sea. [14] |
| 201 | Gradient | The change of any quantity with distance in any given direction. See pressure gradient, temperature lapse rate. The amount of slope, inclination to the horizontal, in road, railway, etc. [14] |
| 202 | Leg | Each straight section of a traverse. One part of a craft's track consisting of a single course line. [14] |
| 203 | Hill | A small, isolated elevation, smaller than a mountain. See also knoll. [14] |
| 204 | Lake | A large body of water surrounded by land. [14] |
| 205 | Rift | A cleft, fissure, or chasm in the earth. See median valley. [14] |
| 206 | Zenith | The point where the direction of the plumb line produced above the horizon meets the celestial sphere. [14] |
| 207 | Astronomy | The science which deals with the size, constitution, motions, relative positions, etc. Of celestial bodies, including the earth. See also astrometry. [14] |
| 208 | Refraction | The process in which the direction of energy propagation is changed as the result of a change in density within the propagating medium, or as the energy passes through the interface representing a density discontinuity between two media. [14] |
| 209 | Straight Line | Mathematically the line of shortest distance between two points in a specified space or on a specified surface. [14] |
| 210 | Bay | Wide indentation in the coastline generally smaller than a gulf and larger than a cove. For the purposes of the united nations convention on the law of the sea, a bay is a well-marked indentation whose penetration is in such proportion to the width of its mouth as to contain land locked waters and constitute more than a mere curvature of the coast. See also historic bay. [14] |
| 211 | Card | See compass card. [14] |
| 212 | Lash | See lighter aboard ship. [14] |
| 213 | Moor | (v.t.). To secure a boat or other floating thing to a fixed object or the sea bottom. [14] |
| 214 | Tilt | The angle which anything makes with the horizontal. In photogrammetry, the angle at the perspective center between the photograph perpendicular and the plumb line, or other exterior reference direction; also, the dihedral angle between the plane of the photograph and the horizontal plane. [14] |
| 215 | Nadir | That point on the celestial sphere directly beneath the observer, and directly opposite to the zenith. [14] |
| 216 | Antenna | A conductor or system of conductors for radiating or receiving radio waves. Also called aerial. [14] |
| 217 | Pattern | See lattice. [14] |
| 218 | Sounder | A machine or apparatus for sounding. An echo sounder. [14] |
| 219 | Tornado | In north America, the name for an intense spout of large diameter. [14] |
| 220 | Boundary | Anything marking a limit; bound; border. [14] |
| 221 | Sea Floor | The bottom of the ocean and seas where there is a generally smooth gentle gradient. Also referred to as seabed (sometimes seabed or sea-bed), and sea bottom. [14] |
| 222 | Sea Water | The water of the seas, distinguished from fresh water by its appreciable salinity. The degree of the salinity greatly affects the water's physical characteristics. [14] |
| 223 | Magnetometer | An instrument for measuring the intensity and/or the direction of the earth's magnetic field. [14] |
| 224 | Etch | (v.t.). To form an image within the surface of a printing or drawing material by the use of solvents. [14] |
| 225 | Reef | A mass of rock or coral which either reaches close to the sea surface or is exposed at low tide, posing a hazard to navigation. [14] |
| 226 | Ridge | The linked major mid-oceanic mountain systems of global extent. Also called mid-oceanic ridge. [14] |
| 227 | Maritime | Bordering on, concerned with, or related to the sea. [14] |
| 228 | Original | See reproduction. [14] |
| 229 | Surround | See margin. [14] |
| 230 | Constituent | See harmonic constituent. [14] |
| 231 | Code | A method of information representation by mapping it into a machine-readable alphabet, e.g. Textual information may be represented in computer memory by the ascii or the ebcdic alphabet. [14] |
| 232 | Dock | The space between two piers. Also called a slip. [14] |
| 233 | List | Inclination to one side, as of a vessel until she has found equilibrium in an inclined position. Listing is a static condition, as distinguished from heeling which is dynamic. See heel. [14] |
| 234 | Chain | A group of transmitters broadcasting the same programme. In electronic navigation, several related transmitting stations in geographic proximity (decca chain, loran chain, etc.). In digital data, a sequence of one or more-line segments. [14] |
| 235 | Crust | In geology, the outer layer of the solid earth; the lithosphere. Also called earth's crust. [14] |
| 236 | Drift | (v.i.). To move by action of wind or current without control. [14] |
| 237 | Drift | The speed of the water due to ocean or tidal currents. A wide, slow-moving current principally caused by winds. The distance a craft is moved by current and wind. Drift angle or leeway. The term is also applied to any superficial deposit caused by a current of water or air. [14] |
| 238 | Strip | In ice terminology, a long narrow area of pack ice, about 1 km or less in width, usually composed of small fragments detached from the main mass of ice, and run together under the influence of wind, swell or current. [14] |
| 239 | Border | The district lying along the edge of a country or territory; a frontier. The boundary line which separates one country from another, the frontier line. [14] |
| 240 | Counter | An indicator on a machine, for keeping count of turns, strokes, etc., of the machine or its parts. [14] |
| 241 | Eclipse | The obscuration of a source of light by the intervention of an object. Whole or partial obscuration of a heavenly body by the interposition of another, or by the passing of one luminous heavenly body into the shadow of another. [14] |
| 242 | Equinox | One of the two points of intersection of the ecliptic and the celestial equator, occupied by the sun when its declination is zero. That point occupied on or about March 21, when the sun's declination changes from south to north, is called vernal equinox or first point of aries; that point occupied on or about September 23, when the declination changes from north to south, is called autumnal equinox or first point of libra. Also called equinoctial point. [14] |
| 243 | Receiver | One who or that which receives anything, particularly a radio receiver. [14] |
| 244 | Continent | One of the main continuous bodies of land on the earth's surface. The mainland, as distinguished from outlying islands, mainland. [14] |
| 245 | Reduction | The process of substituting for an observed value one derived therefrom. [14] |
| 246 | Thunderstorm | One or more sudden electrical discharges manifested by the flash of light (lightning) and a sharp or rumbling sound (thunder). [14] |
| 247 | Gal | (derived from galileo). The unit of acceleration in the cgs system. See milligal. [14] |
| 248 | Pip | See blip. [14] |
| 249 | Pile | a long heavy timber or section of steel, wood, concrete, etc., forced into the earth or sea floor to serve as a support, as for a pier, or to resist lateral pressure, or as a free standing pole within a marine environment. [14] |
| 250 | Till | Unstratified glacial drift consisting of clay, sand, gravel, and boulders intermingled in any proportions. Also called boulder clay. [14] |
| 251 | Beach | On a shore, the area on which the waves break and over which shore debris, such as sand, shingle, pebbles accumulate. A beach includes backshore and foreshore. [14] |
| 252 | Gauge | An instrument for measuring the size or state of anything. [14] |
| 253 | Needle | Short for magnetic needle. [14] |
| 254 | Seabed | See sea floor. [14] |
| 255 | Symbol | A character, letter, or similar graphic representation used on a chart, map, hydrographic survey sheet, or diagram to represent some object, quantity, characteristic, etc. [14] |
| 256 | Analysis | The drawing and interpretation of the patterns of various weather elements on a surface or upper-air chart. [1] |
| 257 | Exposure | In photography, the act of exposing a light-sensitive material to a light source. The total quantity of light received per unit area on a sensitized plate or film; may be expressed as the product of the light intensity and the exposure time. [14] |
| 258 | Salinity | A measure of the quantity of dissolved salts in sea water. It is normally defined as the total amount of dissolved solids in sea water in parts per thousand ( °) by weight when all the carbonate has been converted to oxide, the bromide and iodide to chloride, and all organic matter is completely oxidiz-ed. These qualifications result from the chemical difficulty in drying the salts in sea water. In practice, salinity is not determined directly but is computed from chlorinity, electrical conductivity, refractive index, or some other property whose relationship to salinity is well established. Because of the law of constancy of proportions, the amount of chlorinity in a sea water sample is used to establish the sample's salinity. The relationship between chlorinity cl and salinity s as set forth in Knudsen’s tables is s = 0.03 + 1.805 cl. A joint committee of IAPO, UNESCO, ICES, and SCOR proposed the universal adoption of the following equation for determining salinity from chlorinity: s = 1.80655 cl. It was adopted by IAPO in 1963 and ices in 1964. [14] |
| 259 | Spectrum | (pl. Spectra). A series of images formed when a beam of radiant energy is separated into its various wavelength components, as when a beam of white light is refracted and dispersed by a prism. The entire range of electromagnetic radiations, or any part of it used for a specific purpose, as the radio spectrum (10 kilohertz to 300,000 megahertz). [14] |
| 260 | Precision | The degree of refinement of a value not to be confused with accuracy, which is the degree of conformance with the correct value. [14] |
| 261 | Conjunction | In astronomy, the situation of two celestial bodies having the same celestial longitude or the same sidereal hour angle. For a superior planet, it occurs when the sun is between the earth and the planet. [14] |
| 262 | Frequency: Radio | Any frequency at which electromagnetic radiation of energy is useful for communication. Radio frequencies are usually classed as very low, below 30 kilohertz; low, 30-300 kilohertz; medium, 300-3,000 kilohertz; high, 3-30 megahertz; very high, 30-300 megahertz; ultra-high, 300-3,000 megahertz; super high, 3,000-30,000 megahertz; extremely high, 30,000-300,000 megahertz. [14] |
| 263 | Mud | Pelagic or terrigenous detrital material consisting mostly of silt and clay-sized particles (less than 0.06 millimeter) but often containing varying amount of sand and/or organic materials. It is a general term applied to any sticky fine-grained sediment whose exact size classification has not been determined. [14] |
| 264 | Stop | See aperture stop. [14] |
| 265 | Geoid | The figure of the earth considered as a mean sea level surface extended continuously through the continents. The actual geoid is an equipotential surface to which, at every point, the plumb line (direction in which gravity acts) is perpendicular. It is the geoid which is obtained from observed deflections of the vertical and is the surface of reference for astronomical observations and for geodetic levelling. See reference spheroid. [14] |
| 266 | Wreck | The ruined remains of a stranded or sunken vessel which has been rendered useless. See also dangerous wreck, and derelict. [14] |
| 267 | Radial | A straight line extending outward from a center. In photogrammetry, a line or direction from the radial center to any point on a photograph. The radial center is assumed to be the principal point, unless otherwise designated (e.g., nadir radial). See also isoradial. [14] |
| 268 | Overlap | In cartography and surveying, the amount by which one chart or survey sheet extends also over an adjoining chart or sheet. The amount by which different sets of survey data, obtained with the same system, cover the same area; customarily expressed as a percentage. [14] |
| 269 | Sea Ice | Any form of ice which has originated from sea water. Generally, any ice in the sea. [14] |
| 270 | Amplitude | In astronomy, the arc of the horizon, between a celestial body at rising or setting and true east or west point. In tide terminology, the semi-range of the harmonic constituent. In physics, the maximum departure of a wave or other periodic phenomenon from the average or zero position. [14] |
| 271 | Distortion | An undesired change in waveform. In optics, an aberration affecting the position of the images off the axis, in which objects at different angular distances from the axis undergo different magnifications. Also called lens distortion. In photography, any shift in the position of an image on a photograph which alters the perspective characteristics of the photograph. Causes of image distortion include lens aberration, differential shrinkage of film or paper, and motion of the film or camera. [14] |
| 272 | Inequality | A systematic departure from the mean value of a quantity. See annual inequality, diurnal inequality, lunar inequality, parallax inequality, phase inequality. [14] |
| 273 | Reflection | The process whereby a surface of discontinuity turns back a portion of the incident radiation into the medium through which the radiation approached. See surface reflection. [14] |
| 274 | Sea Bottom | See sea floor. [14] |
| 275 | Declination | In astronomy, the angle at the center of the celestial sphere between the radius passing through a celestial body and the plane of the celestial equator. Declination is measured by the arc of the hour circle between the celestial body and the celestial equator. It is plus when the body is north of the equator, and minus when south of it. [14] |
| 276 | Obstruction | In marine navigation, anything that hinders or prevents movement, particularly anything that endangers or prevents passage of a vessel. The term is usually used to refer to an isolated danger to navigation, such as a sunken rock or pinnacle. [14] |
| 277 | Precipitation | Phenomenon made up of an aggregate of aqueous particles, liquid or solid, crystallized, or amorphous, which fall from a cloud or group of clouds and reach the ground. [14] |
| 278 | Lee | That side towards which the wind blows; the sheltered side. [14] |
| 279 | Race | Swiftly flowing water in a narrow channel or river; also, the channel itself which may be artificial as in a mill-race. Also, a swift rush of water through a narrow channel in tidal waters and caused by the tidal movement of the waters. See tide race. [14] |
| 280 | Scan | See scope. [14] |
| 281 | Stone | A general term for rock and rock fragments ranging in size from pebbles and gravel to boulders or large rock masses. [14] |
| 282 | Watch | A small timepiece of a size convenient to be carried on the person. [14] |
| 283 | Mirror | Any surface which produces images by reflection of light rays. [14] |
| 284 | Target | Any object, point, etc., toward which something is directed. An object which reflects a sufficient amount of a radiated signal to produce an echo signal on detection equipment. See radar target, sonar target. The distinctive marking or instrumentation of a ground point to aid in its identification on a photograph. In photogrammetry, target designates a material marking so arranged and placed on the ground as to form a distinctive pattern over a geodetic or other control point marker, on a property corner or line, or at the position of an identifying point above an underground facility or feature. A target is also the image pattern on aerial photographs of the actual mark placed on the ground prior to photography. [14] |
| 285 | Diagram | A graphic representation of certain data. [14] |
| 286 | Humidity | Atmospheric water vapour content, expressed in any of several measures, such as relative humidity. [14] |
| 287 | Barometer | Instrument for measuring atmospheric pressure. [14] |
| 288 | Submerged | (Adj.). Under water; not showing above water. The opposite is uncovered. [14] |
| 289 | Tidal Day | Lunar day. The period of the daily cycle of the tides, differing slightly from the lunar day because of priming and lagging of the tide. [14] |
| 290 | Adjustment | The determination and application of corrections to observations or measurements, for the purpose of reducing errors or removing internal inconsistencies in observed results. Adjustment may either refer to mathematical procedures or to corrections applied to instruments. [14] |
| 291 | Visibility | The extreme horizontal distance at which prominent objects can be seen and identified by the unaided eye. [14] |
| 292 | Bore | A high breaking wave of water, advancing rapidly up an estuary. Bores can occur at the mouths of shallow rivers if the tide range at the mouth is large. They can also be generated in a river when tsunamis enter shallow coastal water and propagate up the river. Also called eager, mascaret, or tidal bore. [14] |
| 293 | Basin | a depression of the sea floor more or less equidimensional in plan and of variable extent. [14] |
| 294 | Plain | Any land with a flat or very slightly undulating surface. A flat, gently sloping or nearly level region of the sea floor, for example, abyssal plain. [14] |
| 295 | Platform | In geographical literature, a natural or artificial terrace; a flat elevated piece of ground; a tableland, a plateau. In oceanographic terminology, any man-made structure (aircraft, ship, buoy, or tower) from or on which oceanographic instruments are suspended or installed. Structures which are erected on or over the seabed and subsoil for the purpose of exploring for, developing, removing and transporting resources therefrom. [14] |
| 296 | Parameter | A quantity which remains constant within the limits of a given case or situation. [14] |
| 297 | Reckoning | In navigation, computation by which the position of a ship is found. See dead reckoning. [14] |
| 298 | Protractor | An instrument for measuring angles on a surface; an angular scale. In its most usual form, it consists of a circle or part of one (usually a semicircle) graduated in degrees. See protractor: three arm and compass rose. [14] |
| 299 | Aerial Photograph | See photography. [14] |
| 300 | Sue | The vertical amount which a vessel aground dries due to the fall of the tide. [14] |
| 301 | Dust | Any substance comminuted or pulverized, especially earth or other solid matter in a minute and fine state of subdivision, so that the particles are small and light enough to be easily raised and carried in a cloud by the wind. [14] |
| 302 | Inch | A unit of length equal to 1/12 of a foot or 2.54 cm. [14] |
| 303 | Noon | The instant at which a time reference is over the upper branch of the reference meridian. [14] |
| 304 | Soil | The earth or ground; the face or surface of the earth. The ground with respect to its composition, quality, etc., or as the source of vegetation. [14] |
| 305 | Scree | A mass of detritus, forming a precipitous, strong slope upon a mountainside. Also, the material composing such a slope. See also talus. [14] |
| 306 | Fixing | The process of rendering a developed photographic image permanent by removing the unaffected light-sensitive material. [14] |
| 307 | Margin | In cartography, that area of a map or chart lying outside the border. 'Margin' is preferred to the term 'surround'. [14] |
| 308 | Screen | A device to shield or separate one part of an apparatus from other parts, or to separate the effects of one part on others. In electronic charting, a device connected to a computer displaying information either under computer control, or under user control, e.g. On a cathode-ray tube. Devices allowing for high resolution are capable of displaying also graphics. [14] |
| 309 | Digital | A method of representing information by combinations of discrete and discontinuous data. [14] |
| 310 | Lightning | Luminous manifestations accompanying a sudden electrical discharge which takes place from or inside a cloud or, less often, from high structures on the ground or from mountains. [14] |
| 311 | Navigable | (Adj.). Affording passage to a craft; capable of being navigated. [14] |
| 312 | Depression | Any hollow or relatively sunken area. In meteorology, a region of the atmosphere in which the pressure is low relative to the surrounding region at the same level. It is represented on a weather chart by a system of isobars at a specified level or of contours at a specified pressure which enclose relatively low values of pressure or level. Also, called low or cyclone. [14] |
| 313 | Focal Plane | A plane parallel to the plane of a lens or mirror and passing through the focus. In photography, the plane (perpendicular to the axis of the lens) in which images of points in the object field of the lens are focused. [14] |
| 314 | Water Vapor | Water in the gaseous phase. [14] |
| 315 | Lunitidal Interval | The interval of time between the transit (upper or lower) of the moon over the local or Greenwich meridian and the next high water or low water at a place. The interval is assumed to be local unless otherwise specified. The average of all high-water intervals is called mean high water lunitidal interval, high water interval, or corrected establishment. The average of all low water intervals is called mean low water lunitidal interval, or low water interval. The expressions higher high-water interval, lower high water interval, higher low water interval, and lower low water interval are used when there is considerable diurnal inequality. See establishment. [14] |
| 316 | Lux | Unit of illumination in the si system. [14] |
| 317 | Berg | Short for iceberg. [14] |
| 318 | Cone | See fan. [14] |
| 319 | Knot | A division of the log line, by which the ship's speed is measured. A nautical unit of speed. One knot is one nautical mile per hour. The name is derived from the knots in the log line. [14] |
| 320 | Focus | (pl. Foci). That point at which parallel rays of light meet after being refracted by a lens or reflected by a mirror. Also called focal point. In seismology, the source of a given set of elastic waves. The true center of an earthquake, within which the strain energy is first converted to elastic wave energy. [14] |
| 321 | Focus | (v.t.). The process of adjusting an optical instrument, projector, cathode-ray tube, etc., to produce a clear and well-defined image. [14] |
| 322 | Globe | The earth; the world. A spherical structure on whose surface is depicted the geographical configuration of the earth (terrestrial globe). [14] |
| 323 | Pivot | A spindle or pin by which a movable part of an instrument is supported so as to be free to turn. The pivot of a compass is usually a fixed point on which the needle hangs by a single jeweled cap. [14] |
| 324 | Rhumb | See rhumb line. [14] |
| 325 | Sonar | A system of determining distance of an underwater object by measuring the interval of time between transmission of an underwater sonic or ultrasonic signal and the return of its echo. Direction may also be determined by noting the direction of transmission of the signal. The name sonar is derived from the words sound navigation and ranging. See echo ranging. [14] |
| 326 | Alidade | Pivoted sight bar that moves over a graduated arc. The upper part of a theodolite. The alidade used in topographic surveying consists of a straight-edge ruler carrying a telescope or other sighting device and used in recording a direction on the plane table sheet. The term is also used to describe a bearing circle fitted with a telescope to facilitate observation of bearings. If a telescope is used, the instrument is often termed a telescopic alidade. [14] |
| 327 | Display | A visual presentation of data. [14] |
| 328 | Air Mass | Ensemble of air particles whose paths and physical properties exhibit, in the horizontal, only small, and continuous differences. The mass may extend over an area of several million square miles and over a depth of several kilometers. [14] |
| 329 | Ecliptic | The great circle formed by the intersection of the plane of the earth's orbit around the sun (or apparent orbit of the sun around the earth) and the celestial sphere. [14] |
| 330 | Diurnal Inequality | The difference between the heights of the two high tides (high water inequality) or the two low tides (low water inequality) during a tidal day, or the difference in speed between the two flood or the two ebb currents during a tidal day. The average diurnal inequality is called tropic high-water inequality and tropic low water inequality when referred to the high waters and low waters, respectively, of tropic tides. Mean diurnal high-water inequality is half the average difference between the heights of the two high waters of each tidal day over a 19-year period. Mean diurnal low water inequality is half the average difference between the heights of the two low waters for a similar period. Also called declinational inequality. [14] |
| 331 | Node | A point that is the start or end point of a line segment. In astronomy, one of the two points of intersection of the orbit of a planet, planetoid, or comet with the ecliptic, or of the orbit of a satellite with the plane of the orbit of its primary. That point at which the body crosses to the north side of the reference plane are called the ascending node; the other, the descending node. The line connecting the nodes is called line of nodes. Also called nodal point. See regression of the nodes. In oceanography, that part of a standing wave where the vertical motion is least, and the horizontal velocities are greatest. See partial node. In optics, a nodal point. [14] |
| 332 | Pipe | A hollow metal tube, of varying diameters and lengths, imbedded in the bottom in a manner similar to a pile. Pipes are often used as privately maintained aids to navigation and in the determination of beach or bottom sand migration (deposition or erosion). [14] |
| 333 | Wash | The visible or audible motion of agitated water; especially that caused by the passage of a vessel. [14] |
| 334 | Otter | Plane surface towed forward of its middle length so that it will incline and dive. Used in fishing, minesweeping or surveying. See kite, kite otter, and Oropesa sweep. [14] |
| 335 | Scend | Upward motion of a vessel, either upward motion of the bow and stern associated with pitching or lifting of the entire vessel by waves or swell, when it may be called send. [14] |
| 336 | Arming | Tallow or other substance placed in the recess at the lower end of a sounding lead for obtaining a sample of the bottom. See bottom sample. [14] |
| 337 | Moment | The tendency or degree of tendency to produce motion about an axis. Numerically it is the quantity obtained by multiplying the force, speed, or mass, by the distance from the point of application or center of gravity to the axis. See magnetic moment. [14] |
| 338 | Mosaic | In photogrammetry, as assembly of aerial photographs whose edges usually have been torn, or cut, and matched to form a continuous photographic representation of a portion of the earth's surface. [14] |
| 339 | Carrier | See wave: carrier. [14] |
| 340 | Mooring | A place where a vessel may be secured. (usually in pl.) The equipment used to secure a vessel. The process of securing a vessel or oceanographic instruments other than anchoring with a single anchor. [14] |
| 341 | Network | In surveying, a pattern or configuration of stations called geodetic network. In geography, a complex system of rivers, canals, etc. In radio, a chain of transmitting radio stations owned and operated as a unit. [14] |
| 342 | Air Base | In photogrammetry, the line joining two air stations, or the length of this line; also, the distance (at the scale of the stereoscopic model) between adjacent perspective centers as reconstructed in the plotting instrument. See also photo base. [14] |
| 343 | Low Tide | See low water. [14] |
| 344 | Hurricane | Term, derived from a Caribbean word, first applied to tropical cyclones of the Caribbean sea. Wind with a speed equal to or greater than 58 knots. (Beaufort scale wind force 12.) [14] |
| 345 | Transport | The process by which a substance or quantity is carried past a fixed point, or across a fixed plane. In oceanography and meteorology, such quantities are: heat, momentum, mass, dissolved impurities, suspended particles, etc. [14] |
| 346 | Hour Angle | Angular distance west of a celestial meridian, the arc of the celestial equator, or the angle at the celestial pole, between the upper branch of a celestial meridian and the hour circle of a celestial body or the vernal equinox, measured westward through 24 hours (360o). It is usually further designated as local, Greenwich, or sidereal, as the origin of measurement is the local or Greenwich meridian, or the hour circle of the vernal equinox. [14] |
| 347 | Modulation | Variation of some characteristic of a wave, called the carrier wave, in accordance with instantaneous values of another wave, called the modulating wave. Variation of amplitude is amplitude modulation, variation of frequency is frequency modulation, and variation of phase is phase modulation. See modulation: pulse and modulation: space. [14] |
| 348 | Phenomenon | (pl. Phenomena). Any fact, circumstance, or experience that is apparent to the senses and that can be scientifically described or appraised; as, an eclipse is a phenomenon of astronomy. [14] |
| 349 | Sound Wave | See wave. [14] |
| 350 | Earth'S Magnetic Field | See geomagnetic field. [14] |
| 351 | Limb | The graduated curved part of an instrument for measuring angles, as that part of a marine sextant carrying the altitude scale, or arc. The circular outer edge of a celestial body. The half with the greatest altitude is called the upper limb and the half with the least altitude, the lower limb. [14] |
| 352 | Mole | A massive structure of masonry or large stones serving as a pier or breakwater, or both. Unit of quantity of matter in the si system. [14] |
| 353 | Cliff | Land rising abruptly for a considerable distance above the water or surrounding land. [14] |
| 354 | Coral | Hard calcareous skeletons of many tribes of marine polyps. [14] |
| 355 | Corer | A device for obtaining a core; a hollow tube that is driven into the ocean floor. Also called coring instrument or coring device. See corer: hydro plastic, corer: piston, piggot gun and vacuum lead. [14] |
| 356 | Input | What is put in, as electric current or other power put into a machine. Data to be transferred from an external storage medium, such as punched cards, into the internal storage of a computer. [14] |
| 357 | Shade | A coloured glass that can be moved into the line of sight of an optical instrument, such as a sextant, to reduce the intensity of light reaching the eye. Also, calledshade glass. See horizon shade, and index shade. [14] |
| 358 | Swell | Ocean waves which have travelled out of their generating area. Swell characteristically exhibits a more regular and longer period and has flatter crests than waves within their fetch. Rising of the water of a river above its usual level. Gently rising ground or a rounded hill above the surrounding ground. [14] |
| 359 | Fathom | A unit of length equal to 6 feet or 1.83 meters. [14] |
| 360 | Marker | That which marks something. A marker beacons. See also radio beacon. [14] |
| 361 | Master | An instrument which controls another similar instrument called a repeater. A master station. [14] |
| 362 | Output | The amount of power or energy produced by a machine. [14] |
| 363 | Trough | A long depression of the sea floor characteristically flat bottomed and steep sided and normally shallower than a trench. [14] |
| 364 | Valley | A long depression or hollow in the land lying between hills or stretches of high ground and usually having a river or stream flowing along the bottom. [14] |
| 365 | Buoyage | A system of, or providing with, buoys, serving the purpose of indicating navigable waters. See beaconage. [14] |
| 366 | Thermal | A small, rising parcel of warm air produced when the earth's surface is heated unevenly. [1] |
| 367 | Freezing | See frost. [14] |
| 368 | Sidereal | (Adj.). Of or pertaining to the stars. [14] |
| 369 | Solstice | One of the two points of the ecliptic farthest from the celestial equator; one of the two points on the celestial sphere occupied by the sun at maximum north or south declination. That in the northern hemisphere is called the summer solstice or first point of cancer, and that in the southern hemisphere, the winter solstice or first point of Capricorn. Also called solstitial point. That instant at which the sun reaches one of the solstices, about June 21 (summer solstice) or December 22 (winter solstice). [14] |
| 370 | Altimeter | An instrument that directly indicates the height above a reference surface. [14] |
| 371 | Anchorage | An area in which vessels anchor or may anchor. [14] |
| 372 | High Tide | See high water. [14] |
| 373 | Magnetize | (v.t.). To produce magnetic properties. The opposite is demagnetized. [14] |
| 374 | Magnitude | The importance, quality, or size of something. In astronomy, relative brightness of a celestial body. According to the accepted classification, a star of the 1st magnitude is a hundred times as bright as a star of the 6th magnitude (the faintest star that can be seen with the unaided eye) and the dis-tribution of magnitudes is logarithmic in terms of brightness. Thus, each reduction in magnitude means an increase of brightness of about 2 1/2. [14] |
| 375 | Mountains | On the sea floor, a well-delineated subdivision of a large and complex positive feature. See cordillera. [14] |
| 376 | Solar Day | See day. [14] |
| 377 | Wind Speed | Ratio of the distance covered by the air to the time taken to cover it. The 'instantaneous speed' or, more briefly, the 'speed', corresponds to the case of an infinitely small-time interval. The 'mean speed' corresponds to the case of a finite time interval. [14] |
| 378 | Compilation | in cartography, the selection, assembly, and graphic presentation of all relevant information required for the preparation of a map or chart, or a new edition or part thereof. Such information may be derived from other maps or charts, aerial photographs, surveys, new data, and other sources. In photogrammetry, the production of a map (or portion of a map) from aerial photographs and geodetic control data, by means of photogrammetric instruments. Sometimes called stereo compilation. [14] |
| 379 | Hour Circle | A great circle on the celestial sphere passing through the celestial poles. Also called declination circle, circle of declination, or circle of right ascension. [14] |
| 380 | Probability | The likelihood of an event measured by the ratio of the favorable cases to the whole number of cases possible. [14] |
| 381 | Mean Sea Level | The average height of the surface of the sea at a tide station for all stages of the tide over a 19-year period, usually determined from hourly height readings measured from a fixed predetermined reference level (chart datum). [14] |
| 382 | Atom | The smallest particle of an element which can enter into a chemical combination. [14] |
| 383 | Drag | (v.t.). To tow a line or object below the surface to determine the least depth in an area or to ensure that a given area is free from navigational dangers to a certain depth. See also sweep. To pull along the bottom, as an anchor. [14] |
| 384 | File | An entity of data for a specific task or purpose stored on a mass storage device. [14] |
| 385 | Horn | Fog signal using compressed air or electricity to vibrate a diaphragm. Horns exist in a variety of types which differ greatly in their sound and power. Further to the recent action taken by the hydrogra-pher of the United Kingdom. Such terms as nautophone, typhon and others are gradually being embraced by the general term 'horn'. [14] |
| 386 | Pull | An impression from an individual printing plate. [14] |
| 387 | Rips | A turbulent agitation of water generally caused by the interaction of currents and wind; in nearshore regions, rips may also be caused by currents flowing swiftly over an irregular bottom. [14] |
| 388 | Grade | Rate of slope or degree of inclination, as a 2% grade. See also gradient and grad. [14] |
| 389 | Heave | The oscillatory rise and fall of a ship due to the entire hull being lifted by the force of the sea. [14] |
| 390 | Hertz | A unit of frequency in the si system. See also cycle per second. [14] |
| 391 | Patch | In ice terminology, a collection of pack ice, less than 10 km across. [14] |
| 392 | Surge | A ship's bodily motion forward and backward along the longitudinal axis, caused by the force of the sea acting alternately on the bow and stern. The name applied to wave motion with a period intermediate between that of the ordinary wind wave and that of the tide, from about 1/2 to 60 minutes. Horizontal oscillation of water with comparative short period accompanying a seiche. [14] |
| 393 | Surge | (v.i.). To rise and fall, as a vessel at anchor. To vary abruptly and momentarily in amount, as an electric current in a circuit. [14] |
| 394 | Ashore | (Adj. And adv.). On the shore, on land or aground. [14] |
| 395 | Breeze | A wind of moderate strength. See land and sea (or lake) breeze. [14] |
| 396 | Stadia | A graduated rod used in the determination of distance by observing the intercept on the rod subtending a small known angle at the point of observation. In practice the angle is usually defined by two fixed lines in the reticle of a telescope. Also called stadia rod. [14] |
| 397 | Geodesy | The science which treats of the determination of the size and figure of the earth (geoid) by such direct measurements as triangulation, levelling and gravimetric observations. [14] |
| 398 | Glacier | A mass of snow and ice continuously moving from higher to lower ground or, if afloat, continuously spreading. The principal forms of glaciers are: ice sheets, ice shelves, ice caps, ice piedmonts, and various types of mountain glaciers. [14] |
| 399 | Lattice | A pattern formed by two or more families of intersecting lines, such as hyperbolic lines of position or parts of circles, drawn on charts, plotting sheets or sounding boards. [14] |
| 400 | Sinking | A downward movement of surface water generally caused by converging currents or when water mass becomes denser than the surrounding water. See upwelling, and convergence. An apparent lowering of distant terrestrial objects by abnormal atmospheric refraction. Because of sinking, objects normally visible at or near the horizon sometimes disappear below the horizon. The opposite is looming. [14] |
| 401 | Spatial | (Adj.). Pertaining to or limited by space. [14] |
| 402 | Response | For a device or system, the motion or other output resulting from an excitation or stimulus under special conditions. [14] |
| 403 | Routeing | A complex of measures concerning routes followed by ships and aiming at reducing the risk of casualties (traffic separation schemes, deep-draught routes, areas to be avoided, etc.). [14] |
| 404 | Twilight | The periods of incomplete darkness following sunset (evening twilight) or preceding sunrise (morning twilight). Twilight is designated as civil, nautical, or astronomical, as the darker limit occurs when the center of the sun is 6°, 12°, or 18° below the celestial horizon, respectively. [14] |
| 405 | Base Line | The line from which the outer limits of the territorial sea and certain other outer limits are measured. In radiolocation, the geodesic line between two stations operating in conjunction for the determination of a line of position. Also written as one word. See also base. [14] |
| 406 | Calibrate | V.t.). To fix, check or correct the graduations of a measuring instrument. To determine the calibre of. [14] |
| 407 | Coastline | The line where shore and water meet. Shoreline and coastline are generally used synonymously. [14] |
| 408 | Gyroscope | A rapidly rotating mass free to move about one or both axes perpendicular to the axis of rotation and to each other. It is characterized by gyroscopic inertia and precession. Sometimes shortened to gyro. [14] |
| 409 | Objective | See objective lens. [14] |
| 410 | Starboard | The right side of a craft facing forward. The opposite is port. [14] |
| 411 | Fog Signal | A warning signal transmitted by a vessel or aid to navigation during period of low visibility. Also, the device producing such a signal. [14] |
| 412 | Precession | Change in the direction of the axis of rotation of a spinning body, as a gyroscope, when acted upon by a torque. The direction of motion of the axis is such that it causes the direction of spin of the gyroscope to tend to coincide with that of the impressed torque. [14] |
| 413 | Topography | The configuration of the surface of the earth, including its relief, the position of its streams, roads, cities, etc. The earth's natural and physical features collectively. In oceanography, the term is applied to a surface such as the sea bottom or a surface of given characteristics within the water mass. [14] |
| 414 | Transducer | Any device for converting energy from one form to another (electrical, mechanical, or acoustic). [14] |
| 415 | Equilibrium | A state of balance between forces. [14] |
| 416 | Photography | The art or process of producing images on sensitized material through the action of light. [14] |
| 417 | Plane Table | A field device for plotting the lines of a survey directly from the observations. It consists essentially of a drawing board mounted on a tripod, with a ruler on which a telescope or other sighting device is mounted. See alidade. Also written as one word. [14] |
| 418 | Atmospheric Pressure | See pressure. [14] |
| 419 | Fan | A relatively smooth, fan-like depositional feature normally sloping away from the outer termination of a canyon or canyon system. Also called cone. [14] |
| 420 | Clay | Mineralogically, a hydrous aluminium silicate material with plastic properties and a crystal structure. As a size term, refers to sediment particles ranging from 0.0039 to 0.00024 millimeter, in which case it includes rock flour, calcareous muds, aragonite, etc. [14] |
| 421 | Gust | A sudden brief increase in the speed of the wind. [14] |
| 422 | Heel | Transverse inclination of a vessel due to the action of waves, wind, a greater weight on one side, etc. See also list. [14] |
| 423 | Mist | Suspension in the air of microscopic water droplets or wet hygroscopic particles, reducing the visi-bility at the earth's surface. [14] |
| 424 | Pier | A long, narrow structure extending into the water to afford a berthing place for vessels, to serve as a promenade, etc. See also jetty. [14] |
| 425 | Send | See scend. [14] |
| 426 | Vane | A device to indicate the direction from which the wind blows. Also called weathervane, wind vane. See anemometer. A sight on an instrument used for observing bearings, as on a pelorus, bearing circle, etc. Also called sight (or sighting) vane. A device to indicate the direction toward which the current flows. [14] |
| 427 | Ahead | Bearing approximately 000° relative. The term is often used loosely for dead ahead or bearing exactly 000° relative. The opposite is astern. [14] |
| 428 | Berth | Place in which a ship is moored at wharf. [14] |
| 429 | Epoch | A given period of time during which a series of related acts or events takes place. In astronomy, a particular instant for which certain data are given or at which an observation is made, and which then is usable as a reference point. [14] |
| 430 | Pilot | 1. A person who directs the movements of a vessel through pilot waters, usually a person who has demonstrated extensive knowledge of channels, aids to navigation, dangers to navigation, etc., in a particular area and is licensed for that area. 2. A book of sailing directions. [14] |
| 431 | Sweep | (v.t. & i.). To tow a line or object below the surface, to determine the least depth in an area or to ensure that a given area is free from navigational dangers to a certain depth; or the removal of such dangers. [14] |
| 432 | Swing | In photogrammetry, a rotation of a photograph in its own plane about its camera axis. [14] |
| 433 | Wharf | A structure serving as a berthing place for vessels. [14] |
| 434 | Afloat | Floating, as opposed to being aground. [14] |
| 435 | Astern | Bearing approximately 180° relative. The term is often used loosely for dead astern or bearing exactly 180° relative. The opposite is ahead. [14] |
| 436 | Bridge | 1. An elevated structure extending across or over the weather deck of a vessel, or part of such a structure. The term is sometimes modified to indicate the intended use, such as navigating bridge or signal bridge. 2. A structure erected over a depression or an obstacle such as a body of water, railroad, etc., to provide a roadway for vehicles or pedestrians. [14] |
| 437 | Dredge | (v.t.). To remove solid matter from the bottom of a water area. [14] |
| 438 | Dredge | An apparatus for bringing up solid material from the bottom of a water area, gathering deep water organisms, etc. A dredger. [14] |
| 439 | Anomaly | Deviation from the normal or natural characteristics of a phenomenon. Abnormality. In astronomy, true anomaly is the angle at the sun between lines connecting the sun with a planet and with the planet's perihelion. Mean anomaly and eccentric anomaly are also considered. [14] |
| 440 | Breaker | A wave breaking on the shore, over a reef, etc. Breakers may be roughly classified into three kinds, although the categories may overlap: spilling breakers break gradually over a considerable distance; plunging breakers tend to curl over and break with a crash; and surging breakers peak up, but then instead of spilling or plunging they surge up on the beach face. The french word 'brisant' is also used for the obstacle causing the breaking of the wave. [14] |
| 441 | Ellipse | A plane curve constituting the locus of all points the sum of whose distances from two fixed points, called foci, is constant. Also used to characterize errors in positions and measurements. [14] |
| 442 | Leeward | (Adj. And adv.). Toward the lee, or in the general direction toward which the wind is blowing. The opposite is windward. [14] |
| 443 | Release | A device for holding or releasing a mechanism, particularly the device by which the tangent screw of a sextant or surveying instrument is held in place or disengaged from the limb, or circle respectively. In oceanography acoustic releases are used to sever deployed instruments from their anchoring. [14] |
| 444 | Shutter | In photography, the mechanism of a camera which controls the length of time the emulsion is exposed. [14] |
| 445 | Infrared | (Adj.). Having a frequency immediately beyond the red end of the visible spectrum said of rays of longer wavelength than visible light, but shorter than radio waves. [14] |
| 446 | Pack Ice | Term used in a wide sense to include any area of sea ice, other than fast ice, no matter what form it takes or how it is disposed. Pack ice may be described as very open pack ice (1/10ths-3/10ths), open pack ice (4/10ths-6/10ths), close pack ice (7/10ths-9/10ths), very close pack ice (almost 10/10th with little if any water visible). [14] |
| 447 | Quadrant | A double-reflecting instrument for measuring angles. It is similar to a sextant, but has an arc of 90°. Also a surveying or astronomical instrument composed of a graduated arc about 90° in length, equipped with a sighting device. [14] |
| 448 | Terminal | A number of berths grouped together, providing facilities for handling a particular form of cargo, e.g. Oil terminal, container terminal. [14] |
| 449 | Windward | (Adj. And adv.). In the general direction from which the wind blows; in the wind; on the weather side. The opposite is leeward. [14] |
| 450 | Broadcast | Communication by radio intended for reception at any point within a specified area. [14] |
| 451 | Departure | The distance between two meridians at any given parallel of latitude expressed in linear units, usually nautical miles. The distance to the east or west made good by a vessel in proceeding from one point to another. [14] |
| 452 | Diaphragm | In a telescope, a thin glass disk on which etched lines forming a reticle are placed. See also reticle, and aperture stop. [14] |
| 453 | Light Ray | The geometrical concept of a single element of light propagated in a straight line and of infinitesimal cross-section; used in analytically tracing the path of light through an optical system. [14] |
| 454 | Stability | Property of the state of rest or continuous movement of a system such that any disturbance intro-duced into this state decreases. In meteorology, the term is often used as a synonym of static stability. [14] |
| 455 | Convection | In general, mass motions within a fluid resulting in transport and mixing of the properties of that fluid. In the atmosphere, organized internal motions within a layer of air, leading to vertical transport of heat, momentum, etc. [14] |
| 456 | Oscillator | A device for producing oscillations, especially one of the non-rotating type, as the sound generator of a sonic depth finder or a radio frequency generator. A submarine oscillator is a large, electrically-operated diaphragm horn which produces a sound for transmission through water. [14] |
| 457 | Rhumb Line | A line on the surface of the earth making the same oblique angle with all meridians; a loxodrome spiraling toward the poles in a constant true direction. Parallels and meridians, which also maintain constant true directions, may be considered special cases of the rhumb line. A rhumb line is a straight line on a Mercator projection. Sometimes shortened to rhumb. [14] |
| 458 | Solar Time | See time. [14] |
| 459 | Cartography | The art and science of expressing graphically, by maps and charts, the known physical features of the earth, or of another celestial body. Often includes the works of man and his varied activities. [14] |
| 460 | Chart Datum | See datum: chart. [14] |
| 461 | Chronometer | A portable timekeeper with a compensated balance, capable of showing time with extreme precision and accuracy. [14] |
| 462 | Depth Curve | A depth curve is a line connecting points of equal water depth which is sometimes significantly displaced outside of soundings, symbols, and other chart detail for clarity as well as generalization. Depth curves therefore often represent an approximate location of the line of equal depth as related to the surveyed line delineated on the source. [14] |
| 463 | Wave Height | The vertical distance between a crest and the preceding trough. [9] |
| 464 | Celestial Equator | See equator. [14] |
| 465 | MHW | Mean High Water (MHW) ; The average of all the high water heights observed. [21] |
| 466 | MLW | Mean Low Water (MLW) ; The average of all the low water heights observed. [21] |
| 467 | Belt | In ice terminology, a long area of pack ice from a few kilometers to more than 100 kilometers in width. [14] |
| 468 | Rime | A white or milky granular deposit of ice formed by the rapid freezing of supercooled water drops as they come in contact with an object in below-freezing air. [1] |
| 469 | Smog | Originally smog meant a mixture of smoke and fog. Today, smog means air that has restricted visibility due to pollution, or pollution formed in the presence of sunlight/photochemical smog. [1] |
| 470 | Marsh | A tract of low-lying land flooded at times and generally swampy. [14] |
| 471 | Pitch | The oscillations of a ship about the transverse axis, due to the bow and stern being raised or lowered on passing through successive crests and troughs of waves. Also called pitching. The distance along the axis of a screw or other helix between consecutive threads or ribs. The distance a propeller would advance longitudinally, in one revolution if there were no slip. [14] |
| 472 | Pound | A unit of mass, equal to 0.45359237 kilograms. [14] |
| 473 | Gnomon | Any object the shadow of which serves as an indicator, as the shadow pin of a sun compass. [14] |
| 474 | Pencil | In optics, a set of rays coming to or spreading out from a point. See light pencil. [14] |
| 475 | Strait | (also straits). A passage connecting two larger bodies of water. [14] |
| 476 | X-Rays | Electromagnetic radiation of the same nature as visible radiation but of an extremely short wavelength less than 10-2 micrometers. X-rays are used in radar technology. [14] |
| 477 | Drizzle | Fairly uniform precipitation composed exclusively of fine drops of water (diameter less than 0.5 mm), very close to one another. [14] |
| 478 | Drizzle | Small water drops between 0.2 and 0.5 mm in diameter that fall slowly and reduce visibility more than light rain. [1] |
| 479 | Hummock | A natural elevation of the earth's surface resembling a hillock, but smaller and lower. In ice terminology, a mound of ice raised by pressure. May be fresh or weathered. [14] |
| 480 | Opening | A break in a coastline or a passage through a reef, between shoals, etc. Any break in sea ice which reveals the water. [14] |
| 481 | Perigee | That orbital point nearest the earth when the earth is the center of attraction, as opposed to apogee. [14] |
| 482 | Plotter | An instrument used for plotting straight lines and measuring angles on a chart or plotting sheet. See protractor. In data processing it stands for (a) vector plotter: an electromechanical device for automatically drawing curves. The curves are generated by a sequence of linear incremental pieces ("vectors") depending on the resolution provided by the device. For cartographic purposes, high precision flat-bed plotters (drawing tables) are used. (b) raster or electrostatic plotter: a sophisticated electronic device for producing pictures by means of raster techniques. The picture is generated by lines of pixels drawn sequentially, typically with a resolution of 200-400 pixels per inch. Raster plotters can produce complete pictures in short time irrespective of the complexity of the picture's contents. [14] |
| 483 | Vernier | A short, auxiliary scale situated alongside the graduated scale of an instrument, by means of which fractional parts of the smallest division of the primary scale can be measured accurately. [14] |
| 484 | Eyepiece | In an optical device, the lens group which is nearest the eye and with which the image formed by the preceding elements is viewed. [14] |
| 485 | Geodesic | See geodesic line. [14] |
| 486 | New Moon | See phases of the moon. [14] |
| 487 | Open Sea | That part of the ocean not enclosed by headlands, within narrow straits, etc. See high sea. [14] |
| 488 | Pinnacle | Any high tower or spire-shaped pillar of rock or coral, alone or cresting a summit. It may extend above the surface of the water. It may or may not be a hazard to surface navigation. [14] |
| 489 | Repeater | A device for repeating at a distance the indications of an instrument or device. See compass repeater, gyro repeater, steering repeater. [14] |
| 490 | Lead Line | A line, graduated with attached marks and fastened to a sounding lead, used for determining the depth of water when making soundings by hand. Generally used in depths of less than 45 meters (25 fathoms). Lead lines are braided or left-laid. Also called sounding line. [14] |
| 491 | Mean Time | See time: mean solar. [14] |
| 492 | Shoreline | The line where shore and water meet. Although the terminology of coasts and shores is rather confused, shoreline and coastline are generally used as synonymous. [14] |
| 493 | Soft Iron | Iron or steel which is easily magnetized by induction, but loses its magnetism when the magnetic field is removed. The opposite is hard iron. [14] |
| 494 | Wire Drag | An apparatus for surveying rocky areas where normal sounding methods are insufficient to insure the discovery of all existing obstructions, pinnacles, rocks, etc., above a given depth or for determining the least depth of an area. It consists essentially of a buoyed wire towed at the desired depth by two launches. Often shortened to drag. See drag (v.t.). [14] |
| 495 | Conversion | Determination of the rhumb line direction of one point from another when the initial great circle direction is known, or vice versa. [14] |
| 496 | Ebb Stream | The horizontal movement of water associated with falling tide. Ebb streams generally set seaward, or in the opposite direction to the tide progression. Also called ebb, ebb current or outgoing stream. [14] |
| 497 | Fair Chart | (British terminology). The final, carefully made plot of a hydrographic survey. In contrast to the field board (boat sheet in US Terminology) which is a work sheet plotted during field operations from preliminary field data, the fair chart is plotted from corrected data and represents the official permanent record of that particular survey. Also called fair sheet. It is called smooth sheet in US Terminology. [14] |
| 498 | Graduation | The placing of marks on an instrument or device to represent standard values thereon. Also, the marks so placed. The division and subdivision of latitude and longitude shown on the borders of a chart. See also scale. [14] |
| 499 | Grid North | See north. [14] |
| 500 | Parametric | Characterizing a quantity which is influenced by the behavior of one or more parameters. [14] |
| 501 | Calibration | The act or process of determining certain specific measurements in an instrument or device by comparison with a standard, for the purpose of correcting or compensating errors or for purposes of record. [14] |
| 502 | Convergence | In oceanography, a situation whereby waters of different origins come together at a point or, more commonly, along a line known as a convergence line. Along such a line the denser water from one side sinks under the lighter water from the other side. See sinking. [14] |
| 503 | Evaporation | The process by which a liquid changes into a gas. [1] |
| 504 | Least Depth | The shoalest sounding value obtained on a feature. [14] |
| 505 | Storm Surge | A rise above normal water level on the open coast due only to the action of wind stress on the water surface. Storm surge resulting from a hurricane or other intense storm also includes the rise in level due to atmospheric pressure reduction as well as that due to wind stress. A storm surge is more severe when it occurs in conjunction with a high tide. Also called storm tide, storm wave, tidal wave. [14] |
| 506 | Thermocline | A vertical negative temperature gradient in some layer of a body of water, which is appreciably greater than the gradients above and below it; also a layer, in which such a gradient occurs. The principal thermoclines in the ocean are either seasonal, due to heating of the surface water in summer, or permanent. Also called discontinuity layer, or thermal layer. [14] |
| 507 | Projection: Stereographic | A perspective projection having the point of projection at the opposite end of the diameter of the sphere from the point of tangency of the plane of projection. It is conformal and is the only azimuthal projection having that quality. When the center of the projection is located at a pole of the sphere, it is called a stereographic polar projection; when on the equator, a stereographic meridional projection; and when on some other selected parallel of latitude, a stereographic horizon projection. Also called azimuthal orthomorphic projection. [14] |
| 508 | Dew | Deposit of water drops on objects at or near the ground, produced by the condensation of water vapor from the surrounding clear air. [14] |
| 509 | Alga | A plant of simple structure which grows chiefly in water, such as the various forms of seaweed. [14] |
| 510 | Hail | Precipitation of small balls or pieces of ice (hailstones) with a diameter ranging from 5 to 50 mm (0.2 to 2.0 in) or sometimes more, falling either separately or agglomerated into irregular lumps. [14] |
| 511 | Kite | A mechanical contrivance towed beneath the surface to warn of arrival in water of a certain depth. See submarine sentry. A contrivance for holding the inner end of an Oropesa sweep to the required depth. [14] |
| 512 | Loop | In oceanography, that part of a standing wave where the vertical motion is greatest and the horizon-tal velocities are least. Loops (sometimes called antinodes) are associated with clapotis and with seiche action resultant from resonant wave reflecting in a harbor or bay. [14] |
| 513 | Peak | A prominent elevation either pointed or of very limited extent across the summit. Also called pike. [14] |
| 514 | Post | A small beacon, more substantial than a perch, used for marking channels. See also pile. [14] |
| 515 | Canal | An artificial waterway with no flow, or a controlled flow, used for navigation or for draining or irrigating land (ditch). [14] |
| 516 | Mouth | The place of discharge of a stream into the ocean or entrance to a bay from the ocean. [14] |
| 517 | Proof | In cartography, an advanced copy of a map produced to check the design, register and/or to enable errors to be detected and corrected before final printing. [14] |
| 518 | Stake | An elongated wood or metal pole embedded in the bottom to serve as a marker or support for fish nets. [14] |
| 519 | Aurora | Luminous phenomenon which appears in the high atmosphere, mainly in high latitudes, in the form of rays, arcs, bands, draperies, or corona. Also called polar aurora. [14] |
| 520 | Debris | See detritus. [14] |
| 521 | Isobar | Line joining points of equal pressure on a given surface (level surface, vertical cross section, etc.). [14] |
| 522 | Mirage | Optical phenomenon consisting essentially of steady or wavering, single or multiple, upright or inverted, vertically enlarged or reduced, images of distant objects. [14] |
| 523 | Quartz | Crystalline silica. In its most common form it is colourless and transparent, but it takes a large variety of forms of varying degrees of opaqueness and colour. It is the most common solid mineral. Part of the ocean bed is composed of quartz. [14] |
| 524 | Shower | Precipitation, often short-lived and heavy, falling from convective clouds; the drops or solid particles in showers are usually bigger than the corresponding elements in other types of precipitation. Showers are characterized by their sudden beginning and ending, generally by large and rapid changes of intensity, and, most frequently, by the appearance of the sky; namely, rapid alternations of dark, menacing clouds (cumulonimbus) and of clearances of short duration. [14] |
| 525 | Summit | The highest point, part or elevation; top or apex. [14] |
| 526 | Abyssal | Belonging to the lowest depths of the ocean, generally below 3,700 meters (2,000 fathoms). [14] |
| 527 | Almanac | A periodical publication of astronomical data useful to a navigator. It contains less information than an ephemeris, and values are generally given to less precision. If information is given in a form and to a precision suitable for air navigation, it is called an air almanac. [14] |
| 528 | Geology | The science which has for its object the investigation of the earth's crust, of the strata which enter into its composition with their mutual relations, and of the successive changes to which their present condition and position are due. [14] |
| 529 | Ice Cap | See ice sheet. [14] |
| 530 | Sea-Bed | See sea floor [14] |
| 531 | Shading | Gradations of light, colour, or thickness of lines; or indications of shadows. Shading of lines is sometimes used on charts to produce the effect of height or depth. See also hill shading. [14] |
| 532 | Buoyancy | Force resulting from the upward pressure of water, acting upon the immersed volume of a body, set against the total weight of such body. If the volume immersed is such that the upward pressure counterbalances the weight of the body, the buoyancy is said to be positive and the body floats on the surface; if the volume immersed is insufficient, the weight of the body is greater than the upward pressure, the buoyancy is negative, and the body sinks. [14] |
| 533 | Coverage | The actual area covered (by charts, photographs, etc.). The area controlled by a radiolocation system. [14] |
| 534 | Entrance | The seaward end of a channel, harbor, dock, etc. [14] |
| 535 | Pendulum | A body so suspended from a fixed point as to swing freely to and from under the combined forces of gravity and momentum. A vertical bar so supported from below by a stiff spring as to vibrate to and for under the combined action of gravity and the restoring force of the spring. [14] |
| 536 | Recorder | The man on a survey party who records the observational data. A recording instrument. The part of an instrument or machine that records. [14] |
| 537 | Residual | See error: residual. [14] |
| 538 | Sampling | The process of taking samples. [14] |
| 539 | Software | All programs which can be used on a computer system. In particular the system software (i.e. The operating system) consists of all programs which are necessary for the proper functioning of the computer. The application software consists of all programs developed for special user applications. [14] |
| 540 | Sweeping | The process of towing a line or object below the surface, to determine whether an area is free from isolated submerged dangers to vessels and to determine the position of any dangers that exist, or to determine the least depth of an area. [14] |
| 541 | Temporal | (Adj.). Pertaining to or limited by time. [14] |
| 542 | Graticule | The network of lines representing meridians and parallels on a map, chart, or plotting sheet. See also grid. A scale at the focal plane of an optical instrument to aid in the measurement of objects. See also reticle. [14] |
| 543 | Reflector | A device capable of or intended for reflecting particles or radiant energy. See radar reflector. [14] |
| 544 | Sea State | Numerical scale of the average surface wave height as defined by the WMO code. Also called state of the sea. [14] |
| 545 | Boat Sheet | (US Terminology). The work sheet used by the hydrographer in the field for plotting the details of a hydrographic survey as it progresses. See also field board. [14] |
| 546 | Dip Circle | An instrument for measuring magnetic dip. It consists essentially of a dip needle or magnetic needle, suspended in such manner as to be free to rotate about a horizontal axis. Also called inclinometer, or dipping compass. See also earth inductor. [14] |
| 547 | Lapse Rate | The rate at which an atmospheric variable (usually temperature) decreases with height. (see environmental lapse rate.) [1] |
| 548 | Pollutants | Any gaseous, chemical, or organic matter that contaminates the atmosphere, soil, or water. [1] |
| 549 | True North | See north. [14] |
| 550 | Wave Crest | The highest part of a wave. [14] |
| 551 | Air Station | N photogrammetry, the point in space occupied by the camera lens at the moment of exposure. Also called exposure station or camera station. [14] |
| 552 | Camera Axis | See axis of camera. [14] |
| 553 | Datum Plane | A vertical control datum. Although a level surface is not a plane, the vertical control datum is frequently referred to as the datum plane. [14] |
| 554 | Gravitation | In general, the mutual attraction between masses of matter (bodies). Gravitation is the component of gravity which acts towards the earth. [14] |
| 555 | Large Scale | See scale. [14] |
| 556 | Photometeor | Optical phenomenon of the atmosphere. [14] |
| 557 | Electromagnetic Waves | Energy propagated in the form of electromagnetic waves. These waves do not need molecules to propagate them, and in a vacuum they travel at nearly 300,000 km per sec (186,000 mi per sec). See radiant energy. [1] |
| 558 | Calm | Wind with a speed zero or less than 2 knots (beaufort scale wind force 0). The state of sea when there are no waves. [14] |
| 559 | Cape | A piece of land projecting into a body of water. [14] |
| 560 | Gage | See gauge: tide. [14] |
| 561 | Rose | Name given to a compass card, or other diagram, having radiating lines. [14] |
| 562 | Scar | A lofty, steep face of rock upon a mountain-side; a precipice; cliff. [14] |
| 563 | Sill | A sea floor barrier of relatively shallow depth restricting water movement between basins. [14] |
| 564 | Silt | An unconsolidated sediment whose particles range in size from 0.0039 to 0.0625 millimeters in diameter (between clay and sand size). [14] |
| 565 | Awash | Adj. And adv.). Flush with, or washed by the waves. [14] |
| 566 | Fetch | An area of the sea surface over which seas are generated by a wind having a constant direction and speed. The length of the generating area, measured in the direction of the wind in which the seas are generated. [14] |
| 567 | Locus | (pl. Loci). All possible positions of a point or curve satisfying stated conditions. [14] |
| 568 | Noise | Any undesired sound. By extension, noise is any unwanted disturbance within a useful frequency band, such as undesired electric waves in a transmission channel or device. [14] |
| 569 | Scarp | The steep face of a hill. See also escarpment. [14] |
| 570 | Shell | The hard outside covering of an animal. Part of the ocean bed is composed of numerous shells of marine animals. [14] |
| 571 | Slave | A slave station. [14] |
| 572 | Title | In cartography, an inscription, on the chart or fair chart, including any useful information and details concerning the hydrographic survey, the natural scale, and geodetic, magnetic and tidal data. [14] |
| 573 | Cursor | A device used with an instrument, to provide a movable reference, as the runner of a slide rule, or the rotatable bearing indicator on a radar scope. In computer systems, a highlighted point on the display which indicates the actual working position. For graphical editing special cursors (e.g. Crosses, cross-hairs) can be selected. On output the cursor is moved automatically by the computer; on input it is under user control by means of a manual controlling device. A cursor may also be a manually positionable device, sometimes magnifying lens and a reticula to be used in connection with a digitizer. [14] |
| 574 | Freeze | A condition occurring over a widespread area when the surface air temperature remains below freezing for a sufficient time to damage certain agricultural crops. A freeze most often occurs as cold air is advected into a region, causing freezing conditions to exist in a deep layer of surface air. Also called advection frost. [1] |
| 575 | Lagoon | An enclosed area of salt or brackish water separated from the open sea by some more or less effec-tive, but not complete, obstacle such as low sand bank. The name most commonly used for the area of water enclosed by a barrier reef or atoll. [14] |
| 576 | Pascal | The unit of pressure in the si system. [14] |
| 577 | Piling | A group of piles set in a row. [14] |
| 578 | Rocket | In hydrography or navigation, a pyrotechnic projectile used for signaling, or for life-saving purposes. [14] |
| 579 | Draught | See draft. [14] |
| 580 | Erosion | The general process of the wearing away of rocks and soil at the earth's surface by natural agencies. [14] |
| 581 | Iceberg | A large mass of floating or stranded ice broken away from a glacier or from an ice shelf. Often of considerable height (in any case more than 5 m above the level of the sea). [14] |
| 582 | Inshore | (Adj. And adv.). Near or towards the shore. [14] |
| 583 | Landing | A place where boats receive or discharge passengers, freight, etc. [14] |
| 584 | Profile | A graph or curve showing elevation or distribution of some property vs. Distance along a line. The vertical scale may be greatly exaggerated with respect to the horizontal scale. An example of a profi-le is the graphic record made by a recording echo sounder operating while a vessel is underway. A vertical section of the surface of the ground, or of underlying strata, or both, along any fixed line. [14] |
| 585 | Snapper | A bottom sampling device used to collect a small amount (less than 1 pint) of material from the ocean floor. It has metal jaws that snap shut when the device touches the bottom. Also called clam shell snapper. [14] |
| 586 | Storage | In a computer, a device in which data can be inserted and preserved, and from which data can be retrieved. Common storage devices are magnetic tapes, drums, disks and cores. [14] |
| 587 | Terrain | Standing ground. A tract of country considered with regard to its natural features, configuration, etc. [14] |
| 588 | Emulsion | In photography, a suspension of a salt of silver in gelatine or collodion, used to coat plates, films, or papers. [14] |
| 589 | Fast Ice | Sea ice which remains fast, generally in the position where originally formed, and which may attain a considerable thickness. It is found along coasts, where it is attached to the shore, or over shoals, where it may be held in position by islands, grounded icebergs or grounded polar ice. [14] |
| 590 | Millibar | A unit of pressure equal to 1/1,000 of a bar. The millibar is much used in meteorology. [14] |
| 591 | Momentum | Quantity of motion. That property of a particle which is given by the product of its mass with its velocity. [14] |
| 592 | Monument | (US Terminology). In surveying, a structure used or erected to mark the position of a station; permanence is implied. [14] |
| 593 | Resurvey | A retracing on the ground of the lines of an earlier survey, in which all points of the earlier survey that are recovered are held fixed and used as a control. If too few points of the earlier survey are recovered to satisfy the control requirements of the resurvey, a new survey may be made. A resurvey is related directly to an original survey although several resurveys may interpose between them. [14] |
| 594 | Swath(E) | The strip or lane on the ground or sea floor scanned by the swath(e) sounding system when the survey platform proceeds along its course. [14] |
| 595 | Clearance | In navigation, a safe distance off a danger. In meteorology: a) decrease of total cloud amount when the latter is large; b) time at which this decrease takes place; c) gap in a cloud layer covering the entire sky. Also called clearing. [14] |
| 596 | Ephemeris | A statement presenting positions and related data for a celestial body for given epochs (dates) at uniform intervals of time. Also a publication containing such data for a number of celestial bodies. See also almanac: air and almanac: nautical. [14] |
| 597 | Gas Field | An area in which natural gas occurs in quantities worthy of exploitation. [14] |
| 598 | Hand Lead | See lead. [14] |
| 599 | Hyperbola | An open curve with two parts, all points of which have a constant difference in distance from two fixed points called foci. [14] |
| 600 | Ice Sheet | A continuous mass of ice and snow of considerable thickness and large area. Ice sheets may be resting on rock (see inland ice sheet) or floating (see ice shelf). Ice sheets of less than 40,000 sq. Km resting on rock are called ice caps. [14] |
| 601 | Indicator | That part of electronic equipment in which the data obtained by the receiver is presented for visual observation. This is usually in the form of a scope or dial. [14] |
| 602 | Intercept | The name given in marcq St. Hilaire method to the difference between the calculated altitude and the true altitude of a celestial body. Also called altitude difference. [14] |
| 603 | Isocentre | The unique point common to the plane of a photograph, its principal plane, and the plane of an assumed truly vertical photograph taken from the same camera station and having an equal principal distance. The point of intersection on a photograph of the true principal line and the isometric parallel. The point on a photograph intersected by the bisector of the angle between the plumb line and the photograph perpendicular. The isocenter is significant because it is the center of radiation for displacements of images caused by tilt. [14] |
| 604 | Messenger | In oceanographic terminology, a cylindrical metal weight, usually hinged and with a latch so that it can be fastened around a wire, and sent down to actuate water bottles and current meters after they have been lowered to the desired depth. [14] |
| 605 | Neat Line | Line, usually grid or graticule, bounding the detail of a map. Also referred to as inner neat line to differentiate from border drawn outside of neat line. Also written as one word. [14] |
| 606 | Omnirange | A radio aid to navigation providing direct indication of the magnetic bearing (omnibearing) of that station from any direction. Also called omnidirectional range or omnidirectional beacon. [14] |
| 607 | Projector | An optical instrument which throws the image of a negative or print upon a screen or other viewing surface, usually at a larger scale. An underwater acoustic transmitter. See underwater sound projector. [14] |
| 608 | Si System | See systems international. [14] |
| 609 | Sound Ray | A line perpendicular at each of its points to the fronts of a sound wave. [14] |
| 610 | Sub-Point | That point on the surface of the earth at which a particular celestial body is in the zenith at a specified time. Also called 'geographical position of a celestial body'. Called sub-celestial point in canadian terminology. See sublunar point, subsolar point, substellar point. [14] |
| 611 | Vibration | Periodic motion of an elastic body or medium in alternately opposite directions from equilibrium; oscillation. The motion of a vibrating body during one complete cycle; two oscillations. [14] |
| 612 | Anchor Ice | Ce which is attached to the bottom, irrespective of the nature of its formation. Also called bottom ice, depth ice, ground ice, lappened ice and underwater ice. [14] |
| 613 | Collimator | An optical device for artificially creating a target at infinite distance (a beam of parallel rays of light) used in testing and adjusting certain optical instruments. It usually consists of a converging lens and a target (a system or arrangement of cross hairs) placed at the principal focus of the lens. [14] |
| 614 | Hydrophone | An electroacoustic transducer that responds to water-borne sound waves and delivers essentially equivalent electric waves. See also pressure hydrophone. [14] |
| 615 | Plumb Line | The line of force in the geopotential field. The continuous curve to which the direction of the normal gravity is everywhere tangential. [14] |
| 616 | Quadrature | An elongation of 90° usually specified as east or west in accordance with the direction of the body from the sun. The moon is at quadrature at first and last quarters. See phases of the moon. The situation of two periodic quantities differing by a quarter of a cycle. [14] |
| 617 | Scale: Bar | A graduated line on a map, plan, photograph, or mosaic, by means of which actual ground distances may be determined. Also called graphic scale or linear scale. [14] |
| 618 | Scattering | In physics, the change in direction of a particle or wave, because of a collision with another particle or system. In electromagnetism, diffusion of electromagnetic waves in a random manner by air masses in the upper atmosphere. See also: tropospheric scattering. [14] |
| 619 | Tide Gauge | See gauge. [14] |
| 620 | Turbulence | A state of fluid flow in which the instantaneous velocities exhibit irregular and apparently random fluctuations, so that in practice only statistical properties can be recognized and submitted to analysis. Superimposed on the mean motion of the air, an agitation composed of air motions which are uncoordinated and in a state of continuous change. [14] |
| 621 | Wave Front | The leading side of a wave. [14] |
| 622 | Bathymetric | (Adj.). Of or pertaining to bathymetry. [14] |
| 623 | Field Board | (British terminology). Wooden board, or zinc or plastic sheet, used by hydrographers and land surveyors for plotting and recording the details of the survey in the field. Separate boards are usually prepared for topography and sounding respectively. The former are referred to as topography boards; the latter as sounding boards. See also boat sheet, and plane table. [14] |
| 624 | Image Point | In photogrammetry, the image on a photograph corresponding to a definite object on the ground. [14] |
| 625 | Inclination | The angle which a line or surface makes with the vertical, horizontal or with another line or surface. [14] |
| 626 | Instability | Property of the state of rest or continuous movement of a system such that any disturbance intro-duced into this state grows. In meteorology, the term is often used as a synonym of static instability. [14] |
| 627 | Slack Water | The interval when the speed of the tidal current is very weak or zero; usually refers to the period of reversal between ebb and flood currents. Also called slack tide. [14] |
| 628 | Tidal Datum | See datum. [14] |
| 629 | Trade Winds | Persistent winds, mainly in the lower atmosphere, which blow over vast regions from a subtropical anticyclone toward the equatorial regions. The predominant directions of the trade winds are from ne in the northern hemisphere and from se in the southern hemisphere. [14] |
| 630 | True Course | See course. [14] |
| 631 | Celestial Coordinates | See coordinates. [14] |
| 632 | Apex | The top, peak, or highest point of something, as of a mountain. See also vertex. [14] |
| 633 | Berm | A narrow, raised path or embankment along a stream, canal, or beach. On a beach it may be formed by the deposit of material by waves and marks the limit of high tides. [14] |
| 634 | Boom | A floating barrier used to protect a river or harbor mouth or to create a sheltered area for storage purposes. [14] |
| 635 | Byte | A unit consisting of 8 bits, frequently used for measuring the capacity of storage devices. 1 Kbyte = 210 byte = 1.024 byte (kilo-byte); 1 Mbyte = 220 byte = 1.048.576 byte (mega-byte); 1 Gbyte = 230 byte = 1.073.741.824 byte (giga-byte). [14] |
| 636 | Drum | A rotating cylinder on which is set a registering card or paper for recording purposes. Cylinder around which cable is wound in a winch. [14] |
| 637 | Eddy | A circular movement of water usually formed, where currents pass obstructions, between two adjacent currents flowing counter to each other, or along the edge of a permanent current. [14] |
| 638 | Foul | (1) to entangle or become entangled; e.g. As a propeller becoming entangled in cables, nets, or seaweed. (2) to attach or come to lie on the surface of submerged objects, usually in large numbers or amounts as barnacles on the hull of a ship. [14] |
| 639 | Isle | An island. Now more usually applied to an island of smaller size, except in established appellation, as the 'British isles'. [14] |
| 640 | Kelp | One of an order of usually large blade-shaped or vinelike brown algae. [14] |
| 641 | Lava | The fluid or semi-fluid matter flowing from a volcano. The substance that results from the cooling of the molten rock. Part of the ocean bed is composed of lava. [14] |
| 642 | Loom | The glow of a light which is below the horizon, caused by reflection by solid particles in the air. Vague first appearance of land at sea. [14] |
| 643 | Pool | A small body of still or standing water, permanent or temporary; chiefly one of natural formation. A deep or still place in a river or stream. In ice terminology, any enclosed relatively small area in pack ice, drift ice, other than a lead. See polynia. [14] |
| 644 | Ruin | A ruin is a structure in a decayed or deteriorated condition resulting from neglect or disuse, or a damaged structure in need of repair. A ruin is considered hazardous if it extends over or into navigable waters and thus represents a danger to surface navigation. [14] |
| 645 | Slip | See dock. [14] |
| 646 | Beset | (Adj.). Of a ship when surrounded so closely by sea ice that steering control is lost. The term does not imply pressure. See also icebound, nipped. [14] |
| 647 | Brook | A small stream; a rivulet. Also called run. [14] |
| 648 | Comet | A heavenly body having a starlike nucleus with a luminous foggy envelope (see coma), and usually developing a long luminous tail when near the sun. [14] |
| 649 | Diver | A person skilled in the practice of diving. [14] |
| 650 | Fault | In geology, a break of shear in the earth's crust with an observable displacement between the two sides of the break, and parallel to the plane of the break. [14] |
| 651 | Gauss | The cgs unit of magnetic induction. [14] |
| 652 | Haven | An enclosed and protected harbor. [14] |
| 653 | Inset | In cartography: a) a small area outside the neat lines of a map or chart included within the neat lines or borders to avoid publishing a separate graphic of the small area alone; b) a representation of a small area on a larger scale (e.g., town-plan inset), or of a large area at a smaller scale (e.g., orientati-on inset); c) any information, not normally appearing within the geographic limits of a map, which has been enclosed by border lines and included within the map neat lines. Insets are always placed in areas where important features will not be obscured. [14] |
| 654 | Invar | An alloy of nickel and steel which has a low coefficient of expansion. [14] |
| 655 | Ledge | A shelf-like projection, on the side of a rock or mountain. A rocky formation continuous with and fringing the shore. [14] |
| 656 | Magma | The molten material in a state of fusion under the crust of the earth from which igneous rocks are formed. [14] |
| 657 | Pixel | Contraction for "picture element". The smallest element resolvable by electronic raster devices such as scanner, display, and plotter. See remote sensing. [14] |
| 658 | Racon | A radar beacon which returns a coded signal which provides identification of the beacon as well as range and bearing. The range and bearing are indicated by the location of the first character received on the radar ppi scope. The name 'racon' is derived from the words radar beacon. [14] |
| 659 | Slush | An accumulation of ice crystals which remain separate or only slightly frozen together. It forms a thin layer and gives the sea surface a greyish or leaden-tinted colour. With light winds no ripples appear on the surface. [14] |
| 660 | Spire | A pointed structure extending above a building. The spire is seldom less than two‘ thirds of the entire height and its lines are rarely broken by stages or other features. The term is not applied to short pyramid-shaped structures rising from a tower or belfry. [14] |
| 661 | Spout | Phenomenon consisting of an often violent whirlwind, revealed by the presence of a cloud column or inverted cloud cone (funnel cloud), protruding from the base of a cumulonimbus and of a 'bush' composed of water drops raised from the surface of the sea or of dust, sand, or litter, raised from the ground. [14] |
| 662 | Swamp | An area of spongy land saturated with water. It may have a shallow covering of water, usually with a considerable amount of vegetation appearing above the surface. [14] |
| 663 | Apogee | That orbital point farthest from the earth when the earth is the center of attraction, as opposed to perigee. [14] |
| 664 | Binary | The number system using 2 as the base for number representation. Binary numbers are composed of bits. Generally any element capable of only two mutually exclusive states is called binary. [14] |
| 665 | Comber | A deep water wave whose crest is pushed forward by a strong wind and is much larger than a whitecap. Also called beach comber. A long-period spilling breaker. See also roller. [14] |
| 666 | Filter | In optics, any transparent material which, by absorption, selectively modifies the light transmitted through an optical system. In ocean-wave forecasting, a set of formulas that define the particular wave frequencies and directions in the fetch area which are of significance at the point of forecast. [14] |
| 667 | Hollow | Trough or depression between crests of sea-waves. A cavity or hole. [14] |
| 668 | Launch | Large open or half decked boat. [14] |
| 669 | Ripple | The ruffling of the surface of water, hence a little curling wave or undulation. A wave controlled to a significant degree by both surface tension and gravity. [14] |
| 670 | Roller | An indefinite term, sometimes considered to denote one of a series of long-crested, large waves which roll in upon a coast, as after a storm. Large breakers on exposed coasts formed by swell coming from a great distance. See comber. [14] |
| 671 | Runway | A defined rectangular area, on a land aerodrome, prepared for the landing and take-off run of aircraft along its length. [14] |
| 672 | Sludge | Spongy whitish ice lumps, a few centimeters across; they consist of slush, of snow slush and some-times of spongy ice lumps formed on the bottom of the sea and emerging on the surface. [14] |
| 673 | Squall | Atmospheric phenomenon characterized by a very large variation of wind speed: it begins suddenly, has a duration of the order of minutes, and decreases rather suddenly in speed. It is often accom-panied by a shower or thunderstorm. (WMO classification squall requires wind speed to increase by at least 8m/s, top speed of at least 11m/s, and lasting at least 1 minute in duration) [14] |
| 674 | Strand | (v.t. & i.). To run aground. The term strand usually refers to a serious grounding, while the term ground refers to any grounding, however slight. [14] |
| 675 | Tripod | A three-legged stand for theodolite, camera, signals, etc. [14] |
| 676 | Uprush | The rush of water up onto the beach following the breaking of a wave. See run-up. [14] |
| 677 | Zodiac | The band of the sky extending 8.5° either side of the ecliptic. The sun, moon, and navigational planets are always within this band, with the occasional exception of Venus. The zodiac is divided into 12 equal parts, called 'signs', each part being named for the principal constellation originally within it. [14] |
| 678 | Aground | Touching, resting or lodged on the bottom of shallow water. The opposite is afloat. [14] |
| 679 | Blunder | See error: gross. [14] |
| 680 | Caisson | A steel structure used for closing the entrance of locks, wet and dry docks. See also lock gate. [14] |
| 681 | Culture | All features constructed on the surface of the earth by man, such as cities, railways, canals, etc. [14] |
| 682 | Cumulus | A cloud in the form of individual, detached domes or towers that are usually dense and well defined. It has a flat base with a bulging upper part that often resembles cauliflower. Cumulus clouds of fair weather are called cumulus humilis. Those that exhibit much vertical growth are called cumulus congestus or towering cumulus. [1] |
| 683 | Fairway | That part of a river, harbor etc. Where the main navigable channel for vessels of larger size lies. It is also the usual course followed by vessels entering or leaving harbors and sometimes called ship channel . [14] |
| 684 | Looming | An apparent elevation of distant terrestrial objects by abnormal atmospheric refraction. Because of looming, objects below the horizon are sometimes visible. The opposite is sinking. The appearance indistinctly of an object during a period of low visibility. [14] |
| 685 | Navarea | The short title for a geographical sea area (may include inland seas, lakes and waterways navigable by sea-going ships) established for the purpose of coordinating the broadcast of navigational warnings. The term navarea followed by a roman numeral may be used to identify a particular sea area. The delimitation of such areas is not related to and shall not prejudice the delimitation of any boundaries between states. [14] |
| 686 | Outflow | The flow of water from the river or its estuary to the sea. Total volume for any given period of time. [14] |
| 687 | Pelorus | A compass card in the form of a metal plate mounted in gimbals to maintain a horizontal position and fitted with sight-vanes for observing bearings where direct use of the compass for this purpose is impracticable. Also called dumb compass or bearing plate. See also alidade. [14] |
| 688 | Plateau | A flat or nearly flat elevation of considerable areal extent, dropping off abruptly on one or more sides; a tableland. [14] |
| 689 | Plummet | A sounding lead. A plumb bob. [14] |
| 690 | Subsoil | All naturally occurring matter lying beneath the sea-bed or deep ocean floor. [14] |
| 691 | Tsunami | A long-period sea wave produced by a submarine earthquake or volcanic eruption. It may travel unnoticed across the ocean for thousands of miles from its point of origin. It builds up to great heights over shoal water. Also called tsunami, tidal wave, seismic sea wave. [14] |
| 692 | Aerosols | Tiny suspended solid particles (dust, smoke, etc.) Or liquid droplets that enter the atmosphere from either natural or human (anthropogenic) sources, such as the burning of fossil fuels. Sulfur-containing fossil fuels, such as coal, produce sulfate aerosols. [1] |
| 693 | Asteroid | One of the many small planets revolving around the sun, most of the orbits being between those of mars and jupiter. Also called planetoid or minor planet. [14] |
| 694 | Dry Dock | See dock. [14] |
| 695 | Envelope | In electronics, a graph defining the variations in amplitude of successive oscillations in an amplitude-modulated wave. [14] |
| 696 | Guidance | The exercise of directing influence over the movements of a craft or missile with particular refe-rence to the selection of a flight path. [14] |
| 697 | Ice Edge | The boundary at any given time between the open sea and sea ice of any kind, whether drifting or fast. [14] |
| 698 | Inmarsat | A company providing mobile satellite communications. The only company (2011) providing services within the gmdss. [14] |
| 699 | Land Ice | See glacier ice. [14] |
| 700 | Log Line | A graduated line used to measure the speed of a vessel through the water or to measure the speed of a current from a vessel at anchor. The line secured to a log. See current pole. [14] |
| 701 | Obscured | (Adj.). Said of the arc of a light sector designated by its limiting bearings in which the light is not visible from seaward. [14] |
| 702 | Pipeline | A string of interconnected pipes used for the transport of matter, nowadays mainly oil or gas . [14] |
| 703 | Scribing | A method of preparing a map by cutting the lines into a prepared coating. [14] |
| 704 | Streamer | A string of hydrophones towed behind a ship. [14] |
| 705 | Tracking | The process of observing the sequential changes in the position of a target to establish its motion. [14] |
| 706 | Uncovers | See covers and uncovers. [14] |
| 707 | Accretion | The gradual building up of land over a long period of time, solely by the action of the forces of nature, on a beach by deposition of water or air-borne material. Artificial accretion is a similar build-up of land by reason of an act of man. Also called aggradation. [14] |
| 708 | Alignment | The placing of objects along a straight line. In navigation, the bringing into line of two or more conspicuous objects, such as lights, beacons, etc. Also their bearing as seen by an observer from seaward. [14] |
| 709 | Astrolabe | An instrument formerly used for measuring altitudes of celestial bodies. See astrolabe: prismatic. [14] |
| 710 | Date Line | The line coinciding approximately with the 180th meridian, at which each calendar day first begins, the boundary between the -12 and +12 time zones. The date on each side of this line differs by one day, but the time is the same in these two zones. Sometimes called calendar line or international date line. [14] |
| 711 | Full Moon | See phases of the moon. [14] |
| 712 | Heliostat | An instrument composed of one or more plane mirrors, so mounted and arranged that a beam of sunlight may be reflected by it in any desired direction and kept there by continuous adjustment. It is used in geodetic surveying for reflecting a beam of sunlight from a station towards another distant station, where it can be observed with a theodolite. Also called heliotrope, or Galton’s sun signal. [14] |
| 713 | High Seas | The open sea beyond the exclusive economic zone, the territorial sea or the archipelagic waters of an archipelagic state. [14] |
| 714 | Ice Cover | See ice concentration. [14] |
| 715 | Interface | A surface, usually plane, forming the boundary between adjacent solids, spaces or immiscible liquids. In data processing it describes all information (signals, data) and the specifications ("protocol") required for exchanging data between two units of a system. Interfaces exist between hardware and software units but also between computer and human user. [14] |
| 716 | Lightship | A distinctively marked vessel anchored or moored at a charted point, to serve as an aid to navigation. By night it displays a characteristic light(s), and is usually equipped with other devices, such as a fog signal, submarine sound signal, and radio beacon, to assist navigation. Also called light vessel. [14] |
| 717 | Microwave | A very short radio wave, usually 30 cm to 0.3 mm. [14] |
| 718 | Polar Low | Depression that forms in polar air, often near a boundary between ice and sea. [15] |
| 719 | Resection | The graphical or analytical determination of a position as the intersection of at least three lines of known relative direction to corresponding points of known position. In photogrammetry, the determination of the position and/or attitude of a camera, or the photograph taken with that camera, with respect to the exterior coordinate system. [14] |
| 720 | Roadstead | An area near the shore, where vessels can anchor in safety; usually a shallow indentation in the coast. Also called road or roads. See open roadstead. [14] |
| 721 | Wave: Sky | An indirect radio wave which travels from the transmitting antenna into the sky, where the ionosphere bends it back toward the earth. Also called ionospheric wave. See wave: ground. [14] |
| 722 | Zone Time | See time. [14] |
| 723 | Cold Front | Any non-occluded front which moves in such a way that colder air replaces warmer air. [14] |
| 724 | Coral Reef | A reef, often of large extent, composed chiefly of coral and its derivatives. [14] |
| 725 | Degaussing | Neutralization of the strength of the magnetic field of a vessel, by means of suitably arranged electric coils permanently installed in the vessel. See also cable: degaussing. [14] |
| 726 | Earthquake | A shaking or trembling of the crust of the earth caused by underground volcanic forces or by breaking and shifting of rock beneath the surface. [14] |
| 727 | Elongation | The angular distance of a body of the solar system from the sun. The angle at the earth between lines to the sun and another celestial body of the solar system. The term is usually used in connection with inferior planets. The greatest elongation of such a body is its maximum angular distance from the sun, as observed from the earth. The position of a star when its azimuth east or west of the meridian is greatest. [14] |
| 728 | Fish Haven | Areas established by private interests, usually sport fishermen, to simulate natural reefs and wrecks that attract fish. The reefs are constructed by dumping assorted junk in areas which may be of very small extent or may stretch a considerable distance along a depth contour. Fish havens are outlined and labeled on charts. Also called fishery reefs. [14] |
| 729 | Fixed Star | A star. The expression is used particularly to distinguish stars from other heavenly bodies; so called by ancients to distinguish stars from the wandering planets. [14] |
| 730 | Ionosphere | That part of the atmosphere, extending from about 70 to 500 km, in which ions and free electrons exist in sufficient quantities to reflect electromagnetic waves. [14] |
| 731 | Jet Stream | Relatively strong winds concentrated within a narrow band in the atmosphere. [1] |
| 732 | Local Time | See time. [14] |
| 733 | Neap Range | The mean semidiurnal range of tide when neap tides are occurring; the mean difference in height between neap high water and neap low water. Sometimes called mean neap range. [14] |
| 734 | Neap Tides | Tides of decreased range or tidal currents of decreased speed occurring semimonthly as the result of the Moon being in quadrature. The neap range (Np) of the tide is the average range occurring at the time of neap tides and is most conveniently computed from the harmonic constants. It is smaller than the mean range where the type of tide is either semi diurnal or mixed and is of no practical significance where the type of tide is predominantly diurnal. The average height of the high waters of the neap tide is called neap high water or high water neaps (MHWN) and the average height of the corresponding low waters is called neap low water or low water neaps (MLWN). [22] |
| 735 | Opposition | The situation of two periodic quantities differing by half a cycle. In astronomy, the situation of two celestial bodies having either celestial longitudes or sidereal hour angles differing by 180°. The term is usually used only in relation to the position of a superior planet or the moon with reference to the sun. [14] |
| 736 | Polar Axis | See axis. [14] |
| 737 | Resolution | The separation by an optical system of parts of an object or of two or more objects close together. The degree of ability to make such a separation, called resolving power, is expressed as the minimum distance between two objects that can be separated. The degree of ability of a radar set to indicate separately the echoes of two targets in range and bearing. [14] |
| 738 | Saturation | The condition existing when the greatest possible amount of anything has been reached, as a magnetic substance which cannot be further magnetized, or an electronic aid to navigation which is being used by all the craft it can handle. At given temperature and pressure, state of moist air whose mixing ratio is such that the moist air can co-exist in neutral equilibrium with an associated condensed phase (liquid or solid) at the same temperature and pressure, the surface of separation being plane. [14] |
| 739 | Small Halo | See halo. [14] |
| 740 | Wire Angle | The angle measured between the sounding wire, or the oceanographic wire, and the vertical. [14] |
| 741 | Conspicuous | Adj.). Term applied to an object either natural or artificial which is distinctly and notably visible from seaward. [14] |
| 742 | Core Barrel | The tubular section of a core sampling device. Bottom sediment samples are collected either directly in the core barrel or in a plastic liner placed inside it. Also called coring (or core) tube. [14] |
| 743 | Culmination | The position of a heavenly body when at highest apparent altitude. Also, for a heavenly body which is continually above the horizon, the position of lowest apparent altitude. Culmination occurs when the body transits the local meridian. See meridian transit. [14] |
| 744 | Drift Angle | The difference between course steered and course made good when due to action of current and wind. The angle between the tangent to the turning circle and the centerline of the ship. [14] |
| 745 | Fathom Line | A depth curve with depth expressed in fathoms. Also called fathom curve, isobath. [14] |
| 746 | Hydrography | Hydrography is the branch of applied sciences which deals with the measurement and description of the physical features of oceans, seas, coastal areas, lakes and rivers, as well as with the prediction of their change over time, for the primary purpose of safety of navigation and in support of all other marine activities, including economic development, security and defence, scientific research, and environmental protection. [14] |
| 747 | Lens System | The combination of two or more lenses placed in series on the same principal axis. [14] |
| 748 | Lunar Month | See month: synodical. [14] |
| 749 | Maintenance | All procedures and activities required to keep equipment operational. [14] |
| 750 | Meteorology | Science of the atmosphere. [14] |
| 751 | Nadir Point | See nadir: photograph. [14] |
| 752 | Retardation | In electronic navigation, the amount of delay in time or phase angle introduced by the resistivity of the ground over which the signal is passing. In tide terminology, daily retardation. [14] |
| 753 | Thermograph | Thermometer used to give a graphical record of the time variations of temperature. [14] |
| 754 | Tide Tables | Tables listing daily predictions, usually a year in advance, of the times and heights of the tide. These predictions are usually supplemented by tidal differences and tidal constants by means of which additional predictions can be obtained for numerous other places. See tide prediction. [14] |
| 755 | Troposphere | Lower part of the terrestrial atmosphere, extending from the surface up to a height varying from about 9 km at the poles to about 17 km at the equator, in which temperature decreases fairly regularly with height. From an analogy with the atmosphere, the term is sometimes applied in oceanography to the upper ocean layer of relatively high temperature that is found in middle and lower latitudes and within which strong currents are present. See stratosphere. [14] |
| 756 | Ultraviolet | (Adj.). Having a frequency immediately beyond the violet end of the visible spectrum. Said of rays of shorter wavelength than visible light but longer than x-rays. [14] |
| 757 | Environmental Lapse Rate | The rate of decrease of air temperature with elevation. It is most often measured with a radiosonde. [1] |
| 758 | Gap | A narrow break in a ridge or rise. [14] |
| 759 | Key | See cay. [14] |
| 760 | MSL | Mean Sea Level (MSL) ; The arithmetic mean of hourly heights observed. Shorter series are specified in the name; e.g. monthly mean sea level and yearly mean sea level. [21] |
| 761 | Sac | An indentation in the contours on a chart showing submarine relief which is analogous to a gulf on the surface. The opposite term is submarine peninsula. [14] |
| 762 | Dyne | The unit of force in the cgs system. [14] |
| 763 | Gulf | A part of the sea extending into the land, usually larger than a bay. [14] |
| 764 | Menu | A list of commands and/or options. The user selects the desired command by moving the cursor to the respective position on the menu or by entering an appropriate code at the command entry line of the display. [14] |
| 765 | MHWN | Mean High Water Neaps (MHWN) ; The height of mean high water neaps is the average throughout the year (when the average maximum declination of the moon is 23.5°) of two successive high waters during those periods of 24 hours when the range of the tide is at its least. The values of MHWN vary from year to year with a cycle of approximately 18.6 years. [24] |
| 766 | MHWS | Mean High Water Springs (MHWS) ; The height of mean high water springs is the average throughout the year (when the average maximum declination of the moon is 23.5°) of two successive high waters during those periods of 24 hours when the range of the tide is at its greatest. The values of MHWS vary from year to year with a cycle of approximately 18.6 years. [24] |
| 767 | MLWN | Mean Low Water Neaps (MLWN) ; The height of the mean low water neaps is the average height obtained by the two successive low waters during periods of 24 hours when the range of the tide is at its least. The values of MLWN vary from year to year with a cycle of approximately 18.6 years. [24] |
| 768 | MLWS | Mean Low Water Springs (MLWS) ; The height of mean low water springs is the average throughout the year (when the average maximum declination of the moon is 23.5°) of two successive high waters during those periods of 24 hours when the range of the tide is at its greatest. The values of MLWS vary from year to year with a cycle of approximately 18.6 years. [24] |
| 769 | Quay | A wharf approximately parallel to the shoreline and accommodating ships on one side only, the other side being attached to the shore. It is usually of solid construction, as contrasted with the open pile construction usually used for piers. [14] |
| 770 | Tank | A fixed structure for storing liquids. [14] |
| 771 | Tuff | A rock formed of fragments of volcanic origin, dust, ashes, etc., thrown out of a volcano during an eruption, frequently hardened to a rock. Hence tuff-cone, a volcanic cone built up of such material. [14] |
| 772 | Yard | A unit of length equal to 3 feet, 36 inches, or 0.9144 metre. [14] |
| 773 | Abeam | In a line approximately at right angles to the ship's keel; also: the waist or middle part of the ship. [14] |
| 774 | Agger | See tide: double. [14] |
| 775 | Delta | An area of alluvial deposit, usually triangular in outline, near the mouth of a river. [14] |
| 776 | Inlet | A narrow opening by which the water penetrates into the land. [14] |
| 777 | Islet | A small island. [14] |
| 778 | Jetty | In US Terminology, a structure, such as a wharf or pier, so located as to influence current or protect the entrance to a harbor or river. In British terminology, a pier, usually of solid construction, intended as a berthing place for vessels. See dock, landing, wharf. [14] |
| 779 | Laser | Light amplification by stimulated emission of radiation. A device that produces an intense beam of monochromatic, spatially coherent light. [14] |
| 780 | Levee | A depositional natural embankment bordering a canyon, valley or sea channel on the ocean floor. [14] |
| 781 | Lidar | (light detection and ranging) an instrument that measures distance to a reflecting object by emitting timed pulses of laser light and measuring the time between emission and reception of reflected pulses. The measured time interval is converted to distance. In survey use, the lidar system usually scans the light pulses across the track of the survey platform (usually an aircraft) so that successive pulses cover a swath(e) either side of the platform's track. Infra-red lasers will reflect off land and water and are normally used for topographic lidar surveys. Blue-green lasers will penetrate water and are used in hydrographic lidar surveys. [14] |
| 782 | Probe | Any device inserted in an environment for the purpose of obtaining information about the environ-ment. [14] |
| 783 | Siren | A type of fog signal apparatus which produces sound by virtue of the passage of air through slots or holes in a revolving disk. [14] |
| 784 | Spoil | Mud, sand, silt or other deposit obtained from the bottom of a channel or harbor by dredging. [14] |
| 785 | Swash | A narrow channel or sound within a sand bank, or between a sand bank and the shore. Also called swash way. A bar over which the sea washes. The rush of water up onto a beach following the brea-king of a wave. [14] |
| 786 | Trend | The general direction of something, such as a coastline. [14] |
| 787 | Canyon | A relatively narrow, deep depression with steep sides, the bottom of which generally has a continuous slope. [14] |
| 788 | Careen | Causing a vessel to lie over on one side. [14] |
| 789 | Drogue | A current measuring assembly consisting of a weighted parachute and an attached surface buoy. Also called parachute drogue. [14] |
| 790 | Isogon | Line which is the locus of points at which the direction of wind is the same. [14] |
| 791 | Isopor | See isoporic line. [14] |
| 792 | Legend | A description, explanation, table of symbols, and other information, printed on a map or chart to provide a better understanding and interpretation of it. The title of a map or chart formerly was considered part of the legend, but this usage is obsolete. [14] |
| 793 | Matrix | In oceanography, rock or sediment in which larger grains are embedded in a mass of smaller grains. In printing, a metal plate, usually of copper, for moulding the face of a type. In graphic arts, a mold in which type characters are cast in line-casting machines and foundry type. [14] |
| 794 | Medusa | See coelenterate and jellyfish. [14] |
| 795 | Nebula | (pl. Nebulae). An aggregation of matter outside the solar system, large enough to occupy a perceptible area but which has not been resolved into individual stars. [14] |
| 796 | Occupy | (v.t.). In surveying, to observe with a surveying instrument at a station; also, to set a surveying instrument over a point for the purpose of making observations. In oceanography, to stop a ship at a selected location, an oceanographic station, for the purpose of gathering oceanographic observations. [14] |
| 797 | Offset | In surveying, a short line perpendicular to a surveyed line, measured to a line or point for which data are desired, thus locating the second line or point with reference to the first or surveyed line. An offset is also a jog in a survey or other line, the line having approximately the same direction both before and after passing the jog. Offsets are measured from a surveyed line or lines to the edges of an irregular-shaped body of water, or to any irregular line which it is desired to locate. [14] |
| 798 | P-Code | The precise (or protected) gps code; a very long (about 1014 bit) sequence of pseudo-random binary biphase modulations on the gps carrier at a chip rate of 10.23 MHz which does not repeat itself for about 267 days. Each one-week segment of the p-code is unique to one gps satellite and is reset each week. See also c/a code. [14] |
| 799 | Ramark | A radar marker beacon which continuously transmits a signal appearing as a radial line on the ppi, the line indicating the direction of the beacon. Ramarks are intended primarily for marine use. The name 'ramark' is derived from the words radar marker. [14] |
| 800 | Regime | In climatology, term used to characterize the seasonal distribution of one or more elements at a given place. [14] |
| 801 | Ruling | A mechanically produced series of equally spaced parallel lines at a predetermined 'angle of ruling'. Used to distinguish particular areas of a map by providing a paler shade of the full printing colour. [14] |
| 802 | Run-Up | The rush of water up a structure on the breaking of a wave. The amount of run-up is the vertical height above still water level that the rush of water reaches. See uprush. [14] |
| 803 | Seaway | A moderately rough sea. Used chiefly in the expression 'in a seaway'. Headway of a vessel. The sea as a route of travel from one place to another; a shipping lane. [14] |
| 804 | Sinker | Weight used to sink fishing line or sounding line. [14] |
| 805 | Strand | The portion of the seashore between high and low water line. [14] |
| 806 | Taping | The operation of measuring a distance on the ground using a tape or ribbon of metal or other material. Also called chaining. [14] |
| 807 | Tracer | Foreign substance introduced into the water by natural or artificial means which enables determination of water movement through measurement of distribution and location of the substance at the same time. [14] |
| 808 | Y-Axis | A vertical axis in a system of rectangular coordinates; that line on which distances above or below (north or south of) a reference line are marked, especially on a map, chart, or graph. The line which is perpendicular to the x-axis and passes through the origin. [14] |
| 809 | Bay Ice | Level fast ice of more than one winter's growth, which may be nourished by surface layers of snow. Thickness of ice and snow up to about 2 m above sea level. When bay ice becomes thicker than this, it is called an ice shelf. [14] |
| 810 | Bedrock | Any solid rock underlying soil or unconsolidated sediments. [14] |
| 811 | Calorie | A unit of quantity of heat, originally defined as the amount of heat required to raise the temperature of one gram of water through one degree c. The 15-degree gram-calorie is the amount of heat required to raise the temperature of one gram of water from 14°.5 c to 15°.5 c and is equal to 4.1855 joules. [14] |
| 812 | Candela | The unit of luminous intensity in the si system. [14] |
| 813 | Daymark | 1. The identifying characteristics of an aid to navigation which serve to facilitate its recognition against a daylight viewing background. On those structures that do not by themselves present an adequate viewing area to be seen at the required distance, the aid is made more visible by affixing a daymark to the structure. A daymark so affixed has a distinctive colour and shape depending upon the purpose of the aid. 2. An unlighted navigational mark. [14] |
| 814 | Dolphin | A post or group of posts, used for mooring or warping a vessel, or as an aid to navigation. The dolphin may be in the water, on a wharf or on the beach. [14] |
| 815 | El Niño | An extensive ocean warming that begins along the coast of peru and ecuador and extends westward over the tropical pacific. Major el niño events, or strong el niños, occur once every 2 to 7 years as a current of nutrient-poor tropical water moves southward along the west coast of south america. [1] |
| 816 | Gimbals | A device consisting of two rings pivoted at right angles to each other, for supporting anything, such as an instrument, in such a manner that it will remain essentially horizontal when the support tilts. Also called cardanic suspension. [14] |
| 817 | Glonass | A space-based, radio-positioning, navigation and time-transfer system operated by the government of the russian federation. Glonass to which differential corrections have been applied is known as differential glonass (dglonass). See also global navigation satellite system. [14] |
| 818 | Impulse | See pulse. [14] |
| 819 | Isobath | See depth curve, fathom line. [14] |
| 820 | Rafting | Pressure process whereby one piece of ice overrides another. Most common in new and young ice. [14] |
| 821 | Seaweed | Any macroscopic marine alga or seagrass. [14] |
| 822 | Sunspot | Any of the dark spots sometimes seen at the surface of the sun; they are believed to have some connection with magnetic disturbances on earth. [14] |
| 823 | Terrace | A relatively flat horizontal or gently inclined surface, sometimes long and narrow, which is bounded by a steeper ascending slope on one side and by a steeper descending slope on the opposite side. [14] |
| 824 | Tropics | See torrid zone. [14] |
| 825 | Abscissa | See coordinates: plane rectangular. [14] |
| 826 | Achromat | See achromatic lens. [14] |
| 827 | Acid Fog | Cloud droplets or raindrops combining with gaseous pollutants, such as oxides of sulfur and nitrogen, to make falling rain (or snow) acidic pH less than 5.0. If fog droplets combine with such pollutants, it becomes acid fog. [1] |
| 828 | Anaglyph | A stereogram in which the two views are printed or projected superimposed in complementary colors, usually red and green. By viewing through filter spectacles of corresponding complementary colors a stereoscopic image is formed. [14] |
| 829 | Analogue | The way of representing information by continuous data. [14] |
| 830 | Aphelion | That orbital point farthest from the sun when the sun is the center of attraction, as opposed to perihelion. [14] |
| 831 | Backrush | The seaward return of water following uprush of waves on a beach. [14] |
| 832 | Binnacle | The stand in which a compass is mounted and in which lighting and compensatory units are carried. [14] |
| 833 | Bulkhead | On land, a structure or partition built to retain or prevent sliding of the land. A secondary purpose is to protect the upland against damage from wave action. Bulkheads are frequently backfilled thereby increasing the utility of the adjacent land area. [14] |
| 834 | Catenary | The curve formed by a uniform cable, chain, or tape supported only at its ends. [14] |
| 835 | Chartlet | A small auxiliary chart giving new details on a particular area, to be added to the chart after publication. Also, called block correction or chart amendment patch. A small chart, such as one showing the coverage area of electronic navigational systems, with the distribution of its lines of position, corrections to be applied to readings, location and identification of transmitters, etc. [14] |
| 836 | Detritus | In geology, material removed by disintegration and other processes from the surface of rocks. There is a general tendence to use debris. In marine biology, suspended matter of organic origin permanently incapable of reproduction organic detritus may often 'collect' a considerable amount of inorganic material. [14] |
| 837 | Downwind | (Adj. And adv.). In the direction toward which the wind is blowing. The opposite is upwind. [14] |
| 838 | Drafting | The art of drawing from given specifications. [14] |
| 839 | Gridiron | See careening grid. [14] |
| 840 | Hardware | All physical material components of a computer system as e.g. Central processing unit (cpu), peripheral devices etc. May also include individual chips. [14] |
| 841 | Ice Cake | A floe smaller than 10 m across. If less than 2 m, it is termed brash ice or small ice cake. [14] |
| 842 | Ice Rise | A mass of ice resting on rock and surrounded either by an ice shelf or partly by an ice shelf and partly by sea. No rock is exposed and there may be none above sea level. Ice rises often have a dome-shaped surface. The largest known is about 100 km across. [14] |
| 843 | Ice Wall | An ice cliff forming the seaward margin of an inland ice sheet, ice piedmont or ice rise. The rock basement may be at or below sea level. See ice front. [14] |
| 844 | Landmark | Any fixed object used to mark a boundary on the ground. - 2. Any prominent object at a fixed location on land which can be used in determining a location or a direction. [14] |
| 845 | Leadsman | A person using a sounding lead to determine depth of water. [14] |
| 846 | Mangrove | One of several genera of tropical trees or shrubs which produce many prop roots and grow along low-lying coasts into shallow water. [14] |
| 847 | Mean Sun | See sun. [14] |
| 848 | Midnight | Twelve hours from noon, or the instant the time reference crosses the lower branch of the refe-rence celestial meridian. [14] |
| 849 | Plankton | The passively drifting or weakly swimming organisms in marine and fresh waters. [14] |
| 850 | Scanning | Directing a beam of radiant energy successively over all points of a given region. [14] |
| 851 | Seaboard | A general term for the rather extensive coastal region bordering the sea. [14] |
| 852 | Sky Wave | See wave. [14] |
| 853 | Surveyor | A person engaged in surveying. [14] |
| 854 | Taffrail | The after rail at the stern of a vessel. [14] |
| 855 | Upstream | (Adj. & adv.). Toward the source of a stream. The opposite is downstream. [14] |
| 856 | Waterway | A line of water (river, channel, etc.) Which can be utilized for communication or transport. [14] |
| 857 | Wreckage | Goods or parts of a wrecked vessel washed ashore or afloat; remains of a wreck. [14] |
| 858 | Anthelion | Pure white, rounded spot, but sometimes iridescent or surrounded by coloured rings or arcs, which appears on very rare occasions opposite the sun and at the same height above the horizon. [14] |
| 859 | Backsight | In nautical astronomy, an observation of a celestial body made by facing 180° from the azimuth of the body. In levelling, a reading on a levelling rod held on a point whose elevation has been previously determined and which is not the closing sight of a level circuit. Also written as two words. See also foresight. [14] |
| 860 | Civil Day | See day. [14] |
| 861 | Data Base | An organized collection of data stored so as to be capable of use by relevant applications with the data being accessed by different logical paths. It should be application independent. [14] |
| 862 | Engraving | The act, process or art of cutting or etching designs or letters on metal plates, wooden blocks, etc. For printing. Any printed impression made from an engraved surface. [14] |
| 863 | Footscrew | See levelling screw. [14] |
| 864 | Free Wave | See wave. [14] |
| 865 | Index Arm | A slender bar carrying an index; particularly that bar which pivots at the center of curvature of the arc of a marine sextant and carries the index and the vernier or micrometer. Also called index bar. [14] |
| 866 | Isoclinal | N.). See isoclinal line. [14] |
| 867 | Isopycnic | (Adj.). Of or pertaining to equal density. [14] |
| 868 | Isopycnic | (n.). See isopycnic line. [14] |
| 869 | Landspout | Relatively weak non supercell tornado that originates with a cumuliform cloud in its growth stage and with a cloud that does not contain a mid-level mesocyclone. Its spin originates near the surface. Landspouts often look like waterspouts over land. [1] |
| 870 | Level Ice | Sea ice with a flat surface which has never been hummocked. [14] |
| 871 | Limestone | A rock which consists chiefly of calcium carbonate. [14] |
| 872 | Neap Rise | See mean neap rise. [14] |
| 873 | Oil Field | An area in which oil occurs in quantities worthy of exploitation. [14] |
| 874 | Planetary | (Adj.). Of a planet or the planets. Like a planet. Terrestrial. [14] |
| 875 | Polar Ice | Sea ice that is more than one year old (in contrast to winter ice). The WMO code defines polar ice as any sea ice more than one year old and more than 3 meters thick. [14] |
| 876 | Pollution | The direct or indirect alteration of the physical, chemical, thermal, biological or radioactive properties of any part of the environment in such a way as to create a hazard or potential hazard to the health, safety or welfare of any living species. [14] |
| 877 | Reservoir | A place where anything is collected and stored, generally in large quantity; especially a pond, lake or basin, either natural or artificial, for the storage, regulation and control of water. [14] |
| 878 | Responsor | A radio receiver which receives a reply from a transponder and produces an output suitable for feeding to a display system. A responsor is usually combined in a single unit with an interrogator which sends out the pulse that triggers a transponder, the combined unit being called an inter-rogator-responsor. [14] |
| 879 | Surf Zone | The area between the outermost breaker and the limit of wave uprush. [14] |
| 880 | Tide Wave | A long-period wave associated with the tide-producing forces of the moon and sun; identified with the rising and falling of the tide. Also called tide bulge. See tide, tidal movement, stand of tide. [14] |
| 881 | Titration | A chemical method for determining the concentration of a substance in solution. In oceanography, the most common titration is that for chlorinity. [14] |
| 882 | Upwelling | The process by which water rises from a lower to a higher depth, usually as a result of divergence and offshore currents. See sinking. [14] |
| 883 | Wind Wave | See wave. [14] |
| 884 | Young Ice | Newly formed level ice in the transition stage of development from ice rind or pancake ice to winter ice. Thickness from 5 to 15 cm. [14] |
| 885 | Anemograph | An instrument which records wind speed and direction. See also anemometer. [14] |
| 886 | Bathymetry | The determination of ocean depths. The general configuration of sea floor as determined by profile analysis of depth data. [14] |
| 887 | Chlorinity | The total amount in grams of chlorine, bromine and iodine contained in one kilogram of sea water, assuming that the bromine and the iodine had been replaced by chlorine. See salinity. [14] |
| 888 | Day: Solar | The duration of one rotation of the earth on its axis, with respect to the sun. This may be either a mean solar day, or an apparent solar day, as the reference is the mean or apparent sun, respectively. The duration of one apparent rotation of the sun. [14] |
| 889 | Divergence | In oceanography, a horizontal flow of water, in different directions, from a common center or zone; often associated with upwelling. [14] |
| 890 | Driver Rod | A device employed together with a sinker to obtain bottom samples when wire sounding. It consists, essentially, of a galvanized iron tube the lower part of which contains a flap valve for retaining a bottom specimen. The tube releases the sinker when it strikes the bottom. Also called driver tube. [14] |
| 891 | Field Stop | The physical element (such as an aperture stop, diaphragm or lens periphery) of an optical system which limits the field of view covered by the system. [14] |
| 892 | Gust Front | A boundary that separates a cold downdraft of a thunderstorm from warm, humid surface air. On the surface its passage resembles that of a cold front. [1] |
| 893 | Gyro: Free | A two-degree-of-freedom gyro or a gyro the spin axis of which may be oriented in any specified attitude. Also called free gyroscope. [14] |
| 894 | Ice Island | A form of tabular berg found in the arctic ocean, with a thickness of 30 to 50 m and from a few thousand square meters to 500 sq. Km in area. Ice islands are characterized by a regularly undulating surface, which gives them a ribbed appearance from the air. [14] |
| 895 | Index Mark | In photogrammetry, a real mark (such as a cross or dot) lying in the plane or the object space of a photograph and used singly as a reference mark in certain types of monocular instruments, or as one of a pair to form a floating mark (as in certain types of stereoscopes). [14] |
| 896 | Inmarsat-C | The digital satellite communications system for store-and-forward text or data messaging using mobile terminals with omni-directional antennas. Inmarsat-c is the only system (2011) that allows ships to meet the majority of the satellite communication requirements of the gmdss including distress alerting, reception of maritime safety information and general communications. [14] |
| 897 | Light List | See list of lights. [14] |
| 898 | Lighthouse | A distinctive structure on or off a coast exhibiting a major light designed to serve as an aid to navigation. [14] |
| 899 | On The Bow | Bearing approximately 045° relative (on the starboard bow) or 315° relative (on the port bow). The expression is often used loosely for broad on the bow, or bearing exactly 045° or 315° relative. See also broad on the bow. [14] |
| 900 | Perihelion | That orbital point nearest the sun, when the sun is the center of attraction, as opposed to aphelion. [14] |
| 901 | Rain Gauge | see gauge. [14] |
| 902 | Rock Awash | A rock awash at chart datum. [14] |
| 903 | Roundabout | A routing measure comprising a separation point or circular separation zone and a circular traffic lane within defined limits. Traffic within the roundabout is separated by moving in a counter-clockwise direction around the separation point or zone. [14] |
| 904 | Sea Breeze | A coastal local wind that blows from the ocean onto the land. The leading edge of the breeze is termed a sea-breeze front. [1] |
| 905 | Streamline | A line of flow. In meteorology, line envelope in space of the tangents to the instantaneous wind directions at a given time. Also written as two words. See also trajectory. [14] |
| 906 | Tidal Wave | See wave. [14] |
| 907 | Tide Cycle | See tidal cycle. [14] |
| 908 | Tide Range | See range of tide. [14] |
| 909 | Tide Staff | A tide gauge consisting of a vertical graduated pole from which the height of tide at any time can be read directly. Also called tide pole. [14] |
| 910 | Time: Mean | See time: mean solar. [14] |
| 911 | Tropopause | Upper limit of the troposphere. [14] |
| 912 | Ultrasonic | (Adj.). Having a frequency above the audible range. [14] |
| 913 | Undulating | (Adj.). Having the form of waves or swells, as undulating land. [14] |
| 914 | Undulation | A continuously propagated motion to and from, in any fluid or elastic medium, with no permanent translation of the particles themselves. [14] |
| 915 | Wave Train | A series of waves moving in the same direction. See wave: solitary. [14] |
| 916 | Wind Force | Number on a progressive scale (beaufort wind scale) corresponding to the effects produced by winds within a range of speeds. Force exerted by the wind on a construction, object, etc. [14] |
| 917 | Wind Shear | The rate of change of wind speed or wind direction over a given distance. [1] |
| 918 | Y-Parallax | See parallax. [14] |
| 919 | Archipelago | A group of islands. [14] |
| 920 | Circumpolar | (Adj.). Revolving about the elevated pole without setting. A celestial body is circumpolar when its polar distance is approximately equal to or less than the latitude of the observer. The actual limit is extended somewhat by the combined effect of refraction, semidiameter, parallax, and the height of the observer's eye above the horizon. [14] |
| 921 | Coastlining | The process of obtaining data from which the coastline can be drawn on a chart. [14] |
| 922 | Course Line | A line of position approximately parallel to the course. [14] |
| 923 | Danger Area | An area designated by a proper authority, in which a danger to craft exists. Also called danger zone. [14] |
| 924 | Datum Level | See datum: vertical control and datum: chart. [14] |
| 925 | Dumpy Level | See levelling instrument: dumpy level. [14] |
| 926 | Ebb Current | See ebb stream. [14] |
| 927 | Equinoctial | See equator: celestial. [14] |
| 928 | Gauge: Tide | A device for measuring the height of tide. A graduated staff in a sheltered area where visual observations can be made; or it may consist of an elaborate recording instrument making a continuous graphic record of tide height against time. Such an instrument is usually actuated by a float in a pipe communicating with the sea through a small hole which filters out shorter waves. [14] |
| 929 | Ground Wave | See wave. [14] |
| 930 | Index Error | See error. [14] |
| 931 | Lithography | The art or process of printing from a flat stone or metal plate by a method based on the repulsion between grease and water. The original lithographic material was bavarian limestone; but zinc and aluminium are now used. [14] |
| 932 | Median Line | A line every point of which is equidistant from the nearest points on the baselines of two or more states between which it lies. [14] |
| 933 | Mesocyclone | A vertical column of cyclonically rotating air within a supercell thunderstorm. [1] |
| 934 | On The Beam | Bearing approximately 090° relative (on the starboard beam) or 270° relative (on the port beam). The expression is often used loosely for broad on the beam, or bearing exactly 090° or 270° relative. Also called abeam. See also broad on the beam. [14] |
| 935 | Outer Limit | The extent to which a coastal state claims or may claim a specific jurisdiction in accordance with the provisions of international law. [14] |
| 936 | Phase Angle | The phase difference of two periodically recurring phenomena of the same frequency, expressed in angular measure. The angle at a celestial body between the sun and earth. [14] |
| 937 | Polar Front | Quasi-permanent front of great extent, of middle latitudes, which separates relatively cold polar air and relatively warm tropical air, and on which waves are produced. [14] |
| 938 | Rising Tide | See tide. [14] |
| 939 | Sedimentary | (Adj.). Formed by the deposition of sediment. [14] |
| 940 | Signal Lamp | See lamp. [14] |
| 941 | Slant Range | See slant distance. [14] |
| 942 | Spring Rise | See mean spring rise. [14] |
| 943 | Stereoscope | A binocular optical instrument for helping an observer to view photographs, or diagrams, to obtain the mental impression of a three-dimensional model. [14] |
| 944 | Stereoscopy | The science and art which deals with the use of binocular vision for observation of a pair of overlapping photographs or other perspective views, and with the methods by which such viewing is produced. [14] |
| 945 | Tidal Range | See range of tide. [14] |
| 946 | Projection: Transverse Mercator | A projection of the cylindrical type, being in principle equivalent to the regular Mercator projection turned (transverse) 90° in azimuth. In this projection, the central meridian is represented by a straight line, corresponding to the line which represents the equator on the regular Mercator projection. Neither the geographical meridians, except the central meridian, nor the geodetic paral-lels, except the equator (if shown), are represented by straight lines. It is a conformal projection. Also called transverse cylindrical orthomorphic projection. [14] |
| 947 | Bog | Wet spongy ground consisting of decaying vegetation, which retains stagnant water, too soft to bear the weight of any heavy body. [14] |
| 948 | MWL | Mean water level (MWL) ; The average of all hourly water levels over the available period of record. [12] |
| 949 | Beat | The periodic variation that results from the superposition of two oscillations whose frequencies differ by a small amount. [14] |
| 950 | Coma | An aberration affecting the sharpness of images off the axis, in which rays from a point object off the axis passing through a given circular zone of the lens, come to a focus in a circle rather than a point, and the circles formed by rays through different zones are of different sizes and are located at different distances from the axis. Therefore, the image of a point object is comet-shaped. The foggy envelope surrounding the nucleus of a comet. [14] |
| 951 | Crab | The condition caused by failure to orient a camera with respect to the track of the airplane. In vertical photography, crab is indicated by the edges of the photographs not being parallel to the airbase lines. [14] |
| 952 | Dgps | See differential gps [14] |
| 953 | Dune | A mound, ridge or hill of drifted sand on the seacoast or in a desert. See sand dune and down. [14] |
| 954 | Gale | Wind with a speed between 32 and 37 knots (beaufort scale wind force 8). [14] |
| 955 | Gnss | See global navigation satellite system [14] |
| 956 | Grab | A kind of closing scoop or bucket used in dredging or for bringing up bottom samples. [14] |
| 957 | HHWL | Highest High Water Level (HHWL) [-] |
| 958 | Hook | A sharp bend or angle in the course or length of anything; especially a bend in a river. A projecting corner, point or spit of land. [14] |
| 959 | LLWL | Lower Low Water Line (LLWL) ; The intersection of the land (shore) with the water surface at the elevation of mean lower low water. [23] |
| 960 | Loch | The Scottish term for (1) a lake, and (2) a fiord. [14] |
| 961 | Marl | A crumbling, earthy deposit, particularly one of clay mixed with sand, lime, decomposed shells, etc. Sometimes a layer of marl becomes quite compact. Part of the ocean bed is composed of marl. [14] |
| 962 | Mesa | A high tableland (s.w. And w. United states). [14] |
| 963 | MHWL | Mean High Water Line (MHWL); The line on a chart or map which represents the intersection of the land with the water surface at the elevation of mean high water. [22] |
| 964 | Mire | A piece of wet swampy ground. [14] |
| 965 | MLWL | Mean Low Water Line (MLWL); The intersection of the land (shore) with the water surface at the elevation of water level. [23] |
| 966 | Neck | In oceanography, the narrow band of water flowing swiftly seaward through the surf. See current: rip. In geography, a narrow piece of land with water on each side; an isthmus. [14] |
| 967 | Ramp | A sloping structure that can either be used, as a landing place, at variable water levels, for small vessels, landing ships, or a ferry boat, or for hauling a cradle carrying a vessel. An accumulation of snow that forms an inclined plane between land or land ice elements and sea ice or ice shelf. Also called drift ice foot. [14] |
| 968 | Sbes | See single beam echo sounder [14] |
| 969 | Spur | A subordinate elevation, ridge or rise projecting outward from a larger feature. [14] |
| 970 | Vein | A narrow lead or lane in pack ice. In mineralogy, a crack or fissure in the rocks of the earth's crust in which highly heated waters from below have deposited from solution crystalline minerals (especially vein quartz) and, under certain circumstances, metallic minerals of economic importance. [14] |
| 971 | Volt | The unit of potential difference or electromotive force in the si system. [14] |
| 972 | Weir | A dam erected across a river to raise the level of the water. A fence of stakes set in a river or along the shore as a trap for fish. The word is now restricted to smaller works, the larger are called dams. [14] |
| 973 | Zoom | A method of enlarging graphics on a graphical display, usually a function provided by the hardware of the screen. Either a selected window may be enlarged to cover the entire screen or by repeatedly pressing a key, a stepwise or continuous enlargement of the screen contents can be invoked, keeping the graphics centered at the screen's center. [14] |
| 974 | Atlas | A collection of charts or maps to be kept (loose or bound) in a volume. [14] |
| 975 | Atoll | A coral island consisting of a ring-shaped reef nearly or entirely surrounding a central lagoon. [14] |
| 976 | Bayou | A minor sluggish waterway or estuarial creek, generally tidal or characterized by a slow current, with a course generally through lowlands or swamps, tributary to or connecting with other bodies of water. Various specific meanings have been implied in different parts of the southern united states. Sometimes called slough. [14] |
| 977 | Bench | See terrace. [14] |
| 978 | Clean | (Adj.). Free from obstructions, unevenness, imperfections, as a clean anchorage. [14] |
| 979 | Fucus | See rockweed. [14] |
| 980 | Gorge | A narrow opening, between hills, usually with precipitous sides. [14] |
| 981 | Guyot | See table mount. [14] |
| 982 | Halos | Rings or arcs that encircle the sun or moon when seen through an ice crystal cloud or a sky filled with falling ice crystals. Halos are produced by refraction of light. [1] |
| 983 | Joule | The unit of work or energy in the si system. [14] |
| 984 | Lagan | See jettison. [14] |
| 985 | Panel | In cartography, the completed assembly of pieces of film positives onto a grid or projection which is used as a base for compilation. In photogrammetry, an element of a target used for control station identification on aerial photography. [14] |
| 986 | Perch | A staff placed on top of a buoy, rock, or shoal as a mark for navigators. A ball or cage is sometimes placed at the top of the perch, as an identifying mark. A unit of length equal to 5.5 yards or 16.5 feet. Also called rod, pole. [14] |
| 987 | Pingo | Small conical hills having a large central core of ice formed from the encroachment of permafrost and the resulting hydrostatic pressure. [14] |
| 988 | Saros | The eclipse cycle of about 18 years, almost the same length as 223 synodical months. At the end of each saros the sun, moon, and line of nodes return to approximately the same relative positions, and another series of eclipses begins, closely resembling the series just completed. [14] |
| 989 | Scour | The action of a current or flow of water in clearing away mud or other deposit; in civil engineering an artificial current or flow produced for this purpose. [14] |
| 990 | Shoot | (v.t.). To observe the altitude of (a celestial body). [14] |
| 991 | Spray | Ensemble of water droplets torn by the wind from the surface of an extensive body of water, gene-rally from the crests of waves, and carried up a short distance into the air. [14] |
| 992 | Tyfon | See typhon. [14] |
| 993 | Vigia | A pinnacle, rock, or shoal the existence or position of which is doubtful, or a warning note to this effect on a chart. [14] |
| 994 | Wrack | See rockweed. [14] |
| 995 | Albedo | The ratio of radiant energy reflected to that received by a surface, usually expressed as a percentage. [14] |
| 996 | Ampere | The unit of density of electric current in the si system. [14] |
| 997 | Boomer | Seismic instrument for shallow penetration work. The boomer transducer produces acoustic pulses by the motion of a metal plate in the water. [14] |
| 998 | Cirrus | A high cloud composed of ice crystals in the form of thin, white, featherlike clouds in patches, filaments, or narrow bands. [1] |
| 999 | Defile | A narrow pass or gorge between mountains. [14] |
| 1000 | F-Stop | See aperture: relative. [14] |
| 1001 | Furrow | On the sea floor, a closed, linear, narrow, shallow depression. [14] |
| 1002 | Gravel | Loose detrital material ranging in size from 2 to 256 mm. [14] |
| 1003 | Intake | The place where water is taken into a channel or pipe from a river or other body of water, to drive a mill, or supply a canal, waterworks, etc. [14] |
| 1004 | Jetsam | See jettison. [14] |
| 1005 | Leaper | See lipper. [14] |
| 1006 | Mantle | The relatively plastic region between the crust and core of the earth. Also called asthenosphere. [14] |
| 1007 | Micron | One millionth of a metre; one thousandth of a millimeter. [14] |
| 1008 | Navtex | The system for the broadcast and automatic reception of maritime safety information by means of narrow-band direct-printing telegraphy. [14] |
| 1009 | Neaped | See beneaped. [14] |
| 1010 | Nekton | Those animals of the pelagic division that are active swimmers, such as most of the adult squids, fishes, and marine mammals. [14] |
| 1011 | Nexrad | An acronym for next generation weather radar. The main component of nexrad is the wsr 88-d, doppler radar. [1] |
| 1012 | Octant | A double-reflecting instrument for measuring angles. It is similar to a sextant but has an arc of only 45°. [14] |
| 1013 | Pebble | A small stone worn smooth and rounded by the action of water, sand, ice, etc. Ranging in diameter between 4 and 64 millimeters. [14] |
| 1014 | Pinger | A battery powered acoustic device equipped with a transducer that transmits sound waves. When the pinger is attached to a wire and lowered into the water, the direct and bottom reflected sound can be monitored with a listening device. The difference between the arrival time of the direct and reflected waves is used to compute the distance of the pinger from the ocean bottom. [14] |
| 1015 | Saddle | A broad pass or col, resembling in shape a riding saddle in a ridge or between contiguous elevations. [14] |
| 1016 | Schist | A foliated metamorphic rock which can be split into thin flakes or flat lenticles. Schists are usually named from the dominant mineral, e.g. Mica schist. [14] |
| 1017 | Scoria | (pl. Scoriae). Volcanic rock fragments usually of basic composition, characterized by marked vascularity, dark colour, high density, and a partly crystalline texture. [14] |
| 1018 | Seiche | A standing wave oscillation of an enclosed or semi-enclosed water body that continues, pendulum fashion, after the cessation of the originating force, which may have been either seismic, atmospheric, or wave induced. [14] |
| 1019 | Strays | In echo sounding, false indications occasionally appearing on the dial or fathogram of an echo sounder. They may be caused by the motion of the vessel through the water, by acoustic or electric noises in the ship, or by electric noises in the echo sounding equipment. Strays may be mistaken for the true echo or may be of such a nature as to prevent the identification of the true echo. [14] |
| 1020 | Sunset | The crossing of the apparent horizon by the upper limb of the descending sun. [14] |
| 1021 | Syzygy | In astronomy, either of two opposing points in the orbit of a planet or satellite, especially of the moon, at which it is in conjunction with or in opposition to the sun. [14] |
| 1022 | Trench | A long narrow, characteristically very deep and asymmetrical depression of the sea floor with relatively steep sides. [14] |
| 1023 | Upland | The higher ground of a region contrasted with the valleys and plains. Used in contrast to lowland. [14] |
| 1024 | Upwind | (Adj. & adv.). In the direction from which the wind is blowing. The opposite is downwind. [14] |
| 1025 | Window | In computer applications, a rectangular subdivision of the screen showing information without affec-ting other parts of the screen; a method allowing to view different items of information (e.g. Different data sets or graphics) at the same time. On graphical displays a window may be selected with the cursor and subsequently be enlarged (zoom). [14] |
| 1026 | X-Axis | A horizontal axis in a system of rectangular coordinates; that line on which distances to the right or left (east or west) of the reference line are marked, especially on a map, chart, or graph. [14] |
| 1027 | Benthos | The category of marine organisms that live on, in, or close to the bottom of the oceans. [14] |
| 1028 | Bollard | Small, shaped post, mounted on a wharf or dolphin used to secure ship's lines. Also see mooring. [14] |
| 1029 | Ceiling | See height of cloud base. [14] |
| 1030 | Cinders | Fragments formed when magma is blown into the air; larger in size than volcanic ash. Cinders are a constituent of certain marine sediments. [14] |
| 1031 | Easting | The distance a craft makes good to the east. The opposite is westing. In a cartesian reference system the value of one coordinate, usually expressed in meters, measured from the central meridian in east-west direction; used e.g. In the UTM system. [14] |
| 1032 | Ecology | The science of the economy of animals and plants dealing with the relations of living organism to their surroundings. [14] |
| 1033 | Estuary | That portion of a stream influenced by the tide of the body of water into which it flows. A bay, as the mouth of a river, where the tide meets the river current. [14] |
| 1034 | Eyewall | A wall of dense thunderstorms that surrounds the eye of a hurricane. [1] |
| 1035 | Flotsam | See jettison. [14] |
| 1036 | Fouling | The mass of living and non-living bodies and particles attached to or lying on the surface of a submerged man-made or introduced object; more commonly considered to be only the living or attached bodies. [14] |
| 1037 | Gibbous | Adj.). See phases of the moon. [14] |
| 1038 | Headway | Motion in a forward direction. Also called seaway. [14] |
| 1039 | Hillock | A small hill. [14] |
| 1040 | Ice Age | The most recent period of extensive continental glaciation that saw large portions of north America and Europe covered with ice. It began about 2 million years ago and ended about 10,000 years ago. See pleistocene epoch. [1] |
| 1041 | Ice Fog | See fog. [14] |
| 1042 | Icefoot | A narrow strip of ice attached to the coast, unmoved by tides and remaining after the fast ice has broken free. [14] |
| 1043 | Imagery | Techniques to obtain, process or interpret images created by different types of radiation, e.g. Light, infrared, x-rays. [14] |
| 1044 | Insular | Of or pertaining to an island or islands. [14] |
| 1045 | Isogram | That line on a chart or diagram connecting points having equal values of same phenomenon. [14] |
| 1046 | Isoline | A line representing the intersection of the plane of a vertical photograph with the plane of an overlapping oblique photograph. If the vertical photograph were tilt-free, the isoline would be the isometric parallel of the oblique photograph. [14] |
| 1047 | Moonbow | Rainbow whose formation is the same as that of the ordinary rainbow, but whose light comes from the moon and not from the sun. Also called lunar rainbow. [14] |
| 1048 | New Ice | A general term which includes frazil ice, slush, sludge, pancake ice and ice rind. [14] |
| 1049 | Overlay | In mapping, a record on a transparent medium to be superimposed on another record. [14] |
| 1050 | Polygon | A non-self-intersecting, closed chain defining the boundary of an area. [14] |
| 1051 | Polynia | A water area enclosed in ice, generally fast; this water area remains constant and usually has an oblong shape; sometimes limited to one side by the coast. Any enclosed sea water area in pack ice other than a lead, not large enough to be called open water. If a polynia is found in the same region every year, for example, off the mouths of big rivers, it is called a recurring polynia. A temporary small clearing in pack ice which consists of small ice floes and brash ice in continuous local movement is called an unstable polynia; an opening which is flanked by large floes and therefore appears to be relatively stable is called a stable polynia. When frozen over, a polynia becomes an ice skylight from the point of view of the submariner. [14] |
| 1052 | Rip-Rap | See groin. [14] |
| 1053 | Scanner | A device for directing a beam of radiant energy successively over all points of a given region. In data processing a photo-electronic device for digital reproduction of pictures. The picture is scanned line wise and decomposed into a matrix-like raster of individual pixels. In contrast to vectorial digitizers, the information to coherent elements of the picture (lines, symbols) is lost by this rasterization process. To retrieve these elements the rasterized picture has to be vectorized by pattern recognition methods and manual post-processing. [14] |
| 1054 | Slipway | The prepared and usually reinforced inclined surface on which keel- and bilge-blocks are laid for supporting a vessel under construction. [14] |
| 1055 | Spicule | A minute needlelike or multiradiate calcareous or siliceous body in sponges, radiolarians, primitive chitons, and echinoderms. They frequently are identified in marine sediment samples. [14] |
| 1056 | Stratus | A low, gray cloud layer with a rather uniform base whose precipitation is most commonly drizzle. [1] |
| 1057 | Sunrise | The crossing of the apparent horizon by the upper limb of the ascending sun. [14] |
| 1058 | Swinger | See fix: circular. [14] |
| 1059 | Tagline | A line, either marked at equal intervals or run over a registered sheave, used in large-scale surveys to take equally spaced soundings at predetermined distances from the control stations. [14] |
| 1060 | Tie Net | See triangulation net. [14] |
| 1061 | Topmark | A characteristic shape secured at the top of a buoy or beacon to aid in its identification. [14] |
| 1062 | Torrent | Rushing stream of water; great downpour of rain. [14] |
| 1063 | Typhoon | Name given to tropical cyclones of the china sea and, more generally, of the north-west pacific. [14] |
| 1064 | Variate | A variate is a quantity that may take on any of the values of a specified set with a specified relative frequency or probability often known as random variable. It is to be regarded as defined not merely by a set of permissible values, but by an associated frequency (probability) function expressing how often those values appear in a given situation. [14] |
| 1065 | Abrasion | The wearing away or rounding of surfaces by friction. [14] |
| 1066 | Aeronomy | Term proposed for the study of the chemistry and physics of the high atmosphere. [14] |
| 1067 | Aliasing | An occurrence in tidal analysis when the sea level varies with a period that is less than the sampling period. Due to the varying position of the samples on the curve, a spurious tidal frequency appears in the analysis. It is usually only possible when there is a seiche at the observation site or observations are taken at intervals greater than one hour. [14] |
| 1068 | Base Net | See base extension triangulation. [14] |
| 1069 | Bow Echo | A line of thunderstorms on a radar screen that appears in the shape of a bow. Bow echoes are often associated with damaging straight-line winds and small tornadoes. [1] |
| 1070 | Bridging | See stereo triangulation. [14] |
| 1071 | Can Buoy | A buoy the above-water part of which is in the shape of a cylinder. Sometimes called cylindrical buoy. [14] |
| 1072 | C-Factor | (US Terminology). In photogrammetry, an empirical value which expresses the vertical measuring capability of a given stereoscopic system; generally defined as the ratio of the flight height to the smallest contour interval accurately plottable. The c-factor is not a fixed constant but varies over a considerable range, according to the elements and conditions of the photogrammetric system. In planning for aerial photography, the c-factor is used to determine the flight height required for a specified contour interval, camera, and instrument system. [14] |
| 1073 | Clearing | See clearance. [14] |
| 1074 | Compiler | A program that translates programs from one programming language (source program) into another programming language (object program). Typically, the compiler translates from a higher, user understandable language to a lower, machine interpretable language. [14] |
| 1075 | Crescent | Adj.). See phases of the moon. [14] |
| 1076 | Dan Buoy | A buoy consisting of a ballasted float carrying a staff which supports a flag or light. [14] |
| 1077 | Derelict | Any property abandoned at sea, often of sufficient size as to constitute a menace to navigation, especially an abandoned vessel. See wreck. [14] |
| 1078 | Ebb Tide | See tide: falling. [14] |
| 1079 | Echogram | A graphic record of depth measurements obtained by an echo sounder. See fathogram. [14] |
| 1080 | Eelgrass | See seagrass. [14] |
| 1081 | Epipoles | In the perspective set-up of two photographs, (two perspective projections), the points on the planes of the photographs where they are cut by the air base. [14] |
| 1082 | Evection | A perturbation of the moon in its orbit due to the attraction of the sun. See also lunar inequality. [14] |
| 1083 | Eye Base | See interpupillary distance. [14] |
| 1084 | F-Number | See aperture: relative. [14] |
| 1085 | Gustnado | A relatively weak tornado associated with a thunderstorm's outflow. It most often forms along the gust front. [1] |
| 1086 | Hachures | Short lines drawn on a chart or map for representing relief. These lines are drawn in the direction of the slope and intensified on the shaded side of the feature assuming the area is illuminated from the north-west. Unlike the contour lines, they give no indication of the actual height of land above sea level. See also hill shading. [14] |
| 1087 | Headland | A high steep promontory. Usually called head when coupled with a specific name. [14] |
| 1088 | Ice Floe | See floe. [14] |
| 1089 | Ice Rind | A thin, elastic, shining crust of ice, formed by the freezing of sludge on a quiet sea surface. Thickness less than 5 cm. [14] |
| 1090 | Icebound | (Adj.). Said of a harbor, inlet, etc. When navigation by ships is prevented due to ice, except possibly with the assistance of an icebreaker. Of a ship, surrounded so closely by ice as to be incapable of proceeding. [14] |
| 1091 | Isopleth | An isogram of equal or constant value of a given quantity, with respect to either time or space. [14] |
| 1092 | Isotherm | In meteorology, the line which is the locus of points which have the same value of air temperature. [14] |
| 1093 | Jettison | The throwing overboard of objects, especially to lighten a craft in distress. Jettisoned objects that float are termed flotsam; those that sink, jetsam; and heavy articles that are buoyed for future recovery, lagan. See derelict. [14] |
| 1094 | Landfall | The first sighting of land when approached from seaward. By extension, the term is sometimes used to refer to the first contact with land by any means, as by radar. [14] |
| 1095 | Layering | A method of emphasizing on a chart differences in height or depth by use of varying tints. Also referred to as layer tinting. [14] |
| 1096 | Log Chip | The wooden quadrant forming part of a chip log. Also called log ship. [14] |
| 1097 | Lunation | See month: synodical. [14] |
| 1098 | Mainland | The principal land or largest part of a continent, as distinguished from a relatively small island or peninsula. [14] |
| 1099 | Marigram | See tide curve. [14] |
| 1100 | Masthead | The top of a mast. [14] |
| 1101 | Northing | The distance a craft makes good to the north. The opposite is southing. In a cartesian reference system the value of one coordinate, usually expressed in meters, measured from the origin in north-south direction; used e.g. In the UTM system. [14] |
| 1102 | Nutation | Irregularities in the precessional motion of the equinoxes because of varying positions of the moon, and, to a lesser extent, of other celestial bodies, with respect to the ecliptic. Because of nutation the earth's axis nods like a top, describing an irregular circle about the mean pole in a period of about 19 years. [14] |
| 1103 | Odograph | A mechanical instrument containing a distance-measuring element which is moved or turned by an amount proportional to the actual distance travelled; a compass element which provides a fixed-reference direction, and an integrator which provides for the resolution of the direction of motion into components and for the summation or integration of the distance components. Also, an instrument for recording the distance travelled by a vehicle or pedestrian. [14] |
| 1104 | Overtide | A shallow water harmonic tide constituent with a speed that is a multiple of the speed of one of the basic constituents of the tide-producing force. See harmonic constituent, and shallow water constituent. [14] |
| 1105 | Photomap | A photomosaic of a specified land area, which also contains marginal information, descriptive data, and a reference grid and/or projection. See also mosaic. [14] |
| 1106 | Piedmont | (Adj.). Situated or formed at the base of mountains. [14] |
| 1107 | Pigments | A colouring matter used as paint or dye or a natural colouring matter of a tissue. [14] |
| 1108 | Province | In oceanography and in a morphological sense, a region composed of a group of similar physiographic features whose characteristics are markedly in contrast with surrounding areas (rarely used in marine cartography). [14] |
| 1109 | Red Tide | A red or reddish-brown discoloration of surface waters, most frequently in coastal regions, caused by concentration of certain microscopic organisms, particularly dinoflagellates. Toxins produced by the dinoflagellates can cause mass kills of fishes and other marine animals. [14] |
| 1110 | Revolver | See fix: circular. [14] |
| 1111 | Sea Buoy | See farewell buoy. [14] |
| 1112 | Sea Mile | The length of one minute of arc, measured along the meridian in the latitude of the position; its length varies both with the latitude and with the figure of the earth in use. Used in navigation to measure distances on sea charts using the Mercator projection. Not to be confused with nautical mile or international nautical mile. [14] |
| 1113 | Sea Wall | An embankment or wall for protection against waves or tidal action along a shore or water front. [14] |
| 1114 | Seagrass | Any grass like marine alga. Eelgrass is one of the best known seagrasses. [14] |
| 1115 | Shallows | An indefinite term applied to expanses of shoal or shallow water. [14] |
| 1116 | Stellite | A trade name for an alloy of chromium, cobalt and tungsten. Stellate mirrors, free of imperfection and practically indestructible, are frequently used in hydrographic sextants. See sextant: sounding. [14] |
| 1117 | Stranded | (1) the terms "stranded" and "sunken" apply exclusively to items that once were afloat but which are now resting on the bottom. Stranded items project above the sounding datum while sunken items do not project above the sounding datum. These terms apply most often to wrecks. Masts, funnels, and other extensions of wreck superstructure should be disregarded when applying the above definition; i.e., such features may project above the sounding datum and still have the wreck classified as sunken. (2) the grounding of a vessel so that it is not soon refloated; a serious grounding. [14] |
| 1118 | Tideland | Land which is under water at high tide and uncovered at low tide. [14] |
| 1119 | Time Tag | Reference assigned to each measurement input from a sensor to identify the time (either cpu, gps, or utc) when a measurement was actually made by that particular sensor; time tags allow adjustment of data from different sensors to a common time reference. [14] |
| 1120 | True Sun | See sun: apparent. [14] |
| 1121 | Waveform | The graphical representation of a wave, showing variation of amplitude with time. Also written as two words. [14] |
| 1122 | Wetlands | The term "wetlands" means those areas that are inundated or saturated by surface or ground water at a frequency and duration sufficient to support, and that under normal circumstances do support, a prevalence of vegetation typically adapted for life in saturated soil conditions. Wetlands generally include swamps, marshes, bogs and similar areas. [14] |
| 1123 | Acclivity | An upward slope of ground; as opposed to declivity. [14] |
| 1124 | Acid Rain | Cloud droplets or raindrops combining with gaseous pollutants, such as oxides of sulfur and nitrogen, to make falling rain (or snow) acidic pH less than 5.0. If fog droplets combine with such pollutants it becomes acid fog. [1] |
| 1125 | Air Speed | The speed of an aircraft relative to the surrounding atmosphere. As opposed to ground speed. [14] |
| 1126 | Backbeach | Also written as two words. See backshore. [14] |
| 1127 | Bar Scale | See scale. [14] |
| 1128 | Basepoint | A basepoint is any point on a baseline. [14] |
| 1129 | Blackbody | A hypothetical object that absorbs all of the radiation that strikes it. It also emits radiation at a maximum rate for its given temperature. [1] |
| 1130 | Box Gauge | See gauge: float. [14] |
| 1131 | Capacitor | See condenser. [14] |
| 1132 | Data Bank | A collection of data in a common location, relating to a given set of subjects. Usually comprised of several data bases considered as an entity. [14] |
| 1133 | Daybeacon | An unlighted beacon. A day beacon is identified by its colour, shape, and number of its daymark. The simplest form of day beacon consists of a single pile with a daymark affixed at or near its top. [14] |
| 1134 | Decimetre | One-tenth of a metre. [14] |
| 1135 | Declivity | A downward slope or sloping of a hill; as opposed to acclivity. [14] |
| 1136 | Depth Ice | See anchor ice. [14] |
| 1137 | Dock: Dry | An artificial basin fitted with a gate or caisson, into which vessels can be floated and the water pumped out to expose the vessel's bottom. Also called graving dock. [14] |
| 1138 | Downburst | A severe localized downdraft that can be experienced beneath a severe thunderstorm. (compare microburst and macroburst.) [1] |
| 1139 | Draft Aft | See draft. [14] |
| 1140 | Echometer | (France). An ultrasonic echo sounder with a visual depth-indicating device. The signals are produced and received by quartz-crystal transmitting and receiving units. Its range is from 6 to 660 meters. [14] |
| 1141 | Echoscope | (France). An ultrasonic echo sounder similar to echometer. The echoscope is portable, intended for shoal-water sounding from small boats. Its range is from 1 to 60 meters. [14] |
| 1142 | Facsimile | An exact reproduction or copy. [14] |
| 1143 | Fathogram | A graphic record of depth measurements obtained by a fathometer (erroneously applied to any echogram). [14] |
| 1144 | Fish Farm | An assemblage of cages, nets, rafts and floats or posts where fish, including shellfish, are artificially cultivated. [14] |
| 1145 | Foreshore | That part of shore which lies between high and low water mark at ordinary tide. [14] |
| 1146 | Foresight | In levelling, a reading on a levelling rod held on a point whose elevation is to be determined. See also backsight. [14] |
| 1147 | Grivation | See variation: grid. [14] |
| 1148 | Hailstone | Globule or piece of ice, with a diameter varying between 5 and 50 mm or even more, the fall of which constitutes hail. Hailstones consist almost entirely of transparent ice, or of a series of layers of transparent ice with a thickness of at least 1 mm, alternating with translucent layers. [14] |
| 1149 | Half Tide | See tide. [14] |
| 1150 | Hard Iron | Iron or steel which is not readily magnetized by induction, but which retains a high percentage of the magnetism acquired. The opposite is soft iron. [14] |
| 1151 | High Noon | See noon: local apparent. [14] |
| 1152 | Hoarfrost | Deposit of ice, having a crystalline appearance, generally assuming the form of scales, needles, feathers or fans. Hoarfrost is produced in a manner similar to dew but at a temperature below 0°c. Also written as two words. [14] |
| 1153 | Hodograph | Used in oceanography. The tidal current vector hodograph is the figure traced out by the tip of a vector representing the current over the tidal cycle. [14] |
| 1154 | Hydrology | The scientific study of the waters of the earth, especially with relation to the effects of precipitation and evaporation upon the occurrence and character of water in streams, lakes, and on or below the land surfaces. [14] |
| 1155 | Ice Front | The vertical cliff forming the seaward face of an ice shelf. See ice wall. [14] |
| 1156 | Ice Shelf | A floating ice sheet of considerable thickness. Ice shelves are usually of great horizontal extent and have a level or gently undulating surface. They are nourished by local snow accumulation and often also by the seaward extension of land glaciers. Limited areas may be aground. The initial stage is called bay ice until the surface is more than about 2 m above sea level. The seaward edge is termed an ice front. [14] |
| 1157 | Isometric | (Adj.). Of or pertaining to equal measure. [14] |
| 1158 | Jellyfish | Any of various free-swimming coelenterates having a disc- or bell-shaped body of jellylike consistency. Many have long tentacles with nematocysts (stinging cells). Some are capable of producing glowing ball luminescence. Any jellylike free-floating organism. The term 'jellyfish' often is applied to the ctenophores and may be applied to certain tunicates. Also called medusa. [14] |
| 1159 | Land Mile | See statute mile. [14] |
| 1160 | Lee Shore | Shore that is to leeward of a vessel. See weather shore. [14] |
| 1161 | Lens Axis | See axis of lens. [14] |
| 1162 | Level Net | Lines of spirit levelling connected together to form a system of loops and circuits extending over an area. Also called survey net. [14] |
| 1163 | Limnology | The scientific study of the biological, chemical, geographical, and physical features of fresh waters, especially of lakes and ponds. [14] |
| 1164 | Loxodrome | A curve, on the surface of a sphere, intersecting all great circles of the sphere at a constant oblique angle, theoretically never reaching the pole while closely approaching it. See rhumb line. [14] |
| 1165 | Lunar Day | See day. [14] |
| 1166 | Megahertz | One million hertz; one thousand kilohertz. The term is used as the equivalent of one million cycles per second. [14] |
| 1167 | Milky Way | A broad, faintly luminous band seen across the sky at night, consisting of innumerable stars and nebulae, so distant as to be indistinguishable without a telescope. [14] |
| 1168 | Nearshore | Close to the shore. [14] |
| 1169 | Noctiluca | A genus of usually pale pink luminescent dinoflagellates large enough to be seen by the unaided eye. This particular organism is responsible for much of the sheet-type luminescence noted in coastal waters of various parts of the world ocean. [14] |
| 1170 | Occlusion | Process of progressive decrease of area of warm sector at the earth's surface, and its ultimate disappearance, by the junction of the cold air masses which initially precede the warm front and follow the cold front. Front between these two cold air masses, after their junction (also termed occluded front). [14] |
| 1171 | Pedometer | A pocket-size instrument which registers in linear units the distance traversed by the pedestrian carrying it. See passometer. [14] |
| 1172 | Peninsula | A piece of land that is almost an island, being nearly surrounded by water; by extension any piece of land projecting into the sea, so that the greater part of its boundary is coastline. [14] |
| 1173 | Phase Lag | Angular retardation of the maximum of a constituent of the observed tide behind the correspon-ding maximum of the same constituent of the hypothetical equilibrium tide. Also called tidal epoch. [14] |
| 1174 | Planetoid | See asteroid. [14] |
| 1175 | Processor | See microprocessor. [14] |
| 1176 | Range Rod | A simple surveyor's rod, fitted with a sharp-pointed steel shoe. It is usually painted red and white alternately, and used to line up points of a survey. [14] |
| 1177 | Reef Flat | A flat expanse of dead reef rock which is partly or entirely dry at low tide. [14] |
| 1178 | Remanence | See magnetic retentivity. [14] |
| 1179 | Resonance | Re-enforcement or prolongation of any wave motion, such as sound, radio waves, etc., resulting when the natural frequency of the body or system in vibration is equal to that of an impressed vibration. In tides, the water movement resulting from the natural period of oscillation of a body of water which approximates the period of one of the tide-producing forces. [14] |
| 1180 | Responder | A transmitter, fitted to a submersible or on the seabed, which can be triggered by a hardwired external control signal to transmit an interrogation signal which is received by a transducer or hydrophone. [14] |
| 1181 | Revetment | Facing of stone or other material, either permanent or temporary, placed along the edge of a stream to stabilize the bank and to protect it from the erosive action of the stream. [14] |
| 1182 | Sea Reach | The straight part of a river between the last bend and the sea. [14] |
| 1183 | Side Shot | A reading or measurement from a survey station to locate a point which is not intended to be used as a base for the extension of the survey. A side shot is usually made for the purpose of determining the position of some object which is to be shown on the map. [14] |
| 1184 | Snowstorm | Storm of blowing snow. [14] |
| 1185 | Telemeter | An instrument for determining the distance from one point to another. Some such instruments employ a telescope and measure the angle subtended by a short base of known length. The complete equipment for measuring any quantity, transmitting the results electrically to a distance point, and there recording the values measured. [14] |
| 1186 | Threshold | In aeronautical terminology, the beginning of that portion of the runway usable for landing. [14] |
| 1187 | Tide Lock | A lock situated between a basin or canal and tidewater to maintain the water at a desired level as the height of the tide changes. Also called guard lock. [14] |
| 1188 | Tide Pole | See tide staff. [14] |
| 1189 | Tidewater | Water affected by tides or sometimes that part of it which covers the tideland. The term is sometimes used broadly to designate the seaboard. See tidal waves. [14] |
| 1190 | Timepiece | An instrument for measuring time. See chronometer, clock, watch. [14] |
| 1191 | Tributary | A river which joins a larger one. [14] |
| 1192 | Tunny Net | A net built at sea for catching tunnies. [14] |
| 1193 | Washovers | Small deltas formed on the lagoon side of a bar separating the lagoon from the open sea. Storm waves breaking over the bar deposit sediment on the lagoon side in the form of deltas. Also called wave deltas. [14] |
| 1194 | Watershed | Water-parting. The whole region or area contributing to the supply of a river or lake; drainage area; catchment area or basin. [14] |
| 1195 | Wind Rose | For a given station and period of time, a star-shaped diagram indicating the relative frequencies of different directions of wind, sometimes also the frequencies of groups of wind speeds in different directions. [14] |
| 1196 | Wind Tide | See wind set-up. [14] |
| 1197 | Almucantar | Any small circle on the celestial sphere parallel to the horizon. Also called parallel of altitude. [14] |
| 1198 | Barysphere | See centrosphere. [14] |
| 1199 | Blind Seas | See blind rollers. [14] |
| 1200 | Blind Zone | An area within or from which little or no radio signal is received. Also called zone of silence. [14] |
| 1201 | Breakwater | A structure protecting a shore area, harbor, anchorage, or basin from waves. See also floating breakwater. [14] |
| 1202 | Challenger | See interrogator. [14] |
| 1203 | Chromatism | See aberration of light. [14] |
| 1204 | Clinometer | An instrument for indicating the degree of slope or the angle of roll or pitch of a vessel, according to the plane in which it is mounted. [14] |
| 1205 | Cocked Hat | Triangle on chart, formed by three position lines that do not cross at one point. Also called triangle of error. Note. This expression is seldom used by american navigators. [14] |
| 1206 | Compacting | Pieces of sea ice are said to be compacting when they are subjected to a converging motion, which increases ice concentration and/or produces stresses which may result in ice deformations. [14] |
| 1207 | Compensate | (v.t.). To counteract an error, as in an instrument; to counterbalance. [14] |
| 1208 | Daily Rate | See chronometer rate. [14] |
| 1209 | Datum Line | See reference line. [14] |
| 1210 | Day Number | The sequentially numbered day of the year, usually starting with day number 1 on 1st January. [14] |
| 1211 | Definition | In photography, and electronic equipment, the degree of clarity and sharpness of an image. See resolution and resolving power. [14] |
| 1212 | Dove Prism | A prism which reverts the image but does not deviate nor displace the beam. A given angular rotation of the prism about its longitudinal axis causes the image to rotate through twice the angle. Also called a rotating prism. [14] |
| 1213 | Downstream | (Adj. and Adv.). In the direction of flow of a current or stream. The opposite is upstream. [14] |
| 1214 | Earthshine | See earth light. Also written as two words. [14] |
| 1215 | Embankment | An artificial elevation composed of earth, stone, etc. To hold back water. [14] |
| 1216 | Escarpment | An elongated, characteristically linear, steep slope, separating horizontal or gently sloping sectors of the sea floor in non-shelf areas. Also abbreviated to scarp. [14] |
| 1217 | False Echo | See echo. [14] |
| 1218 | Field Work | All activities in the field required for a hydrographic survey. [14] |
| 1219 | Flood Tide | See tide: rising. [14] |
| 1220 | Frazil Ice | Fine spicules or plates of ice in suspension in water. [14] |
| 1221 | Grease Ice | A later stage of freezing than frazil ice when the crystals have coagulated to form a soupy layer on the surface. Grease ice reflects little light, giving the sea a matt appearance. [14] |
| 1222 | Hack Watch | See watch. [14] |
| 1223 | Heat Burst | A sudden increase in surface air temperature often accompanied by extreme drying. A heat burst is associated with the downdraft of a thunderstorm, or a cluster of thunderstorms. [1] |
| 1224 | Heliograph | A device for reflecting the sun's rays from one point to another for sending messages. In meteorology, instrument which records the time interval during which solar radiation reaches sufficient intensity to cast distinct shadows. Also called sunshine recorder. [14] |
| 1225 | Heliotrope | See heliostat. [14] |
| 1226 | Hygrograph | Hygrometer which includes an arrangement for the time recording of atmosphere humidity. [14] |
| 1227 | Hypsograph | A circular instrument of the slide-rule type used to compute elevations from vertical angles and horizontal distances. [14] |
| 1228 | Hypsometer | A device for measuring heights of land surfaces by the boiling point of water. [14] |
| 1229 | Julian Day | The number of each day, as reckoned consecutively since the beginning of the present Julian period on January 1, 4713 BC. The Julian day begins at noon, 12 hours later than the corresponding civil day. [14] |
| 1230 | Landlocked | (Adj.). Almost or quite enclosed by land. Said of an area of water, as a bay, harbor, etc., entirely protected from the sea. [14] |
| 1231 | Large Halo | See halo. [14] |
| 1232 | Level Axis | See axis of spirit level. [14] |
| 1233 | Light Beam | A group of pencils of light, as those originating at the many points of an illuminated surface. A beam of parallel light rays is a special case in which each pencil is of such small cross-section that it may be regarded as a ray. [14] |
| 1234 | Log Factor | The ratio represented by the true distance divided by the log distance. [14] |
| 1235 | Lower Limb | See limb. [14] |
| 1236 | Mean Draft | See draft. [14] |
| 1237 | Mesosphere | The atmospheric layer between the stratosphere and the thermosphere. Located at an average elevation between 50 and 80 km above the earth's surface. [1] |
| 1238 | Oceanology | See oceanography. [14] |
| 1239 | Open Coast | A coast that is not sheltered from the sea. [14] |
| 1240 | Orthodrome | Any line on a chart representing a great circle track between two points. [14] |
| 1241 | Orthogonal | (Adj.). At right angles; rectangularly meeting, crossing, or lying at right angles. [14] |
| 1242 | Patent Log | See log. [14] |
| 1243 | Permafrost | A layer of soil or bedrock at a variable depth beneath the surface of the earth in which the temperature has been below freezing continuously from a few to several thousands of years. Permafrost exists where the summer heating fails to descend to the base of the layer of frozen ground. [14] |
| 1244 | Radiosonde | Instrument carried through the atmosphere, equipped with devices permitting one or several meteorological elements (pressure, temperature, humidity, etc.) To be determined, and provided with a radio transmitter for sending this information. [14] |
| 1245 | Rafted Ice | Type of pressure ice formed by one floe overriding another. [14] |
| 1246 | Rear Light | See light(s): range. [14] |
| 1247 | Red Sector | A sector of the circle of visibility of a navigational light in which a red light is exhibited. Such sectors are designated by their limiting bearings, as observed at some point other than the light. Red sectors are often located so that they warn of danger to vessels. [14] |
| 1248 | Roof Prism | A type of prism in which the image is reverted by a roof, that is, two surfaces inclined at 90° to each other. [14] |
| 1249 | Seismology | The science and study of earthquakes, and their causes and effects and related phenomena. [14] |
| 1250 | Settlement | The general lowering in level of a moving vessel, relative to what its level would be were it motionless. Settlement is due to the regional depression of the surface of the water in which the ship moves. It is not an increase in displacement. Settlement is a factor to be reckoned in echo sounding. [14] |
| 1251 | Sight Line | See collimation: line of. [14] |
| 1252 | Slack Tide | See slack water. [14] |
| 1253 | Solar Year | See year: tropical. [14] |
| 1254 | Sonic Wave | See wave: sound. [14] |
| 1255 | Sound Buoy | See buoy. [14] |
| 1256 | Speed Line | A line of position approximately perpendicular to the course. [14] |
| 1257 | Stadia Rod | See stadia. [14] |
| 1258 | Star Globe | A small globe representing the celestial sphere, on which the apparent positions of the stars are indicated. It is usually provided with graduated arcs and a suitable mount for determining the approximate altitude and azimuth of the stars, to serve as a star finder. Also called celestial globe. [14] |
| 1259 | Steel Tape | See tape. [14] |
| 1260 | Stereopair | See stereoscopic pair. [14] |
| 1261 | Stop Watch | See watch. [14] |
| 1262 | Storm Tide | See storm surge. [14] |
| 1263 | Storm Wave | See wave. [14] |
| 1264 | Sugar Loaf | A descriptive term for a conical hill. [14] |
| 1265 | Survey Net | See level net, triangulation net. [14] |
| 1266 | Tachymetry | A method of surveying for the rapid determination of distance, direction, and relative elevation of a point with respect to the instrument station by a single observation on a rod or other object at the point. The stadia method of surveying is an example of tachymetry. [14] |
| 1267 | Tented Ice | Pressure ice in which two ice floes have been pushed into the air, leaving an air space underneath. [14] |
| 1268 | Tidal Rise | See rise of tide. [14] |
| 1269 | Variometer | An instrument for comparing magnetic forces, especially of the earth's magnetic field. [14] |
| 1270 | Wall Cloud | An area of rotating clouds that extends beneath a supercell thunderstorm and from which a funnel cloud may appear. Also called a collar cloud and pedestal cloud. [1] |
| 1271 | Warm Front | Any non-occluded front which moves in such a way that warmer air replaces colder air. [14] |
| 1272 | Watch Buoy | See station buoy. [14] |
| 1273 | Wave Group | A series of waves in which the wave direction, wavelength, and wave height vary only slightly. [14] |
| 1274 | Westerlies | One, lying between the approximate latitudes 35oand 65o in each hemisphere, in which the air motion is mainly from west to east, especially in the high troposphere and low stratosphere. Near the earth's surface, the zone is particularly well marked in the southern hemisphere. [14] |
| 1275 | Westerlies | The dominant westerly winds that blow in the middle latitudes on the poleward side of the subtropical high- pressure areas. [1] |
| 1276 | X-Parallax | See parallax: absolute stereoscopic. [14] |
| 1277 | Age Of Tide | See age of phase inequality. [14] |
| 1278 | Aiming Line | See collimation: line of. [14] |
| 1279 | Air Density | The ratio of the mass of a substance to the volume occupied by it. Air density is usually expressed as g/cm3 or kg/m3. Also see density. [1] |
| 1280 | Air Sextant | See sextant. [14] |
| 1281 | Altocumulus | A middle cloud, usually white or gray. Often occurs in layers or patches with wavy, rounded masses or rolls. [1] |
| 1282 | Altostratus | A middle cloud composed of gray or bluish sheets or layers of uniform appearance. In the thinner regions, the sun or moon usually appears dimly visible. [1] |
| 1283 | Anticyclone | Region of the atmosphere where the pressure is high relative to the surrounding region at the same level. It is represented on a synoptic chart by a system of isobars at a specified level or of contours at a specified pressure which enclose relatively high values of pressure or level. Also called high. [14] |
| 1284 | Area Survey | A method of bottom relief survey consisting of surveying overlapping strips which allow soundings to be obtained with a specified accuracy at any position of the area under survey. [14] |
| 1285 | Astigmatism | An aberration affecting the sharpness of images for objects off the axis, in which the rays passing through different meridians of the lens come to focus in different planes. [14] |
| 1286 | Attenuation | A lessening in amount, particularly the reduction of the amplitude of a wave or the intensity of light or sound with distance from the origin. [14] |
| 1287 | Basal Plane | See epipolar plane. [14] |
| 1288 | Bifurcation | A division into two branches. [14] |
| 1289 | Box Compass | See declinatoire. [14] |
| 1290 | Buoy: Sound | A buoy equipped with a characteristic sound signal. Sound buoys may be further classified according to the manner in which the sound is produced, such as bell, gong, horn, trumpet, or whistle buoy. [14] |
| 1291 | Buoy: Super | A very large buoy designed to carry a signal light of high luminous intensity at a high elevation. See also large automatic navigation buoy (lanby). [14] |
| 1292 | Check Angle | A third angle taken to a fourth point as a check to a three-point fix. [14] |
| 1293 | Coast Pilot | (US Terminology). A descriptive book for the use of mariners, containing detailed information of coastal waters, harbor facilities, etc., of an area. Such books are prepared by the national ocean service for waters of the US. And its possessions. See also sailing directions. [14] |
| 1294 | Correlation | The removal of discrepancies that may exist among survey data, so that all parts are interrelated without apparent error. [14] |
| 1295 | Cross Hairs | See cross wires. [14] |
| 1296 | Danger Zone | See danger area. [14] |
| 1297 | Datum Point | See reference point. [14] |
| 1298 | Delineation | In cartography, the visual selection and distinguishing of map worthy features on various possible source materials by outlining the features on the source material, or on a map manuscript (as when operating a stereoscopic plotting instrument); also a preliminary step in compilation. [14] |
| 1299 | Dipsey Lead | See lead: deep sea. [14] |
| 1300 | Diurnal Arc | See arc: astronomical. [14] |
| 1301 | Drying Reef | A reef or part thereof which dries at low water. [14] |
| 1302 | Forel Scale | A colour scale employed as a means of determining the colour of sea water. [14] |
| 1303 | Front Light | See light(s): range. [14] |
| 1304 | Frost Point | The temperature to which atmospheric moisture must be cooled to reach the point of saturation with respect to ice. [14] |
| 1305 | Grid Method | In photogrammetry, a method of plotting detail from oblique photographs by superimposing a perspective of a map grid on a photograph and transferring the detail by eye, that is, by using the corresponding lines of the map grid and its perspective as placement guides. See also grid: per-spective. [14] |
| 1306 | Hydrosphere | The waters of the earth's surface collectively. The 'water sphere' in comparison and contrast with lithosphere and atmosphere. [14] |
| 1307 | Index Glass | See index mirror. [14] |
| 1308 | Isomagnetic | (Adj.). Of or pertaining to lines connecting points of equality in some magnetic element. [14] |
| 1309 | Isomagnetic | (n.). See isomagnetic line. [14] |
| 1310 | Land Breeze | Wind of coastal regions blowing at night from the land towards a large water surface as a result of nocturnal cooling of the land surface. [14] |
| 1311 | Land Survey | See survey: cadastral. [14] |
| 1312 | Layer Depth | In oceanography, the thickness of the mixed layer; or the depth to the top of the thermocline. [14] |
| 1313 | Marker Buoy | A temporary buoy used in surveying to mark a location of particular interest such as a shoal or reef. See also station buoy. [14] |
| 1314 | Occultation | The concealment or extinguishment of the light of an aid to navigation during the dark periods of its cycle. In astronomy, the concealment of a celestial body by another which crosses the line of view. Thus, the moon occults a star when it passes between the observer and the star. [14] |
| 1315 | Ocean Water | Water having the physical-chemical characteristics of the open sea, where continental influences are at a minimum. [14] |
| 1316 | Planisphere | A map or chart that is the projection of all or part of a sphere on a plane. A representation, on a plane, of the celestial sphere, especially one on a polar projection, with means provided for making certain measurements such as altitude and azimuth. See star finder. [14] |
| 1317 | Plumb Point | See nadir: photograph. [14] |
| 1318 | Radial Plot | See radial triangulation. [14] |
| 1319 | Radio Range | A radio facility the emissions of which are intended to provide a definite course guidance. [14] |
| 1320 | Radio Stars | Sources of radio waves existing in the universe. The position of many of the radio stars have been plotted but their signals are generally very weak. [14] |
| 1321 | Restitution | The process of determining the true planimetric position of objects whose images appear on photographs. Restitution corrects for distortion resulting from both tilt and relief displacement. [14] |
| 1322 | Rip Current | See current. [14] |
| 1323 | Safety Zone | The area around an offshore installation within which vessels are prohibited from entering without permission. Special regulations protect installations within a safety zone and vessels of all nationalities are required to respect the zone. [14] |
| 1324 | Scale Error | The difference between the principal scale and the particular scale resulting from projection distortion. [14] |
| 1325 | Secchi Disc | A white, black, or varicolored disc, 30 centimeters in diameter, used to measure water transparency (clarity). The disc is lowered in the water and the depth (in meters) at which it disappears from sight is averaged with the depth at which it reappears. This average value is used to represent sea water transparency. [14] |
| 1326 | Selenotrope | A device used in geodetic surveying for reflecting the moon's rays to a distant point, to aid in long-distance observations. [14] |
| 1327 | Slope Angle | The angle between a slope and the horizontal. [14] |
| 1328 | Speedometer | An odometer recording the speed of a craft by a process of differentiation. [14] |
| 1329 | Spot Height | See spot elevation. [14] |
| 1330 | Squaring Up | See squares: method of. [14] |
| 1331 | Star Finder | A device to facilitate the identification of stars. Sometimes called a star identifier. See planisphere. [14] |
| 1332 | Stereomodel | See stereoscopic image. [14] |
| 1333 | Stratopause | Top of the inversion layer in the upper stratosphere, at about 50-55 km. [14] |
| 1334 | Summer Time | See time: daylight saving. [14] |
| 1335 | Sumner Line | A celestial line of position, particularly one established by the Sumner method. Named after captain Thomas h. Sumner, the discoverer of the line of position by celestial observation. [14] |
| 1336 | Sunken Rock | A rock potentially dangerous to surface navigation, the summit of which is below the lower limit of the zone for rock awash. [14] |
| 1337 | Tape: Invar | Any survey tape made of invar. [14] |
| 1338 | Tape: Steel | Any survey tape made of steel. [14] |
| 1339 | Tidal Level | Depth or height contours defined by the rise and fall of the astronomical tide. [13] |
| 1340 | Time: Civil | Solar time in a day (civil day) that begins at midnight. [14] |
| 1341 | Transceiver | A combination transmitter and receiver in a single housing, with some components being used by both parts. See transponder. [14] |
| 1342 | Valley Line | See talweg. [14] |
| 1343 | W/T Station | See radio station. [14] |
| 1344 | Waning Moon | See phases of the moon. [14] |
| 1345 | Wave Trough | See trough. [14] |
| 1346 | Wave: Sound | A mechanical disturbance advancing with finite velocity through an elastic medium and consisting of longitudinal displacements of the ultimate particles of the medium, that is, consisting of compressional and rare-factional displacements parallel to the direction of advance of the disturbance; a longitudinal wave. Also called sonic wave, or acoustic wave. [14] |
| 1347 | Waxing Moon | See phases of the moon. [14] |
| 1348 | Wet Compass | See compass: liquid. [14] |
| 1349 | Wind Set-Up | The vertical rise in the still water level on the leeward side of a body of water caused by wind stresses on the surface of the water. The difference in still water levels on the windward and the leeward sides of a body of water caused by wind stresses on the surface of water. Synonymous with wind tide. Wind tide is usually reserved for use on the ocean and large bodies of water. Wind set-up is usually reserved for use on reservoirs and smaller bodies of water. See tide: meteorological. [14] |
| 1350 | Wire: Invar | A wire made of invar metal used in measurement of geodetic bases. [14] |
| 1351 | Grid: Universal Transverse Mercator (Utm) | A grid system in which a grid network is applied to transverse Mercator projections of zones of the earth's surface extending to 80° n. And s. Latitudes. [14] |
| 1352 | d50 | One of the sediment characteristic which is in the median grain size. ; The portions of particles with diameters smaller and larger than this value are 50%. Also known as the median diameter. [24] |
| 1353 | Gut | A narrow passage such as a strait or inlet. A channel in otherwise less deep water, generally formed by water in motion. [14] |
| 1354 | Kay | See cay. [14] |
| 1355 | Ohm | The unit of electrical resistance in the si system. [14] |
| 1356 | Voe | An inlet, bay, or creek. [14] |
| 1357 | Arpa | See automatic radar plotting aid. [14] |
| 1358 | Bias | The distortion of a result through negligence of a factor usually introducing a systematic error of unchanging magnitude and sign throughout a given series of observations. [14] |
| 1359 | Blip | Indication of a signal on the scope of an electronic instrument, produced by a short sharply-peaked pulse of voltage. [14] |
| 1360 | Crag | A steep or precipitous rugged rock. [14] |
| 1361 | Dyke | See dike. [14] |
| 1362 | Firn | Old snow which has become granular and dense under the action of various processes of melting and refreezing, also including sublimation. [14] |
| 1363 | Font | Complete assortment of all the different characters of a particular size and style of type. [14] |
| 1364 | Glen | A narrow, secluded valley. [14] |
| 1365 | Gyre | A closed circulatory system, but larger than a whirlpool or eddy. [14] |
| 1366 | Haze | Suspension in the atmosphere of extremely small, dry particles which are invisible to the naked eye but are numerous enough to give the sky an appearance of opalescence. [14] |
| 1367 | Hulk | the hull of a wrecked or condemned ship, from which the fittings and superstructure have usually been removed, which is moored in a permanent position or grounded. [14] |
| 1368 | Int1 | the compendium of symbols, abbreviations and terms to be used on paper and raster nautical charts, for use principally as a reference by mariners, as derived from the "regulations of the IHO for international (int) charts and chart specifications of the IHO" (IHO s-4). [14] |
| 1369 | Lull | A momentary decrease in the speed of the wind. [14] |
| 1370 | Ooze | A soft mud or slime. A fine-grained pelagic sediment containing undissolved sand- or silt-sized, calcareous or siliceous skeletal remains of small marine organisms in proportion of 30 percent or more, the remainder being amorphous clay-sized material. [14] |
| 1371 | Snag | A tree or branch embedded in a river or lake bottom and not visible on the surface, forming thereby a hazard to boats. [14] |
| 1372 | Spit | A small point of land or narrow shoal projecting into a body of water from the shore. [14] |
| 1373 | Sway | The side-to-side bodily motion of a ship, independent of rolling, caused by uniform pressure being exerted all along one side of the hull. [14] |
| 1374 | Thaw | Melting of snow and/or ice, at the earth's surface, following a temperature rise above 0°c. [14] |
| 1375 | Trim | The way in which a ship floats on the water, in relation to her fore-and-aft line, whether on an even keel or down by the bow or by the stern. [14] |
| 1376 | Tufa | A chemical sedimentary rock composed of calcium carbonate or silica, precipitated from percolating ground water or from a spring. [14] |
| 1377 | Wadi | A watercourse that is permanently dry or dry except for the rainy season. [14] |
| 1378 | Wake | The path of disturbed water or air behind a craft in motion. [14] |
| 1379 | Watt | The unit of power in the si system. [14] |
| 1380 | Apron | 1. A gently dipping featureless surface, underlain primarily by sediment, at the base of any steeper slope. 2. The area of wharf or quay for handling cargo. 3. A sloping underwater extension of an iceberg. 4. An outwash plain along the front of a glacier. [14] |
| 1381 | Apsis | (pl. Apsides) see line of apsides. [14] |
| 1382 | Awips | Acronym for advanced weather interactive processing system. New computerized system that integrates and processes data received at a weather forecasting office from nexrad, asos, and analysis and guidance products prepared by nmc. [1] |
| 1383 | Barye | Pressure unit in the cgs system. [14] |
| 1384 | Bight | A bend or curve in the coastline, a bend in a river, etc. In ice terminology, an extensive crescent-shaped indentation in the ice edge formed either by wind or current. [14] |
| 1385 | Bluff | A cliff or headland with an almost perpendicular face. [14] |
| 1386 | Butte | An isolated flat-topped hill, similar to, but smaller than a mesa. [14] |
| 1387 | Cairn | A mound of stones, usually conical or pyramidal, raised as a landmark or to designate a point of importance in surveying. [14] |
| 1388 | Chaos | The property describing a system that exhibits erratic behavior in that very small changes in the initial state of the system rapidly lead to large and apparently unpredictable changes sometime in the future. [1] |
| 1389 | Crack | Any fracture or rift in sea ice not sufficiently wide to be described as a lead. [14] |
| 1390 | Creek | A comparatively narrow inlet, of fresh or salt water, which is tidal throughout its whole course. A small tributary. A small, narrow bay which extends farther inland than a cove. [14] |
| 1391 | Elbow | A sudden turn in a channel, river, or shoreline. [14] |
| 1392 | Farad | The unit of electrical capacitance, in the si system. [14] |
| 1393 | Firth | A Scottish word: an arm of the sea; an estuary of a river. [14] |
| 1394 | Fjord | See fiord. [14] |
| 1395 | Flume | An inclined channel for conveying water from a distance to be utilized for power, transportation, irrigation, etc. [14] |
| 1396 | Gamma | Photographic term for negative contrast resulting from development, and not the contrast of the subject itself; a numerical measure of contrast in the development of a negative. A small unit of magnetic field intensity generally used in describing the earth's magnetic field. It is defined as being equal to 10-5 oersted. [14] |
| 1397 | Gully | Small valley cut into soft sediments on the continental shelf or continental slope. [14] |
| 1398 | Henry | The unit of electrical inductance in the si system. [14] |
| 1399 | Knoll | A relatively small isolated elevation of a rounded shape. On the sea floor, an elevation somewhat smaller than a seamount and of rounded profile characteristically isolated or as a cluster. Also called hill. [14] |
| 1400 | Lough | Irish equivalent of the Scottish loch. [14] |
| 1401 | Lumen | The unit of luminous flux in the si system. [14] |
| 1402 | Lurch | A sudden roll to one side. See list. [14] |
| 1403 | Moire | Undesirable patterns occurring when reproductions are made from halftone proofs or steel engravings, caused by conflict between the ruling of the halftone screen and the dots or lines of the original; a similar pattern occurring in multicolor halftone reproductions and usually due either to incorrect screen angles or misregister of the colour impressions during printing. [14] |
| 1404 | Mouse | In computer systems, a pointing device operated by moving on a flat surface. See also cursor, joy-stick. [14] |
| 1405 | Shuga | An accumulation of spongy white ice lumps, a few centimeters across; the lumps are formed from grease ice or slush and sometimes from anchor ice rising to the surface. [14] |
| 1406 | Sleet | A type of precipitation consisting of transparent pellets of ice 5 mm or less in diameter. Same as ice pellets. [1] |
| 1407 | Slime | Soft, fine, oozy mud or other substance of similar consistency. [14] |
| 1408 | Squat | For a ship underway, the change of level of the bow and stern from the still water condition in re-sponse to the elevation and depression of the water level about the hull resulting from the bow and stern wave systems. [14] |
| 1409 | Talus | A slope. A sloping mass of detritus lying at the base of a cliff or the like, and consisting of material which has fallen from its face; also the slope or inclination of the surface of such a mass. [14] |
| 1410 | Tesla | The unit of magnetic flux density in the si system. [14] |
| 1411 | Varve | A sedimentary deposit, bed, or lamination deposited in one season. It is usually distinguished by colour or composition and used as an index to changes in the depositional environment. [14] |
| 1412 | Virga | Precipitation that falls from a cloud but evaporates before reaching the ground. (see fall streaks.) [1] |
| 1413 | Weber | The unit of magnetic flux in the si system. [14] |
| 1414 | Wedge | In optics, a refracting prism of very small deviation such as those used in the eyepiece of some stereoscopes. In meteorology, term synonymous with ridge, though usually applied to a fast-moving ridge between two depressions or troughs. [14] |
| 1415 | Billow | A great wave. [14] |
| 1416 | Boring | Forcing a vessel under power through ice. [14] |
| 1417 | Camber | A small basin, usually with a narrow entrance, situated inside a harbor. [14] |
| 1418 | Choppy | (adj). Of the sea, having short, abrupt, breaking waves dashing against each other. [14] |
| 1419 | Cobble | A naturally rounded stone larger than a pebble. [14] |
| 1420 | Corona | Photometeor formed by one or more sequences (seldom more than three) of coloured rings of relatively small radius, centered on the sun or moon. [14] |
| 1421 | Crater | Bowl-shaped cavity, at the summit or on the side of a volcano. [14] |
| 1422 | Cupola | A small dome-shaped tower or turret rising from a building. [14] |
| 1423 | Cutter | A boat belonging to a warship. [14] |
| 1424 | Dries' | see covers and uncovers. [14] |
| 1425 | Duplex | A method in which telecommunication between two stations can take place in both directions simultaneously. [14] |
| 1426 | Fading | Loss of strength in received signals due to temporary variations in the conditions of propagation. [14] |
| 1427 | Fender | A device let down between the side of a ship or a wharf or other ship to protect from chafing when ships are lying alongside or to take the shock of a bump when going alongside. [14] |
| 1428 | Haboob | A dust or sandstorm that forms as cold downdrafts from a thunderstorm turbulently lift dust and sand into the air. [1] |
| 1429 | Homing | Navigation toward a point by maintaining constant some navigational coordinate(s), usually bearing. The procedure of using the direction-finding equipment of one radio station with the emission of another radio station, where at least one of the stations is mobile, and whereby the mobile station proceeds continuously towards the other station. [14] |
| 1430 | Klaxon | A small power fog signal sometimes operated by hand. [14] |
| 1431 | League | A varying measure of distance, usually about three miles. [14] |
| 1432 | Leeway | The leeward motion of a vessel due to wind. It may be expressed as distance, speed, or angular difference between course steered and course through the water. Drift angle. Also called drift. [14] |
| 1433 | Lipper | Slight ruffling or roughness on a water surface. Light spray from small waves. Also called leaper. [14] |
| 1434 | Marina | A harbor facility for small boats, yachts, etc., where supplies, repairs, and various services are available. [14] |
| 1435 | Massif | A large mountain-mass; the central mass of a mountain; a compact and more or less independent portion of a range. [14] |
| 1436 | Newton | The unit of force in the si system. [14] |
| 1437 | Nipped | (Adj. And adv.). Said of a ship which is beset when ice forcibly presses against it. See beset, icebound. [14] |
| 1438 | Offing | That part of the visible sea a considerable distance from the shore, or that part just beyond the limits of the area in which a pilot is needed. [14] |
| 1439 | Photic | (Adj.). Of sea water, that is penetrated or influenced by sunlight. [14] |
| 1440 | Photon | A discrete quantity of energy that can be thought of as a packet of electromagnetic radiation traveling at the speed of light. [1] |
| 1441 | Polder | Land reclaimed from the sea or other body of water by the construction of an embankment to restrain the water. See dike. [14] |
| 1442 | Puddle | An accumulation on the ice of melt water, mainly due to melting snow, but in the more advanced stages also to the melting of ice. Initial stage consists of patches of melted snow. [14] |
| 1443 | Pulsar | A rotating neutron star emitting electromagnetic radiation in regular pulses related to its rotational period. [14] |
| 1444 | Pumice | An excessively cellular, glassy lava. It is very light and can float on water until it becomes waterlogged and sinks. [14] |
| 1445 | Q-Wave | See wave: love. [14] |
| 1446 | Radome | A dome, usually of glass reinforced plastic, housing a radar aerial. These domes are often prominent. The term is also used for domes or pods housing similar equipment in ships or on aircraft. [14] |
| 1447 | Ravine | In general, any steep-sided valley. [14] |
| 1448 | Refuge | A place of safety for a vessel in danger. [14] |
| 1449 | Reseau | A network. In photography, a glass plate on which is etched a network of fine lines. Sometimes used as a focal-plane plate to provide a means of calibrating film distortion. [14] |
| 1450 | Rodman | A person using a surveying rod. [14] |
| 1451 | Rotors | Turbulent eddies that form downwind of a mountain chain, creating hazardous flying conditions. [1] |
| 1452 | Rubble | Fragments of hard sea ice, roughly spherical and up to 1,5 meters (5 feet) in diameter, resulting from the disintegration of larger ice formations. When afloat, commonly called brash ice. Loose angular rock fragment. [14] |
| 1453 | Runnel | The smallest of natural streams; a brook or run. A trough or corrugation formed in the foreshore or in the bottom, immediately offshore, formed by waves or tidal currents. [14] |
| 1454 | Salina | A salt marsh or salt pond separated from the sea but flooded by high tides. [14] |
| 1455 | School | See shoal. [14] |
| 1456 | Slough | A minor marshland or tidal waterway which usually connects other tidal areas; often more or less equivalent to a bayou. Quagmire, swamp, miry place. [14] |
| 1457 | Sluice | Sliding gate or other contrivance for changing the level of a body of water by controlling flow into or out of it. [14] |
| 1458 | Steppe | An area of grass-covered, treeless plains that has a semiarid climate. [1] |
| 1459 | Strath | A broad elongated depression with relatively steep walls located on a continental shelf. The longi-tudinal profile of the floor is gently undulating with greatest depths often found in the inshore portion. [14] |
| 1460 | Stylus | A pointer that is operated by placing it in a display space or a tablet. [14] |
| 1461 | Sundog | A colored luminous spot produced by refraction of light through ice crystals that appears on either side of the sun. Also called parhelia. [1] |
| 1462 | Tie In | (v.i.). See tie. [14] |
| 1463 | Tongue | A projection of the ice edge up to several kilometers in length, caused by wind and current. A relatively narrow strip of land. An inlet. A narrow, rapid current. A protrusion of water into a region of different temperature. [14] |
| 1464 | Trivet | A low support for a surveying instrument which is used where a tripod cannot be used. [14] |
| 1465 | Typhon | A diaphragm horn which operates under the influence of compressed air or steam. Called siren in Canadian terminology. Also called Tyfon. [14] |
| 1466 | Varsol | An oil used as the liquid in some modern magnetic compasses. [14] |
| 1467 | Veneer | A thin layer of sediment covering a rocky surface. [14] |
| 1468 | Vertex | (pl. Vertices). The highest point; the vertices of a great circle are the points nearest the pole. See apex. [14] |
| 1469 | Aphotic | (Adj.). Without light. [14] |
| 1470 | Blow Up | Enlarge photographically. [14] |
| 1471 | Boulder | A rounded rock with a diameter of 256 millimeters (about 10 inches) or larger. [14] |
| 1472 | Calving | The breaking away of a mass of ice from a glacier, ice front, or iceberg. [14] |
| 1473 | Clutter | Confused unwanted echoes on a radar display. [14] |
| 1474 | Console | The housing of the main operating unit of electronic equipment, in which indicators and general controls are located. A portion of a computer used to control the machine manually. [14] |
| 1475 | Coulomb | The unit of electric charge in the si system. [14] |
| 1476 | Damping | The dissipation of energy with time or distance. The progressive reduction of amplitude of oscillations, waves, etc. [14] |
| 1477 | Decibar | One-tenth of a bar. [14] |
| 1478 | Decibel | See bel. [14] |
| 1479 | Derecho | Strong, damaging, straight-line winds associated with a cluster of severe thunderstorms that most often form in the evening or at night. [1] |
| 1480 | Derrick | A tall pyramid of latticed steel mounted over a borehole. [14] |
| 1481 | Diopter | A unit of refractive power of an optical system in the si system. [14] |
| 1482 | Dog Leg | A leg which does not lead directly to the destination or way point. [14] |
| 1483 | Dredger | A vessel or floating structure equipped with machinery for excavating ditches or canals, deepening channels and harbors, and removing solid matter from the bottom of a water area. Also called a dredge. [14] |
| 1484 | End Lap | See overlap. [14] |
| 1485 | Fog Gun | A gun used as a fog signal. [14] |
| 1486 | Freshet | An area of comparatively fresh water at or near the mouth of a stream flowing into the sea. A flood or overflowing of a river caused by heavy rains or melted snow. [14] |
| 1487 | Glitter | The spots of light reflected from a point source by the surface of the sea. [14] |
| 1488 | Granite | Light-coloured, acidic igneous rock mineralogically composed primarily of quartz and potassium-sodium rich feldspars in which the mineral grains are visible to the naked eye (phaneritic texture). [14] |
| 1489 | Growler | A piece of ice almost awash, smaller than a bergy bit. [14] |
| 1490 | Holiday | An unintentional unsurveyed area within a given hydrographic survey where the spacing between sounding lines or surveys exceeds the maximum allowable limits. [14] |
| 1491 | Hunting | Fluctuation about a midpoint due to instability, as oscillations of the needle of an instrument about the zero point, or alternate lead and lag of a synchronous motor with respect to the alternating current. [14] |
| 1492 | Indelta | Inland area where a river subdivides (now in common use, especially in Australia). [14] |
| 1493 | Isogriv | A line connecting points of equal grid variation. [14] |
| 1494 | Isotope | Two or more nuclides having the same atomic number, hence constituting the same element, but differing in mass number. [14] |
| 1495 | Isthmus | A narrow strip of land connecting two larger bodies of land. [14] |
| 1496 | Kedging | Moving a vessel by laying out an anchor and then hauling the vessel up to the anchor. [14] |
| 1497 | La Niña | A condition where the central and eastern tropical pacific ocean turns cooler than normal. [1] |
| 1498 | Locking | In electronic navigation, a term describing the condition of two transmitters when their signals maintain a stable phase relationship. One station is then said to be locked to the other. [14] |
| 1499 | Logging | 1. Gauging ship's speed with a log. 2. Record events. [14] |
| 1500 | Lowland | Low and relatively level land at a lower elevation than adjoining districts. [14] |
| 1501 | Magenta | Adj.). A mixture of red and blue in equal parts. [14] |
| 1502 | Meander | (often in plural). A winding, convolution or winding course, as of a stream. A deviation of the flow pattern of a current. [14] |
| 1503 | Mock-Up | A model of something to be used for testing or study. [14] |
| 1504 | Monsoon | Wind of the general circulation of the atmosphere, typified by the seasonal persistence of a given wind direction and by a pronounced change in this direction from one season to another. The term is generally confined to those cases in which the primary cause is the differential heating (changing in nature from summer to winter) of a continent relative to a neighbouring ocean. [14] |
| 1505 | Montage | A series of related pieces of copy appearing as one to tell a complete story. [14] |
| 1506 | Narrows | A navigable narrow part of a bay, strait, river, etc. [14] |
| 1507 | Nipping | The closing of ice around a ship so that the ship is beset and subjected to pressure from the ice. [14] |
| 1508 | Nodules | In oceanography, concretionary lumps of manganese, cobalt, iron, and nickel found widely scattered on the ocean floor. Rocks of various sizes and shapes often are encrusted with these metals. [14] |
| 1509 | Nowcast | Short-term weather forecasts varying from minutes up to a few hours. [1] |
| 1510 | Nunatak | An isolated hill or mountain peak of rock projecting above an inland ice sheet. [14] |
| 1511 | Oersted | The cgs unit of magnetic field intensity in the si system. [14] |
| 1512 | Old Ice | Any sea ice more than 1 year old. [14] |
| 1513 | Outcrop | Naturally protruding, or erosional exposed or uncovered part of a rock, most of which is covered by overlying material. [14] |
| 1514 | Pontoon | Floating structure, usually rectangular in shape which serves as landing, pierhead or bridge support. [14] |
| 1515 | Pricker | A pointed tool used instead of a pencil for laying off finer and more accurate lines on a plotting sheet. [14] |
| 1516 | Quayage | A comprehensive term embracing all the structures in a port alongside which vessels can lie. [14] |
| 1517 | Rainbow | Groups of concentric arcs with colors ranging from violet to red, produced on a "screen" of water drops (raindrops, droplets of drizzle or fog) in the atmosphere by light from the sun or moon. [14] |
| 1518 | Red Mud | See mud. [14] |
| 1519 | Rivulet | A small river. [14] |
| 1520 | Road(S) | See roadstead. [14] |
| 1521 | Sanding | An irregular dot pattern used on some of the early hydrographic surveys to accentuate the area between the high- and low-water lines. [14] |
| 1522 | Savanna | A tropical or subtropical region of grassland and drought-resistant vegetation. Typically found in tropical wet- and-dry climates. [1] |
| 1523 | Sea Fog | See fog. [14] |
| 1524 | Seamark | An aid to navigation located with the express purpose of being visible from a distance to seaward. Often erected in shoal water rather than on land. [14] |
| 1525 | Seaport | A port on or near the sea and readily accessible to seagoing vessels. [14] |
| 1526 | Shimmer | Apparent fluttering of objects at the earth's surface, when they are viewed in an almost horizontal direction above strongly heated surfaces. [14] |
| 1527 | Shingle | Rounded, often flat waterworn rock fragments larger than approximately 16 millimeters. [14] |
| 1528 | Siemens | The unit of conductance in the si system. [14] |
| 1529 | Sigma-T | Symbol ïƒ t). A conveniently abbreviated value of the density of a sea water sample of temperature t and salinity s: ïƒt = (rho(s,t)-1) * 1000 , where rho(s,t) is the value of the sea water density in cgs units at standard atmospheric pressure. If, for example, rho(s,t) = 1.02648, then ïƒt = 26.48. [14] |
| 1530 | Simplex | A method in which telecommunication between two stations takes place in one direction at a time. [14] |
| 1531 | Sparker | An echo sounder which uses an electrical spark discharge as the sound source. A recorder produces a chart which represents a vertical cross section of the geological structure beneath the water bottom. [14] |
| 1532 | Spindle | A spar serving as a beacon. A slender pin or rod, as one constituting part of a machine. [14] |
| 1533 | Splines | Flexible rulers or interpolation algorithm used to draw smooth curves between points when constructing e.g. Hyperbolic lattices. [14] |
| 1534 | Stratum | (pl. Strata). A single sedimentary bed or layer of generally homogenous rock, independent of thickness. [14] |
| 1535 | Subplan | An inset on a survey sheet used to extend the survey coverage shown on the sheet, or to show small congested areas at enlarged scales. [14] |
| 1536 | Sundial | An instrument that indicates time by the position of the shadow of a pointer or gnomon cast by the sun on the face of a dial marked in hours. [14] |
| 1537 | Syntony | The situation of two or more oscillating circuits having the same resonant frequency. [14] |
| 1538 | Thalweg | See talweg. [14] |
| 1539 | Tideway | A channel through which a tidal current runs. [14] |
| 1540 | Tillite | Rock formed of consolidated or lithified till and generally a record of a glacial epoch, older than that of the quaternary. [14] |
| 1541 | Tonnage | The carrying capacity of ships. [14] |
| 1542 | Tripton | Collectively, all of the dead suspended particulate matter in aquatic habitats. [14] |
| 1543 | Viaduct | A structure consisting of a series of arches or towers supporting a roadway, waterway, etc., across a depression, etc. [14] |
| 1544 | Westing | The distance a craft makes good to the west. The opposite is easting. [14] |
| 1545 | Wet Fog | See fog. [14] |
| 1546 | Y-Level | See levelling instrument: y level. [14] |
| 1547 | Aerology | Study of the free atmosphere. [14] |
| 1548 | Aerovane | A wind instrument that indicates or records both wind speed and wind direction. Also called a skyvane. [1] |
| 1549 | Affluent | A stream flowing into a larger stream or lake; a tributary. [14] |
| 1550 | Analemma | A scale of the sun's daily declination drawn from tropic of cancer to tropic of Capricorn on terrestrial globes. An orthographical projection of the sphere made on the plane of the meridian, the eye being supposed to be an infinite distance and in the east or west point of the horizon. [14] |
| 1551 | Array(S) | The order in which equipment (antenna, oceanographic equipment) or mathematical quantities are ordered. [14] |
| 1552 | Avulsion | Rapid erosion of shoreland by waves during a storm. [14] |
| 1553 | Backwash | Water or waves thrown back by an obstruction such as a ship, breakwater, cliff, etc. [14] |
| 1554 | Bar Buoy | A buoy marking the location of a bar. [14] |
| 1555 | Barogram | Record made by a barograph. [14] |
| 1556 | Base Map | See map. [14] |
| 1557 | Beam Sea | Waves moving in a direction approximately 90° from the heading. [14] |
| 1558 | Blizzard | Violent and very cold wind which is laden with snow, some part, at least, of which has been raised from snow-covered ground. This term originated in north America but has been extended to include similar winds in other countries. [14] |
| 1559 | C/A Code | The standard (coarse/acquisition, or clear/access) gps code; a sequence of 1023 pseudo-random binary biphase modulations on the gps carrier at a chip rate of 1.023 MHz, thus having a code repetition period of one millisecond. See also p-code. [14] |
| 1560 | Cadastre | A public record of the extent, value, and ownership of land for purposes of taxation. [14] |
| 1561 | Causeway | A raised way across low or wet ground or water. [14] |
| 1562 | Chaining | See taping. [14] |
| 1563 | Clapotis | The french equivalent for a type of standing wave. [14] |
| 1564 | Co-Phase | see. CO-TIDAL [14] |
| 1565 | Co-Range | Lines on a cotidal chart joining places which have the same tidal range or amplitude. Usually drawn for a particular constituent or tidal condition (e.g. spring tides). [16] |
| 1566 | Co-Tidal | Lines on a cotidal chart joining places where tide has the same phase, for example where high water occurs at the same time. Usually drawn for a particular constituent or tidal condition. [16] |
| 1567 | Data Set | A logical entity of data consisting of several elements (fields) grouped under one criterion. [14] |
| 1568 | Deadbeat | (Adj.). Aperiodic, or without a period. [14] |
| 1569 | Deadhead | (1) a block of wood used as anchor buoy. (2) a bollard. [14] |
| 1570 | Diaphone | A device operated by compressed air for producing a distinctive fog signal. [14] |
| 1571 | Doldrums | The region near the equator that is characterized by low pressure and light, shifting winds. [1] |
| 1572 | Doldrums | Zone of calm or light variable winds, in the lower atmospheric layers, situated near the thermal equator; the zone follows, with slight time lag, the annual meridional fluctuation of the thermal equator. [14] |
| 1573 | Duplexer | A switching device used to connect a transmitter and a receiver to the same antenna. [14] |
| 1574 | Fog Bank | Fog, generally caused by local conditions, which extends over a small area some hundreds of meters wide. [14] |
| 1575 | Fog Bell | A bell used as a fog signal. [14] |
| 1576 | Fog Gong | A gong used as a fog signal. [14] |
| 1577 | Fog Horn | A horn used as a fog signal. [14] |
| 1578 | Fog: Ice | Suspension of numerous minute ice crystals in the air, reducing the visibility at the earth's surface. [14] |
| 1579 | Fog: Sea | Advection fog which forms over the sea. [14] |
| 1580 | Fog: Wet | Fog formed of droplets sufficiently large to deposit water on objects. [14] |
| 1581 | Foreland | A cape or promontory. [14] |
| 1582 | Gram(Me) | A cgs unit of mass equal to one one-thousandth of a kilogram. [14] |
| 1583 | Halation | In photography, a spreading of a photographic image beyond its proper boundaries, due especially to reflection from the side of the film or plate support opposite to that on which the emulsion is coated. Particularly noticeable in photographs of bright objects against a darker background. [14] |
| 1584 | Halftone | In photography or printing, a technique in which the solid image is broken up by the use of a screen into evenly spaced dots of equal density but of varying size. This gives an illusion of continuous tone. [14] |
| 1585 | Hatching | The drawing or engraving of fine, parallel or crossed lines to show shading. [14] |
| 1586 | Head Sea | A sea in which the waves move in a direction approximately opposite to the heading. [14] |
| 1587 | Heli Pad | A site on which helicopters may land and take off. [14] |
| 1588 | Ice Free | Water surface completely free of ice. [14] |
| 1589 | Isobront | Line joining, on a chart, places on the earth's surface where, on a given day, the first clap of thunder has been heard simultaneously. In climatology, line drawn on a chart through places which have the same average number of days on which thunder is heard in a given period. [14] |
| 1590 | Isostasy | A condition of approximate equilibrium in the outer part of the earth, such that the gravitational effect of masses extending above the surface of the geoid in continental areas is approximately counterbalanced by a deficiency of density in the material beneath those masses while the effect of deficiency of density in the ocean waters is counterbalanced by an excess of density in the material under the oceans. [14] |
| 1591 | Joystick | In computer systems, a pointing device operated by pressing a stick in a desired direction. [14] |
| 1592 | Keg Buoy | A buoy consisting of a keg to which is attached a small pole with a flag, used by fishermen to mark the position of a trawl line. See dan buoy. [14] |
| 1593 | Lake Ice | Ice formed in lakes. [14] |
| 1594 | Laterite | A soil formed under tropical conditions where heavy rainfall leaches soluble minerals from the soil. This leaching leaves the soil hard and poor for growing crops. [1] |
| 1595 | Lee Tide | See tide: leeward. [14] |
| 1596 | Level: Y | See levelling instrument: y level. [14] |
| 1597 | Littoral | (Adj.). Of or pertaining to a shore, especially of the sea. [14] |
| 1598 | Littoral | (n.). A coastal region. Intertidal zone. [14] |
| 1599 | Log Book | Book in which events connected with the ship are entered. Also written as one word. [14] |
| 1600 | Log Boom | Heavy logs chained or lashed together and moored or anchored so as to enclose and contain rafted logs. See also boom. [14] |
| 1601 | Log Ship | See log chip. Also written as one word. [14] |
| 1602 | Make Way | To progress through the water. [14] |
| 1603 | Milligal | A unit of acceleration equal to 1/1,000 of a gal, or 1/1,000 centimeter per second, per second. This unit is used in gravity measurement, being approximately one-millionth of the average gravity at the earth's surface. [14] |
| 1604 | Mud: Red | A reddish-brown terrigenous deep-sea mud which accumulates on the sea floor in the neighbour-hood of deserts and off the mouths of great rivers; contains calcium carbonate up to 25 per cent. [14] |
| 1605 | Nun Buoy | A buoy the above water part of which is in the shape of a cone or a truncated cone. [14] |
| 1606 | Parabola | An open curve all points of which are equidistant from a fixed point, called the focus, and a straight line. [14] |
| 1607 | Pictomap | A map supplement on which the photographic imagery of a standard photomosaic has been con-verted into interpretable colors and symbols by means of tonal masking techniques. [14] |
| 1608 | Pierhead | The outer end of a pier. Also called wharfhead. [14] |
| 1609 | Pinpoint | (v.t. And i.). To establish (position) with great accuracy. [14] |
| 1610 | Pitching | See pitch. [14] |
| 1611 | Planform | The outline or shape of a body of water as determined by the still water level. [14] |
| 1612 | Porosity | The ratio of the aggregate volume of pore space in a rock or sediment to its total volume, usually expressed as a percentage. [14] |
| 1613 | Psephyte | A coarse fragmental rock (conglomerate) or deposit composed of rounded pebbles. [14] |
| 1614 | Q-Factor | The pressure coefficient of the unprotected thermometer expressed in °c. [14] |
| 1615 | Quintant | A double-reflecting instrument for measuring angles. It is similar to a sextant, but has an arc of 72°. [14] |
| 1616 | Rapid(S) | Portions of a stream with accelerated current where it descends rapidly but without a break in the slope of the bed sufficient to form a waterfall. Usually used in the plural. [14] |
| 1617 | Repromat | Reproduction material, generally in the form of positive or negative copies on film or glass for each colour plate, from which a map or chart may be reproduced without redrafting. [14] |
| 1618 | Rockweed | One of a group of marine plants, principally of an order (fucales) of the brown algae, mostly multi-branched and leathery, which grow attached to rocks in the intertidal zone by means of an organ called a holdfast. Also called wrack or fucus. [14] |
| 1619 | Sandwave | a large wavelike sediment feature in very shallow water and composed of sand. The wavelength may reach 100 meters; the amplitude may be up to 20 meters. Also sand-wave or sand wave. Sometimes called a mega-ripple. [14] |
| 1620 | Sea Moat | See moat. [14] |
| 1621 | Seashore | The shore of a sea or ocean. [14] |
| 1622 | Shelving | A gently sloping area. [14] |
| 1623 | Shipyard | A place where ships are built or repaired. [14] |
| 1624 | Side Lap | See overlap. [14] |
| 1625 | Solenoid | A coil of wire, often helical in form, which becomes an electromagnet when an electric current is passed through it. [14] |
| 1626 | Southing | The distance a craft makes good to the south. The opposite is northing. [14] |
| 1627 | Steep-To | (Adj.). Precipitous. The term is applied particularly to a shore, bank or shoal that descends steeply to a lower level. [14] |
| 1628 | Sternway | Making way through the water in a direction opposite to the heading. [14] |
| 1629 | Stooping | Apparent decrease in the vertical dimension of an object near the horizon, due to large inequality of atmospheric refraction in the line of sight to the top and bottom of the object. The opposite is towe-ring. [14] |
| 1630 | Subsonic | (Adj.). Designating or of speeds that are less than that of sound. [14] |
| 1631 | Swashway | See swash. [14] |
| 1632 | Tidemark | A high water mark left by tidal water. The highest point reached by a high tide. A mark placed to indicate the highest point reached by a high tide, or, occasionally, any specified state of tide. [14] |
| 1633 | Toponymy | The place names or the study of place names of a country or district. [14] |
| 1634 | Towering | Apparent increase in the vertical dimension of an object near the horizon, due to large inequality of atmospheric refraction in the line of sight to the top and bottom of the object. The opposite is stoo-ping. [14] |
| 1635 | Undertow | A seaward flow near the bottom of a sloping beach. The subsurface return by gravity flow of the water carried up on shore by waves or breakers. See also backrush. [14] |
| 1636 | Wave Age | The state of development of a wind-generated sea surface wave, conveniently expressed by the ratio of wave speed to wind speed. Wind speed is usually measured at about 8 meters above still water level. [14] |
| 1637 | Wet Dock | See dock. [14] |
| 1638 | Whitecap | A crest of a wave which becomes unstable in deep water, toppling over or breaking. See breaking of waves. [14] |
| 1639 | Wireless | See radio. [14] |
| 1640 | Advection | The horizontal transfer of any atmospheric property by the wind. [1] |
| 1641 | Altimetry | The process of determining the difference of elevation by the use of altimeters. [14] |
| 1642 | Ambiguity | Uncertainty of value or meaning because of the possibility of two or more interpretations. The condition when navigational coordinates define more than one position, direction, line of position, or surface of position. [14] |
| 1643 | Amidships | At, near, or toward the middle of a ship. [14] |
| 1644 | Anemogram | Record of the anemograph. [14] |
| 1645 | Angstroem | A unit of length, used especially in expressing the length of light waves, equal to one ten-thousandth of a micron or one hundred-millionth of a centimeter (1 x 10-8 cm). [14] |
| 1646 | Anticline | An arch of stratified rock in which the layers bend downward in opposite directions from the crest. [14] |
| 1647 | Backshore | That part of a beach which is usually dry, being reached only by the highest tides. Also called back beach. See also foreshore. [14] |
| 1648 | Backwater | Water turned back by an obstruction, opposing current, etc. Water held back from the main flow. [14] |
| 1649 | Bandwidth | The number of units (hertz, kilohertz, etc.) Of frequency required for transmission. [14] |
| 1650 | Bar Check | An on-site calibration method for echo sounders. [14] |
| 1651 | Barograph | Recording barometer. [14] |
| 1652 | Barotropy | The condition and type of motion in which pressure is constant on surfaces of constant density, e.g. Surface tides. [14] |
| 1653 | Base Tilt | See tilt. [14] |
| 1654 | Beaconage | A system of beacons. See buoyage. [14] |
| 1655 | Beam Wind | Wind blowing in a direction approximately 90° from the heading. [14] |
| 1656 | Bell Buoy | See buoy: sound. [14] |
| 1657 | Bergy Bit | A massive piece of sea ice or disrupted hummocked ice; also medium-sized piece of floating glacier ice. Generally less than 5 m above sea level, and not more than about 10 m across. [14] |
| 1658 | Berm Line | In cartography, the outer edge of vegetation shown as shoreline on charts in marsh or mangrove areas. [14] |
| 1659 | Biosphere | Spherical terrestrial layer comprising the lower part of the atmosphere, the seas and the upper layers of the soil within which living organisms can exist naturally. [14] |
| 1660 | Black Ice | A thin sheet of ice that appears relatively dark and may form as supercooled droplets, drizzle, or light rain come in contact with a road surface that is below freezing. Also, thin dark-appearing ice that forms on freshwater or saltwater ponds, or lakes. [1] |
| 1661 | Boat Grid | See careening grid or gridiron. [14] |
| 1662 | Boat Slip | A slipway designed specifically for boats. [14] |
| 1663 | Brash Ice | Accumulation of floating ice made up of small fragments not more than 2 meters across; the wreckage of other forms of ice. [14] |
| 1664 | Cartogram | A map showing geographical statistics by means of lines, dots, shaded areas, etc. [14] |
| 1665 | Cartouche | A panel on a map, often with decoration, enclosing the title or other legends, the scale, etc. [14] |
| 1666 | Cold Wave | Marked cooling of the air, or the invasion of very cold air, over a large area. [14] |
| 1667 | Collimate | (v.t.). In physics and astronomy, to render parallel to a certain line or direction; to render parallel, as rays of light; to adjust the line of sight of an optical instrument so that it is in the proper position relative to the other parts of the instruments. In photogrammetry, to adjust the fiducial marks of a camera so that they define the principal point. [14] |
| 1668 | Condenser | In optics, a lens or lens system designed to concentrate the illumination from a light source on a limited area. In electricity, a device for receiving and storing an electric charge. Also called a capacitor. [14] |
| 1669 | Cross Sea | A series of waves or swell crossing another wave system at an angle. [14] |
| 1670 | Ctd Probe | Instrument for measuring electrical conductivity, temperature and depth of the sea water. See probe. [14] |
| 1671 | Deflector | An instrument for measuring the directive force acting on a magnetic compass on different headings, for use in compass adjustment. [14] |
| 1672 | Depressor | A device to maintain a towfish at a given depth. [14] |
| 1673 | Detail(S) | In cartography, the items or particulars of information (shown on a map by lines, symbols, and lettering) which, when considered as a whole, furnish the comprehensive representation of the physical and cultural features of the earth's surface. [14] |
| 1674 | Dew-Point | The temperature to which air must be cooled at constant pressure and constant water vapor content to reach saturation. [14] |
| 1675 | Digitizer | A computer aided device equipped with a digitizing table and a cursor for digitally capturing graphical data (pictures, charts), usually based on vector-techniques (as opposed to a scanner). The digitizing table consists of a gridded electrical network under the table's surface which allows an automatic computation of the planar x/y coordinates of a cursor's position. Lines are sequentially scanned by moving the cursor along the position and identifying the appropriate symbol on a menu. [14] |
| 1676 | Dock Sill | The foundation at the bottom of the entrance to a dry dock or lock against which the caisson or gates close. The depth of water controlling the use of the dock or lock is measured from the sill to the surface. [14] |
| 1677 | Dock: Wet | A dock in which water can be maintained at any level by closing a gate when the water is at the desired level. [14] |
| 1678 | Dry Proof | An impression of a chart pulled from the engraved plate onto a dry sheet of paper. This impression is fainter than a damp-pulled copy and unsuitable for ordinary use but is free from distortion. [14] |
| 1679 | Duststorm | Ensemble of particles of dust or sand energetically lifted to great heights by a strong and turbulent wind. Also called sandstorm. Also written as two words. [14] |
| 1680 | Dynameter | An instrument for measuring the magnifying power of a telescope. [14] |
| 1681 | Edge Wave | See wave. [14] |
| 1682 | Embayment | An indentation in a shoreline forming an open bay. [14] |
| 1683 | Extrusion | In cartography, the extension of detail outside the neat line. [14] |
| 1684 | Filtering | The process of selecting specific data from a specific source in accordance with certain rules, formulae, or algorithms. [14] |
| 1685 | Fish Lead | See lead. [14] |
| 1686 | Fish Weir | See fish trap. [14] |
| 1687 | Float-Off | (British terminology). The paper of a field board when detached from the board on completion of the work for which the field board was prepared. [14] |
| 1688 | Foam Line | The front of a wave as it advances shoreward, after it has broken. [14] |
| 1689 | Fog Siren | A siren used as a fog signal. [14] |
| 1690 | Foul Area | An area of numerous uncharted dangers to navigation. The area charted serves as a warning to the mariner that all dangers are not charted individually and that navigation through the area may be hazardous. The term "foul" should not be applied to a soft continuum with indefinite boundaries such as mud or sand; to areas congested with marine vegetation such as kelp or grass in water; or to materials not likely to cause damage to a vessel. [14] |
| 1691 | Free Port | A port where certain import and export duties are waived (unless goods pass into the country) to facilitate re-shipment to other countries. [14] |
| 1692 | Frostbite | The partial freezing of exposed parts of the body, causing injury to the skin and sometimes to deeper tissues. [1] |
| 1693 | Gamma Ray | See x-rays. [14] |
| 1694 | Gelbstoff | Yellowish organic material suspended in sea water which causes greenish colour of the sea water in coastal areas; usually transported into the sea by rivers. [14] |
| 1695 | Geomatics | The science and technology of spatial information management, including the acquisition, storage, analysis and processing, display and dissemination of geo-referenced information. [14] |
| 1696 | Geosphere | The solid and liquid portions of the earth; the lithosphere plus the hydrosphere. [14] |
| 1697 | Gong Buoy | See buoy: sound. [14] |
| 1698 | Half Byte | 4 bits of a 8 bit byte; usually used to encode the figures 0....9. [14] |
| 1699 | Halocline | A vertical gradient of salinity (which is usually positive) in some layer of the body of water, which is appreciably greater than the gradients above and below it. [14] |
| 1700 | Head Wind | Wind which blows in a direction opposite to that in which an object is moving, with respect to the earth's surface. [14] |
| 1701 | Heat Wave | Marked warming of the air, or the invasion of very warm air, over a large area. [14] |
| 1702 | Hodometer | See odometer. [14] |
| 1703 | Hook Echo | The shape of a hook on a doppler radar screen that indicates the possible presence of a tornado. [1] |
| 1704 | Horn Buoy | See buoy: sound. [14] |
| 1705 | Ice Blink | A typical whitish glare on low clouds above an accumulation of distant ice. It is especially glowing when observed on the horizon. [14] |
| 1706 | Ice Field | Area of pack ice consisting of any size floes, which is greater than 10 km across. [14] |
| 1707 | Ice Limit | The average position of the ice edge in any given month or period based on observations over a number of years. [14] |
| 1708 | Ice Storm | Intense formation of ice on objects by the freezing, on impact, of drops of rain or drizzle. [14] |
| 1709 | Impedance | The total opposition offered to an alternating current. It may consist of any combination of resistance, inductive reactance, or capacitive reactance. [14] |
| 1710 | Index Bar | See index arm. [14] |
| 1711 | Index Map | See map. [14] |
| 1712 | Ironbound | (Adj.). Said of a rugged, rocky coast which affords no anchorage. [14] |
| 1713 | Isoradial | A radial from the isocenter. [14] |
| 1714 | Leap Year | See year: civil. [14] |
| 1715 | Left Bank | Of a river, the bank of the left-hand side as one proceeds downstream. [14] |
| 1716 | Life Buoy | See buoy. [14] |
| 1717 | Lithology | The scientific study of rocks. Literally, the science of stones. [14] |
| 1718 | Localizer | A radio facility which provides signals for lateral guidance of aircraft with respect to a runway center line. [14] |
| 1719 | Log: Chip | A log consisting essentially of a weighted wooden quadrant attached to a bridle in such a manner that it will float in a vertical position, and a log line, speed being measured by casting the quadrant overboard and counting the knots in the line paid out in unit time. [14] |
| 1720 | L-Z Graph | A graph used to determine 'in situ' depths of oceanographic observations by the wire depths minus thermometric depth method. [14] |
| 1721 | Madrepore | A branching or stag-horn coral, also any perforated stone coral. [14] |
| 1722 | Magnetron | An electron tube for converting direct-current energy into radio-frequency energy by means of a magnetic field. [14] |
| 1723 | Manoeuvre | Planned and controlled movement of a vehicle. [14] |
| 1724 | Manometer | An instrument for measuring pressure of gases and vapors. [14] |
| 1725 | Map Nadir | See nadir. [14] |
| 1726 | Map Scale | See scale. [14] |
| 1727 | Map: Base | A map showing certain fundamental information, used as a base upon which additional data of specialized nature are compiled. Also, a map containing all the information from which maps showing specialized information can be prepared; a source map. [14] |
| 1728 | Marigraph | A recording tide gauge. [14] |
| 1729 | Mark Boat | A temporary sounding mark consisting of a whaler moored head and stern, with a signal on board. [14] |
| 1730 | Mean Noon | See noon. [14] |
| 1731 | Megacycle | One million cycles; one thousand kilocycles. The term is often used incorrectly as the equivalent of one million cycles per second. [14] |
| 1732 | Mesoscale | The scale of meteorological phenomena that range in size from a few km to about 100 km. It includes local winds, thunderstorms, and tornadoes. [1] |
| 1733 | Meteogram | A chart that shows how one or more weather variables has changed at a station over a given period of time or how the variables are likely to change with time. [1] |
| 1734 | Meteorite | A meteor that reaches the surface of the earth as a solid particle. [14] |
| 1735 | Metrology | The science of weights and measures. [14] |
| 1736 | Mock Suns | Name often given to parhelia, paranthelia and anthelia when they are particularly bright. [14] |
| 1737 | Multiplex | In photogrammetry, an instrument for making a topographic map from aerial photographs. A three-dimensional optical model of the terrain to be mapped is produced, in miniature, by direct optical projection from a pair of overlapping photographs. This instrument uses the anaglyph principle. [14] |
| 1738 | New Chart | See chart. [14] |
| 1739 | Open Port | A port which is not icebound during winter. [14] |
| 1740 | Open Wave | The stage of development of a wave cyclone (midlatitude cyclonic storm) where a cold front and a warm front exist, but no occluded front. The center of lowest pressure in the wave is located at the junction of the two fronts. [1] |
| 1741 | Orography | The branch of physical geography which deals with the formation and features of mountains; the description of mountains. [14] |
| 1742 | Overfalls | Short, breaking waves occurring when a strong current passes over a shoal or other submarine obstruction or meets a contrary current or wind. See rips. [14] |
| 1743 | Overprint | In cartography, an additional plate, generally in a distinctive colour, printed down on a map or chart which is already complete in itself. Overprints may be used to reproduce specialized information (e.g., to add aeronautical information to a topographic map) or to incorporate revision data without the amendment of existing plates. [14] |
| 1744 | Pie Graph | Circular symbol divided into sectors to indicate proportions of a total value. [14] |
| 1745 | Plumb Bob | A conical device, usually of brass and suspended by a cord, by means of which a point can be projec-ted vertically into space over relative short distances. Also referred to as plummet. [14] |
| 1746 | Quadripod | A four-legged stand for triangulation, signals, etc. [14] |
| 1747 | Quenching | The great reduction in underwater sound transmission or reception resulting from absorption and scattering of sound energy by air bubbles entrapped around the sonar dome. See attenuation. [14] |
| 1748 | Quicksand | A loose mixture of sand and water that yields to the pressure of heavy objects. Such objects are difficult to extract once they begin sinking. [14] |
| 1749 | Reed Horn | A horn that produces sound by means of a steel reed vibrated by air under pressure. [14] |
| 1750 | Rill Mark | A small groove, furrow or channel made in mud or sand on a beach by tiny streams following an outflowing tide. [14] |
| 1751 | Safetynet | The international service for the broadcast and automatic reception of maritime safety information via the inmarsat egc system in waters where an international navtex service is not provided. [14] |
| 1752 | Salt Pans | Shallow pools of brackish water used for the natural evaporation of sea water to obtain salt. [14] |
| 1753 | Sand Dune | A ridge of sand piled up by the action of wind on sea coasts or in deserts. [14] |
| 1754 | Sea Scarp | See escarpment. [14] |
| 1755 | Semaphore | Any apparatus for signaling. [14] |
| 1756 | Shoreface | The narrow zone seaward from the low tide shoreline, permanently covered by water, over which the beach sands and gravels actively oscillate with changing wave conditions. [14] |
| 1757 | Siltation | The deposition or accumulation of silt that is suspended in a body of water. [14] |
| 1758 | Smoothing | Averaging of data in space or time, designed to compensate for random errors or fluctuations of a scale smaller than that presumed significant to a specific problem. [14] |
| 1759 | Sonargram | The analog echo record produced by the side scan sonar recording device on special chemically-treated paper. [14] |
| 1760 | Sono-Buoy | A buoy with equipment for automatically transmitting a radio signal when triggered by an underwater sound signal. [14] |
| 1761 | Spar Buoy | A buoy made of a tapered log or metal shaped like a tapered log, and secured so as to float in an approximately vertical position. [14] |
| 1762 | Split Fix | See fix. [14] |
| 1763 | Standpipe | A tall cylindrical structure in a waterworks system, whose height is several times greater than its diameter. It extends from the ground and may be supported by a skeleton-type framework. [14] |
| 1764 | Steradian | The unit of a solid angle in the si system. [14] |
| 1765 | Stippling | Graduation of shading by numerous separate touches. Shallow areas on charts, for instance, are sometimes indicated by numerous dots decreasing in density as the depth increases. [14] |
| 1766 | Sun: Mean | A fictitious sun conceived to move eastward along the celestial equator at a rate that provides a uniform measure of time equal to the average apparent time. It is used as a reference for reckoning mean time, zone time, etc. [14] |
| 1767 | Sun: True | See sun: apparent. [14] |
| 1768 | Tableland | An elevated region of land with a generally level surface of large or considerable extent; a lofty plain; a plateau. [14] |
| 1769 | Tail Wind | Wind which blows in the same direction as that in which an object is moving, with respect to the earth's surface. [14] |
| 1770 | Tectonics | The study of origin and development of the broad structural features of the earth. [14] |
| 1771 | Telemetry | The study and technique involved in measuring a quantity or quantities in place, transmitting this value to a station, and there interpreting, indicating, or recording the quantities; and transmitting commands from the station to control the measurement device. [14] |
| 1772 | Telemotor | A hydraulic or electrical device controlling the action of power at a distance, specifically, a device which controls the steering gear of a ship. [14] |
| 1773 | Tide Gate | A restricted passage through which water runs with great speed due to tidal action. [14] |
| 1774 | Tide Race | A strong tidal current or a channel in which such a current flows. [14] |
| 1775 | Tide: Ebb | See tide: falling. [14] |
| 1776 | Tide: Low | See low water. [14] |
| 1777 | Tie Point | Point of closure of a survey either on itself or on another survey. [14] |
| 1778 | Time Ball | A visual time signal in the form of a ball. [14] |
| 1779 | Time Zone | See zone. [14] |
| 1780 | Tolerance | The maximum allowable variation from a standard or from specified conditions. [14] |
| 1781 | True Wind | Wind vector in relation to the earth's surface. For a moving object it is the vector sum of the relative wind and the velocity of the object. [14] |
| 1782 | Tuff-Cone | See tuff. [14] |
| 1783 | Turbidite | Turbidity current deposits, characterized by both vertically and horizontally graded bedding. [14] |
| 1784 | Turbidity | Reduced water clarity resulting from the presence of suspended matter. Water is considered turbid when its load of suspended matter is visibly conspicuous, but all waters contain some suspended matter and therefore are turbid. Reduced transparency of the atmosphere, caused by absorption and scattering of radiation by solid or liquid particles, other than clouds, held there in suspension. [14] |
| 1785 | Type Face | A type of print, such as roman, egyptian, caslon, etc. [14] |
| 1786 | Uncovered | (Adj.). Above water. The opposite is submerged. [14] |
| 1787 | Warm Pool | A body of warm water entirely surrounded by cold water. [14] |
| 1788 | Water Sky | Typical dark patches and strips on low clouds over a water area enclosed in ice or behind its edge. [14] |
| 1789 | Waterline | The line marking the junction of land and water. The line along which the surface of the water touches a vessel's hull. Also written as two words. [14] |
| 1790 | Wave Base | The greatest depth at which sediment on the sea floor can just be stirred by the oscillating water. [14] |
| 1791 | Wavemeter | An instrument for measuring waves. One used for ocean waves usually measures height and period; one used for electromagnetic or sound waves usually measures length. Also written as two words. [14] |
| 1792 | Whirlpool | Water in rapid rotary motion. See eddy. [14] |
| 1793 | Whirlwind | General term for a small-scale rotating column of air. [14] |
| 1794 | Wind Farm | a collection of wind turbines that are collocated and are organized as a single power generation unit. [14] |
| 1795 | Wind Vane | An instrument used to indicate wind direction. [1] |
| 1796 | Air Camera | A camera specially designed for use in flying craft. [14] |
| 1797 | Alkalinity | The number of milliequivalents of hydrogen ions that are neutralized by 1 kilogram of sea water at 20°c when a large excess of acid is added. [14] |
| 1798 | Anemometer | Instrument used in the measurement of wind speed or of wind speed and direction. See also anemograph. [14] |
| 1799 | Annotation | Any marking on illustrative material for the purpose of clarification, such as numbers, letters, symbols, and signs. [14] |
| 1800 | Antiselena | Luminous phenomenon analogous to anthelion, the luminary being the moon. [14] |
| 1801 | Anti-Trade | Air current with a westerly component which in various subtropical regions of either hemisphere sometimes blows above the trade wind. [14] |
| 1802 | Astrometry | That branch of astronomy dealing with the determination of positions and motions of celestial bodies, including the earth. [14] |
| 1803 | Automation | The technique of improving human productivity in the processing of materials, energy and information, by utilizing in various degrees elements of automatic control, and of automatically executed product programming. [14] |
| 1804 | Bathymeter | An instrument primarily designed for measuring depth of water. [14] |
| 1805 | Beam Width | The angular measure of the transverse section of a beam (usually in the main lobe) lying within directions corresponding to specified values of field strength relative to the maximum. [14] |
| 1806 | Bold Coast | A prominent land mass that rises steeply from the sea. [14] |
| 1807 | Borderland | A region adjacent to a continent, normally occupied by or bordering a shelf and sometimes emerging as islands, that is irregular or blocky in plan or profile, with depths well in excess of those typical of a shelf. [14] |
| 1808 | Bottom Ice | See anchor ice. [14] |
| 1809 | Buoy: Life | A buoy intended to keep persons afloat. Also called life jacket. [14] |
| 1810 | Cable Buoy | See buoy. [14] |
| 1811 | Cable Sign | A sign on a post marking the point from which a cable runs under water. [14] |
| 1812 | Calcareous | (adj). Composed of or containing calcium or calcium carbonate. [14] |
| 1813 | Calculator | A machine for performing arithmetical operations usually more complex than that done by an adding machine; a calculating machine, which may be mechanical, electrical, electronic or a combination of all three. A person who calculates. [14] |
| 1814 | Cavitation | The turbulent formation, generally mechanically induced, including growth and collapse of bubbles in a fluid, and occurring when the static pressure at any point in fluid flow is less than fluid vapor pressure. [14] |
| 1815 | Cgs System | See centimeter-gram-second (cgs) system. [14] |
| 1816 | Chart: New | The first publication of a chart. [14] |
| 1817 | Chlorosity | The property of sea water corresponding to the chlorinity expressed as grams per litre at 20°. [14] |
| 1818 | Choppy Sea | The state of the sea caused by interaction of waves running in different directions. [14] |
| 1819 | Civil Time | See time. [14] |
| 1820 | Civil Year | See year. [14] |
| 1821 | Colatitude | The complement of the latitude, or 90° minus the latitude. [14] |
| 1822 | Comparator | An instrument for measuring a dimension in terms of a standard. An optical instrument for measuring rectangular or polar coordinates of points on any plane surface, such as a photographic plate. [14] |
| 1823 | Conduction | The transfer of heat by molecular activity from one substance to another, or through a substance. Transfer is always from warmer to colder regions. [1] |
| 1824 | Confluence | Flowing together. The place where two or more rivers, streams, etc. Unite. In meteorology, progressive drawing together of the streamlines in the direction of flow. [14] |
| 1825 | Contouring | The process of establishing lines representing equal values of a quantity on a map or chart. [14] |
| 1826 | Coral Head | A massive mushroom or pillar shaped coral growth. [14] |
| 1827 | Cordillera | A range or system of mountains. [14] |
| 1828 | Covariance | The arithmetic mean or expected value of the product of the deviations of corresponding values of two variables from their respective mean values. [14] |
| 1829 | Cross Wind | Wind which blows in a direction perpendicular to that of the motion of a moving object, relative to the earth's surface. [14] |
| 1830 | Crosslines | Sounding lines that cross the main system of lines at either right angles or at an oblique angle to serve as a check on the accuracy of the work. [14] |
| 1831 | Dark Slide | See slide: dark. [14] |
| 1832 | Day: Civil | A mean solar day beginning at midnight. [14] |
| 1833 | Day: Lunar | The duration of one rotation of the earth on its axis, with respect to the moon. Its average length is about 24h50m of mean solar time. Also called tidal day. The duration of one rotation of the moon on its axis, with respect to the sun. [14] |
| 1834 | Day: Tidal | See day: lunar and tidal day. [14] |
| 1835 | Dead Ahead | Bearing 000° relative. If the bearing is approximate, the term ahead should be used. [14] |
| 1836 | Dead Water | The phenomenon which occurs when a ship of low propulsive power negotiates water which has a thin layer of fresher water over a deeper layer of more saline water. As the ship moves, part of its energy goes into generation of an internal wave which causes a noticeable drop in efficiency of propulsion. [14] |
| 1837 | Diagenesis | The chemical and physical changes that sediments undergo after their deposition, by lithification. [14] |
| 1838 | Dispersion | The separation of radiant energy into its various components. In optics, the separation of light into its component colors by its passage through a diffraction grating or by refraction such as that provided by a prism. In oceanography, the separation of a complex surface gravity wave disturbance into its component parts. [14] |
| 1839 | Divider(S) | Measuring compasses having both legs pointed, used principally for measuring distances and coordinates. [14] |
| 1840 | Drift Buoy | A data collection buoy which is not moored to the sea bottom, but drifting freely in response to currents, tides, and wind. [14] |
| 1841 | Drift Lead | See lead. [14] |
| 1842 | Earth Tide | See tide. [14] |
| 1843 | Exit Pupil | The image of aperture stop formed by all the lens elements on the image side of the aperture stop. [14] |
| 1844 | Fair Sheet | See fair chart. [14] |
| 1845 | Fix: Split | A fix obtained by measuring two angles to four objects whose positions are known, i.e. With no common center object. [14] |
| 1846 | Float Well | A vertical pipe or box with a relatively small opening in the bottom, used to enclose the float of a tide gauge so the float will be little affected by nontidal motions of the water. Synonymous with stilling well. [14] |
| 1847 | Form Lines | Lines drawn to represent the shape of terrain; unlike contour lines, these are drawn without regard to a true vertical datum or regular vertical interval. [14] |
| 1848 | Foul Berth | A berth in which a vessel cannot swing to her anchor or moorings without fouling another vessel or striking an obstruction. [14] |
| 1849 | Geophysics | The study of the physical characteristics and properties of the earth. [14] |
| 1850 | Glaciology | The study of snow and ice on the earth's surface, with specific concentration on the regime of active glaciers. [14] |
| 1851 | Gold Slide | An adjustable attachment to a mercurial barometer for giving resultant of corrections for index error, height of instrument above sea level, variation in gravity due to latitude, temperature. Invented by col. E. Gold. [14] |
| 1852 | Goniometer | An instrument for measuring angles. A pick-up coil which eliminates the necessity of having to rotate a radio direction finder antenna to determine direction. [14] |
| 1853 | Gravimeter | A weighing device or instrument of sufficient sensitivity to register variations in the weight of a constant mass when the mass is moved from place to place on the earth and thereby subjected to the influence of gravity at those places. Also called gravity meter. [14] |
| 1854 | Grid Ticks | Short lines indicating where selected grid lines intersect the neat line. [14] |
| 1855 | Ground Ice | See anchor ice. [14] |
| 1856 | Ground Log | See log. [14] |
| 1857 | Guard Lock | See tide lock. [14] |
| 1858 | Gyro Pilot | An automatic pilot controlled by gyroscopes. An automatic device for steering a vessel by means of control signals from a gyroscopic compass. [14] |
| 1859 | Hinterland | The district behind that lying along the coast; the back country. [14] |
| 1860 | Hummocking | Pressure process by which level ice becomes broken up into hummocks. [14] |
| 1861 | Hydrometer | An instrument for determining the specific gravity of liquids. [14] |
| 1862 | Hygrometer | An instrument for measuring the humidity of the air. See also psychrometer. [14] |
| 1863 | Hypsometry | The determination of elevations above sea level. Generally applied to the determination of eleva-tions through the measurement of air pressure by observing the boiling point of a liquid. [14] |
| 1864 | Hysteresis | Retardation or lag in the effect of changing forces, as in ship's magnetism induced by the earth's magnetic field. [14] |
| 1865 | Ice Nuclei | Particles that act as nuclei for the formation of ice crystals in the atmosphere. [1] |
| 1866 | Infrasonic | (Adj.). Having a frequency below the audible range. [14] |
| 1867 | Insolation | Amount of direct solar radiation incident per unit horizontal area at a given level. Downward-directed solar radiation (global radiation). [14] |
| 1868 | Invar Tape | See tape. [14] |
| 1869 | Invar Wire | See wire. [14] |
| 1870 | Isodynamic | (Adj.). Of or pertaining to equality of force. [14] |
| 1871 | Isohalsine | See isohaline. [14] |
| 1872 | Jet Streak | A region of high wind speed that moves through the axis of a jet stream. Also called jet maximum. [1] |
| 1873 | Kite Otter | A multi-plane device which can be used either as a kite or as an otter depending on the way it is slung. See oropesa sweep. [14] |
| 1874 | Kymatology | The science of waves and wave motion. [14] |
| 1875 | Lead (Led) | A navigable passage through ice. The amount one cyclic motion is ahead of another, expressed in degrees. [14] |
| 1876 | Lead: Fish | A fish-shaped sounding lead which reduces to a minimum the inclination of the wire when trailed, making unnecessary its removal from the water between soundings. [14] |
| 1877 | Lead: Hand | A light sounding lead (3 to 5 kilos) having usually a line of not more than 40 to 50 meters. [14] |
| 1878 | Light-Year | A unit of length equal to the distance light travels in one year. This unit is used as a measure of stellar distance. [14] |
| 1879 | Lunar Tide | See under tide. [14] |
| 1880 | Macroscale | The normal meteorological synoptic scale for obtaining weather information. It can cover an area ranging from the size of a continent to the entire globe. [1] |
| 1881 | Making Way | Progressing through the water. [14] |
| 1882 | Map: Index | In aerial photography, a map showing the location and numbers of flight strips and photographs. [14] |
| 1883 | Microburst | A strong localized downdraft (downburst) less than 4 km wide that occurs beneath thunderstorms. A strong downburst greater than 4 km across is called a macroburst. [1] |
| 1884 | Microphone | An electroacoustic device containing a transducer which is actuated by sound waves and delivers essentially equivalent electric waves. [14] |
| 1885 | Microscale | The smallest scale of atmospheric motions. [1] |
| 1886 | Mixed Seas | The state of the sea resulting from the interaction of wind, waves, and swell. [14] |
| 1887 | Mixed Tide | See tide. [14] |
| 1888 | Mobile Rig | See rig. [14] |
| 1889 | Mock Moons | Name given sometimes to paraselenae, parantiselenae and antiselenae when they are bright. [14] |
| 1890 | Monitoring | Checking of the operation and performance of an electronic system through reception of its signals. [14] |
| 1891 | Nadir: Map | The map position for the ground nadir. [14] |
| 1892 | Nanosecond | A thousand millionth of a second. [14] |
| 1893 | Nautophone | A horn having a diaphragm oscillated by electricity. [14] |
| 1894 | New Survey | See resurvey. [14] |
| 1895 | Niggerhead | Large blocks of coral torn loose from the outer face of a reef and tossed on to the reef flat by storm waves or tsunamis. The blocks are blackened by a crust of lichens after detachment from the reef. [14] |
| 1896 | Noon: Mean | Twelve o'clock mean time. [14] |
| 1897 | Ocean Eddy | A moving or stationary local rotating formation where water predominantly moves along circular paths. [14] |
| 1898 | Open Sound | A bay similar to a lagoon but with large openings between the protecting islands. [14] |
| 1899 | Open Water | A relatively large area of free navigable water in an ice-encumbered sea. In US Terminology, an area of sea with less than one-tenth ice concentration. [14] |
| 1900 | Opisometer | A recording device designed to measure by revolutions of a small wheel, continuous linear distances on a map. Used in measuring the length of shoreline by closely following all the indentations and sinuosity’s of the shore. [14] |
| 1901 | Outgassing | The release of gases dissolved in hot, molten rock. [1] |
| 1902 | Ozone (O3) | An almost colorless gaseous form of oxygen with an odor similar to weak chlorine. The highest natural concentration is found in the stratosphere where it is known as stratospheric ozone. It also forms in polluted air near the surface where it is the main ingredient of photochemical smog. Here, it is called tropospheric ozone. [1] |
| 1903 | Ozone (O3) | An almost colorless gaseous form of oxygen with an odor similar to weak chlorine. The highest natural concentration is found in the stratosphere where it is known as stratospheric ozone. It also forms in polluted air near the surface where it is the main ingredient of photochemical smog. Here, it is called tropospheric ozone. [1] |
| 1904 | Ozone Hole | A sharp drop in stratospheric ozone concentration observed over the Antarctic during the spring. [1] |
| 1905 | Pantograph | An instrument for copying a chart, drawing, etc., to any desired scale within the limits of the instrument. [14] |
| 1906 | Paraselene | Optical phenomenon of the halo family, similar to but less brilliant than the parhelion, the luminary being the moon. [14] |
| 1907 | Pass Point | In photogrammetry, a point whose horizontal and/or vertical position is determined from photo-graphs by photogrammetrically methods and which is intended for use (as in the manner of a supplemental control point) in the orientation of other photographs. [14] |
| 1908 | Passometer | A pocket-size instrument which registers the number of steps taken by the pedestrian carrying it. See pedometer. [14] |
| 1909 | Phonometer | An instrument for measuring the intensity or frequency of sounds. [14] |
| 1910 | Photo Base | The length of the air base as represented on a photograph. [14] |
| 1911 | Photoindex | A mosaic made by assembling individual photographs, with accompanying designations, into their proper relative positions and copying the assembly photographically at a reduced scale. [14] |
| 1912 | Photometer | An instrument used in measuring the intensity of light, especially in determining the relative intensity of different lights. [14] |
| 1913 | Piggot Gun | A coring instrument for obtaining deep-sea bottom samples. This instrument uses an explosive charge to drive a metal bit into the bottom at the instant the sharp end of the bit strikes the bottom. [14] |
| 1914 | Planimeter | A mechanical integrator for measuring the area of a plane surface. [14] |
| 1915 | Planimetry | The measurement of plane surfaces. The plan details of a map. [14] |
| 1916 | Promontory | A high point of land extending into a body of water. A cape. [14] |
| 1917 | Pycnocline | A vertical positive density gradient in some layer of a body of water, which is appreciably greater than gradients above and below it. [14] |
| 1918 | Radar Buoy | See buoy. [14] |
| 1919 | Radar Dome | A dome shaped structure used to protect the antenna of a radar installation. [14] |
| 1920 | Radar Line | See radar guided track. [14] |
| 1921 | Radar View | A depiction (photographic reproduction or drawing) of appearance of landmarks on the ppi scope of a radar set at a particular geographic location, intended to facilitate the identification of the coast. This can aid the navigator to identify or match his own radar image of these same landmarks. [14] |
| 1922 | Radarsonde | Equipment used for determining high-level winds, by means of radar aimed at a target carried by a free balloon. [14] |
| 1923 | Radio Aids | An aid to navigation transmitting information by radio waves. [14] |
| 1924 | Radio Mast | A tower, pole, or other structure for elevating an antenna. [14] |
| 1925 | Radiometer | An instrument for measuring the intensity of radiant energy. [14] |
| 1926 | Real Image | See image. [14] |
| 1927 | Region A,B | Within the iala maritime buoyage system there are two international buoyage regions, designated as region a and region b, where lateral marks differ only in the colors of port and starboard hand marks. [14] |
| 1928 | Relief Map | See map. [14] |
| 1929 | Right Bank | Of a river, the bank on the right-hand side as one proceeds downstream. [14] |
| 1930 | Rock Borer | A member of any of several families of bivalves that live in cavities they bore in soft rock, concrete and other material. [14] |
| 1931 | Rock Flour | Finely ground rock particles, chiefly silt size, resulting from glacial abrasion. A component of marine deposits off glacial stream mouths. [14] |
| 1932 | Rocky Area | An area with a rocky bottom. [14] |
| 1933 | Rod: Range | See range rod. [14] |
| 1934 | Roll Cloud | A dense, roll-shaped, elongated cloud that appears to slowly spin about a horizontal axis behind the leading edge of a thunderstorm's gust front. [1] |
| 1935 | Rotten Ice | Sea ice which has become honeycombed in the course of melting, and which is in an advanced state of disintegration. [14] |
| 1936 | Salt Marsh | Flat, poorly drained coastal swamps which are flooded by most high tides. [14] |
| 1937 | Sea Valley | See valley. [14] |
| 1938 | Seamanship | A general term for the art by which vessels are handled. [14] |
| 1939 | Shadow Pin | A small rod or pin used to cast a shadow on an instrument, such as a magnetic compass or sun com-pass, to determine the direction of the luminary; a gnomon. [14] |
| 1940 | Shore Lead | A lead between pack ice and the shore, or between pack ice and a narrow fringe of fast ice. [14] |
| 1941 | Sill Depth | The greatest depth over a sill. [14] |
| 1942 | Sketch Map | See map. [14] |
| 1943 | Solar Apex | See apex. [14] |
| 1944 | Solar Cell | A cell using the solar light or other light energy for conversion into electric energy. [14] |
| 1945 | Solar Tide | See tide. [14] |
| 1946 | Sonic Boom | A loud explosive-like sound caused by a shock wave emanating from an aircraft (or any object) traveling at or above the speed of sound. [1] |
| 1947 | Stadimeter | An instrument used to measure the distance from the observer to a more-or-less distant object, such as a vessel, when the height of a specified part of the latter (e.g. The mast) is known. It is in effect a hand-held range finder. [14] |
| 1948 | Star Chart | See chart. [14] |
| 1949 | Statoscope | A highly sensitive barometer or altimeter for measuring slight variations in pressure or altitude. [14] |
| 1950 | Stereogram | A stereoscopic pair of photographs or drawings correctly oriented and mounted or projected for stereoscopic viewing. [14] |
| 1951 | Sun Pillar | A vertical streak of light extending above (or below) the sun. It is produced by the reflection of sunlight off ice crystals. [1] |
| 1952 | Supersonic | (Adj.). Designating or of a speed greater than the speed of sound. [14] |
| 1953 | Swash Mark | The thin wavy line of fine sand, mica scales, bits of seaweed, etc., left by the uprush when it recedes from its upward limit of movement on the beach. [14] |
| 1954 | Swept Area | An area that has been determined to be clear of navigational dangers to a specified depth [14] |
| 1955 | Tablemount | A seamount having a comparatively smooth flat top. Also called guyot. [14] |
| 1956 | Tabulation | Orderly arrangement as in a table. [14] |
| 1957 | Tachometer | A device that indicates or measures the revolutions per minute of a revolving shaft or the velocity of a machine. [14] |
| 1958 | Tape: Base | See base tape (or wire). [14] |
| 1959 | Thermogram | Record made by a thermograph. [14] |
| 1960 | Tidal Bore | See bore. [14] |
| 1961 | Tidal Flat | A marsh or sandy or muddy coastal flatland which is covered and uncovered by the rise and fall of the tide. [14] |
| 1962 | Tide Bulge | See tide wave. [14] |
| 1963 | Tide Crack | The fissure at the line of junction between an immovable icefoot or ice wall and fast ice, the latter being subject to the rise and fall of the tide. [14] |
| 1964 | Tide Curve | Any graphic representation of the rise and fall of the tide. Time is generally represented by the abscissae and the height of the tide by ordinates. For normal tides the curve so produced approximates a sine curve. Also called marigram. [14] |
| 1965 | Tide: Half | The condition or time of the tide when at the level midway between any given high tide and the following or preceding low tide. [14] |
| 1966 | Tide: High | See high water. [14] |
| 1967 | Tide-Bound | (Adj.). Unable to proceed because of insufficient depth of water due to tidal action. [14] |
| 1968 | Tilt: Base | In photogrammetry, the inclination of the air base with respect to the horizontal. [14] |
| 1969 | Time: Zone | The local mean time of a reference or zone meridian, whose time is kept throughout a designated zone. The zone meridian is usually the nearest meridian whose longitude is exactly divisible by 15°. [14] |
| 1970 | Trajectory | The curved path of something hurtling through space. In meteorology, curve traced by the successive positions of a moving particle of air. Curve traced by the successive positions of the center of a selected synoptic system, such as a depression. In oceanography, the path followed by moving water particles. In electronics the path followed by electrons emanating from the cathode as in an electron tube. [14] |
| 1971 | Undercliff | A terrace or lower cliff formed by a landslide. Also written as two words. [14] |
| 1972 | Upper Limb | See limb. [14] |
| 1973 | Vectograph | A stereoscopic photograph composed of two superimposed images which polarize light in planes 90° apart. When these images are viewed through polaroid spectacles with the polarization axes at right angles, an impression of depth is obtained. [14] |
| 1974 | Vignetting | In photography, a gradual reduction in density of parts of a photographic image due to the stopping of some of the rays entering the lens. [14] |
| 1975 | Waterspout | A column of rotating wind over water that has characteristics of a dust devil and a tornado. [1] |
| 1976 | Wave Setup | The result of 'sets' of waves transporting water shoreward and raising the sea level. [16] |
| 1977 | Wave: Edge | An ocean wave travelling parallel to a coast, with crests normal to the coastline. Such a wave has a height that diminishes rapidly seaward and is negligible at a distance of one wavelength offshore. [14] |
| 1978 | Wave: Free | A wave that continues to exist after the generating force has ceased to act, in contrast with a forced wave that is generated and maintained by a continuous force. A free wave on a water surface is one created by a sudden impulse, thereafter influenced only by friction, the dimensions of the basin, and the dispersive character of the water medium it moves in. Most ocean surface waves except tidal waves are free waves. See oscillation. [14] |
| 1979 | Wave: Tide | See tide. [14] |
| 1980 | Wave: Wind | A wave resulting from the action of wind on a water surface. See fetch. [14] |
| 1981 | Winter Ice | More or less unbroken, level sea ice of not more than one winter's growth originating from young ice. Thickness from 15 cm to 2 m. [14] |
| 1982 | Wire: Base | See base tape (or wire). [14] |
| 1983 | Wreck Buoy | A buoy marking the location of a wreck. [14] |
| 1984 | Xerography | A process of electrostatic printing which employs a special selenium-coated plate, useable many times over. [14] |
| 1985 | Xerophytes | Drought-resistant vegetation. [1] |
| 1986 | Abyssal Gap | A gap in a sill, ridge, or rise that lies between two abyssal plains. [14] |
| 1987 | Aggradation | See accretion. [14] |
| 1988 | Agonic Line | The line through all points on the earth's surface at which the magnetic variation is zero. [14] |
| 1989 | Air Almanac | See under almanac. [14] |
| 1990 | Amici Prism | A prism which deviates the rays of light through 90° and because of its shape inverts the image. See roof prism. [14] |
| 1991 | Anchor Buoy | A buoy marking the position of an anchor. [14] |
| 1992 | Angle: Hour | See hour angle. [14] |
| 1993 | Antipode(S) | Place(s) on the surface of the earth directly opposite to each other. [14] |
| 1994 | Apex: Solar | The point of the celestial sphere towards which the solar system as a whole is moving. It lies in the constellation of Hercules. [14] |
| 1995 | Aquaculture | The cultivation of aquatic fauna and flora. [14] |
| 1996 | Axis: Polar | In a system of polar or spherical coordinates, the primary axis of direction. [14] |
| 1997 | Baroclinity | The condition and type of motion in which pressure is not constant on surfaces of constant density, e.g. Internal waves. [14] |
| 1998 | Barrel Buoy | See buoy. [14] |
| 1999 | Bathysphere | A diving sphere for deep-sea observations. [14] |
| 2000 | Box Sextant | A small portable instrument used for approximate measurement of angles. [14] |
| 2001 | Buoy: Cable | A buoy used to indicate the run of a submarine cable. [14] |
| 2002 | Buoy: Radar | A buoy with a cluster of radar reflectors. [14] |
| 2003 | Candlepower | Luminous intensity expressed in candelas. Also written as two words. [14] |
| 2004 | Chart Scale | See scale. [14] |
| 2005 | Chart: Fair | See fair chart. [14] |
| 2006 | Chart: Grid | A chart only showing a cartographic grid on its inner border. [14] |
| 2007 | Chart: Star | A representation, on a flat surface, of the celestial sphere or a part of it, showing the positions of the stars and sometimes other features of the celestial sphere. [14] |
| 2008 | Chlorophyll | The green pigment contained in the leaves of plants. See photosynthesis. [14] |
| 2009 | Chronograph | An instrument for measuring and recording time or time intervals. [14] |
| 2010 | Circle: Dip | See dip circle. [14] |
| 2011 | Climatology | Study of climates (causes, variations, distributions, types, etc.). [14] |
| 2012 | Coalescence | The merging of cloud droplets into a single larger droplet. [1] |
| 2013 | Coast Chart | See chart. [14] |
| 2014 | Contour Map | See map. [14] |
| 2015 | Core Sample | See core. [14] |
| 2016 | Cosmic Dust | Very fine particles of solid matter in any part of the universe, including meteoric dust and zodiacal light particles in the solar system, interstellar matter of uncertain origin in the milky way galaxy, and accumulation of dark matter in other galaxies. [14] |
| 2017 | Customhouse | The office, especially in harbors, at which customs are collected. [14] |
| 2018 | Danger Buoy | See isolated danger mark. [14] |
| 2019 | Danger Line | A line drawn on a chart, to indicate the limits of safe navigation for a vessel of specific draft. A dotted line on a chart to emphasize the presence of an obstruction. [14] |
| 2020 | Dart Leader | The discharge of electrons that proceeds intermittently toward the ground along the same ionized channel taken by the initial lightning stroke. [1] |
| 2021 | Dead Astern | Bearing 180° relative. If the bearing is approximate, the term astern should be used. Also called right astern. [14] |
| 2022 | Demagnetize | (v.t.). To remove magnetism. The opposite is magnetize. [14] |
| 2023 | Depth Gauge | See gauge. [14] |
| 2024 | Design Wave | Deterministic wave used for the design of an offshore structure. [14] |
| 2025 | Diapositive | A positive photograph on a transparent medium. One which has a right reading image when viewed through the base support. [14] |
| 2026 | Diffraction | The bending of the rays of radiant energy around the edges of an obstacle, or when passing near the edges of an opening, or through a small hole or slit, resulting in the formation of a spectrum, or arrangement by wavelength of component waves, producing, for visible wavelengths, the chromatic spectrum. The bending of a wave as it passes an obstruction. [14] |
| 2027 | Direct Wave | See wave. [14] |
| 2028 | Discrepancy | A difference between results of duplicate or comparable measures of a quantity. The difference in computed values of a quantity obtained by different processes using data from the same survey. [14] |
| 2029 | Dish Aerial | A parabolic aerial for the receipt and transmission of high frequency radio signals. [14] |
| 2030 | Dixie Alley | Region in the southern united states, typically over mississippi and alabama, where tornadoes often form. [1] |
| 2031 | Double Tide | See tide. [14] |
| 2032 | Draft Marks | Numerals at the bow and stern of a vessel that indicate the depth to which the vessel is submerged. [14] |
| 2033 | Draughtsman | See draftsman. [14] |
| 2034 | Driver Tube | See driver rod. [14] |
| 2035 | Drying Line | The line marking the transit from water to land; usually the low-water line. [14] |
| 2036 | Duck Blinds | Non floating structures used for concealing waterfowl hunters. They usually consist of a wooden framework covered with brush. They are essentially unreported to any charting authority when built. They are unlighted and often constructed in navigable water without regard to the possible hazard they pose, especially to the small craft operator. Many are substantial structures built on piles. Even after they are eventually reduced to ruins the pilings may persist for years. [14] |
| 2037 | Dx90-Format | Format for supply or interchange of digital cartographic data. Dx90 provides two modes: the sequential, and the chain mode. [14] |
| 2038 | Dynamometer | An apparatus for measuring force or energy. [14] |
| 2039 | Earth Light | Feeble light of the dark part of the moon's disc produced by the solar light reflected by the earth including the atmosphere. Also written as one word. Also called earthshine. [14] |
| 2040 | Electrotape | A trade name for a precise electronic distance measuring device operating on the same principle as the tellurometer. Originally designated as micro-dist. [14] |
| 2041 | Erect Image | See image. [14] |
| 2042 | Exit Window | The image of the field stop formed by all the lens elements on the image side of the field stop. [14] |
| 2043 | Field Chart | See chart. [14] |
| 2044 | Field Sheet | The hydrographer's or topographer's work sheet; it presents a graphic display of all surface and subsurface features in the area being surveyed. See also boat sheet. [14] |
| 2045 | Flare Stack | A tall structure used for burning-off waste oil or gas. [14] |
| 2046 | Flash Flood | A flood that rises and falls quite rapidly with little or no advance warning, usually as the result of intense rainfall over a relatively small area. [1] |
| 2047 | Float Gauge | See gauge. [14] |
| 2048 | Focal Point | See focus. [14] |
| 2049 | Fog Patches | Fog in banks irregularly distributed. [14] |
| 2050 | Fog Trumpet | A trumpet used as a fog signal. [14] |
| 2051 | Fog Whistle | A whistle used as a fog signal. [14] |
| 2052 | Forced Wave | See wave. [14] |
| 2053 | Forward Lap | See overlap. [14] |
| 2054 | Foul Bottom | A hard, uneven, rocky or obstructed bottom having poor holding qualities for anchors, or one having rocks or wreckage that would endanger an anchored vessel. [14] |
| 2055 | Foul Ground | An area over which it is safe to navigate but which should be avoided for anchoring, taking the ground or ground fishing. [14] |
| 2056 | Frost Smoke | Fog-like clouds, due to the contact of cold air with relatively warm sea water, which appear over newly formed leads and pools, or leeward, of the ice edge, and which may persist while slush or sludge and young ice are forming. [14] |
| 2057 | Gauge: Rain | Instrument for measuring the depth of water from precipitation supposed distributed over a hori-zontal impervious surface and not subject to evaporation. Also written as one word. [14] |
| 2058 | Glacier Ice | Any ice floating on the sea as an iceberg, which originates from a land glacier. Also called land ice. [14] |
| 2059 | Green Flash | A small green color that occasionally appears on the upper part of the sun as it rises or sets. [1] |
| 2060 | Grid Course | See course. [14] |
| 2061 | Gross Error | See error. [14] |
| 2062 | Gulf Stream | A warm, swift, narrow ocean current flowing along the east coast of the united states. [1] |
| 2063 | Hadley Cell | A thermal circulation proposed by George Hadley to explain the movement of the trade winds. It consists of rising air near the equator and sinking air near 30° latitude. [1] |
| 2064 | Hard Bottom | The sea floor not covered by unconsolidated sediment. [14] |
| 2065 | Heat Stroke | A physical condition induced by a person's overexposure to high air temperatures, especially when accompanied by high humidity. [1] |
| 2066 | Hindcasting | Method of simulating historical (metocean) data for a region through numerical modelling [14] |
| 2067 | Hydrometeor | Meteor consisting of an ensemble of liquid or solid water particles falling through or suspended in the atmosphere, blown by the wind from the earth's surface or deposited on objects on the ground or in the free air. [14] |
| 2068 | Hypothermia | The deterioration in one's mental and physical condition brought on by a rapid lowering of human body temperature. [1] |
| 2069 | Ice Cluster | A concentration of sea ice covering hundreds of square kilometers, which is found in the same region every summer. [14] |
| 2070 | Image: Real | An image actually produced and capable of being shown on a surface, as in a camera. [14] |
| 2071 | Indentation | A recess in a coastline. [14] |
| 2072 | Index Chart | See chart. [14] |
| 2073 | Index Shade | On a sextant, one of the pivoting coloured glasses which can be swung before the index mirror for reducing the glare of the sun. [14] |
| 2074 | Iridescence | Brilliant spots or borders of colors, most often red and green, observed in clouds up to about 30° from the sun. [1] |
| 2075 | Jack-Up Rig | A rig which provides a stable drilling structure in shallow waters by extending supporting legs onto the seabed. The legs are retracted when the rig is under tow. [14] |
| 2076 | Kelvin Wave | A long ocean wave whose amplitude decreases from right to left along the wave crest when viewed in the direction of travel in the northern hemisphere and from left to right in the southern hemisphere. The component of gravity acting down the slope is exactly balanced by the deflecting force of the earth's rotation, the Coriolis force. [14] |
| 2077 | Lake Breeze | See sea breeze. [14] |
| 2078 | Latent Heat | The heat that is either released or absorbed by a unit mass of a substance when it undergoes a change of state, such as during evaporation, condensation, or sublimation. [1] |
| 2079 | Lead (Lã¨D) | A heavy, soft, malleable, bluish-grey metallic chemical element. Anything made of this metal, such as a weight for sounding depths of water. [14] |
| 2080 | Lead: Drift | Sounding lead dropped to bottom, to indicate movement of a vessel. [14] |
| 2081 | Least Count | The finest reading that can be made directly (without estimation) from a vernier or micrometer. [14] |
| 2082 | Light Float | A boat-like structure used instead of a light buoy in waters where strong streams or currents are experienced, or when a greater elevation than that of a light buoy is necessary. [14] |
| 2083 | Light: Rear | See light(s): range. [14] |
| 2084 | Line Squall | Squall which occurs along a squall line. [14] |
| 2085 | Lithosphere | The solid, rocky part of the earth; earth's crust distinguished from atmosphere, hydrosphere. [14] |
| 2086 | Log: Ground | A device for determining the course and speed made good over the ground in shallow water, consisting of a lead attached to a line. The lead is thrown overboard and allowed to rest on the bottom. The course being made good is indicated by the direction the line tends and the speed by the amount of line paid out in unit time. [14] |
| 2087 | Log: Patent | Former name for a towed log. Any mechanical log, particularly a taffrail log. [14] |
| 2088 | Magnetogram | An analogue time record of the temporal variations in a magnetic element measured at a magnetic observatory. [14] |
| 2089 | Map: Relief | A map emphasizing relief or relative elevations. See relief model. [14] |
| 2090 | Map: Sketch | A map drawn freehand and greatly simplified which, although preserving the essential space relationships, does not truly preserve scale or orientation. [14] |
| 2091 | Marine Farm | See fish farm. [14] |
| 2092 | Mesoclimate | The climate of an area ranging in size from a few acres to several square kilometers. [1] |
| 2093 | Meter Wheel | A special block used to measure paid out sampling line at oceanographic stations. [14] |
| 2094 | Microsecond | One millionth of a second. [14] |
| 2095 | Microseisms | More or less persistent feeble earth tremors caused by natural sources such as atmospheric pressure systems or waves. [14] |
| 2096 | Mixed Layer | In oceanography, the surface layer of virtually isothermal water, which frequently exists above the thermocline. The thickness of the layer is dependent on the temperature gradient. [14] |
| 2097 | Mud Snapper | See snapper. [14] |
| 2098 | North: Grid | An arbitrary reference direction used with grid navigation. The northerly or zero direction indicated by the grid datum of directional reference. [14] |
| 2099 | North: True | The direction of the north geographic pole. [14] |
| 2100 | Omnibearing | The magnetic bearing of an omnirange. [14] |
| 2101 | Opalescence | Whitish colour of the atmosphere and a slight change of the apparent colour of objects with respect to normal (for example, bluish colour of an object normally black or dark) produced by the scattering of light by small particles held in suspension in the atmosphere. [14] |
| 2102 | Overrunning | A condition that occurs when air moves up and over another layer of air. [1] |
| 2103 | Oxygen (O2) | A colorless and odorless gas that occupies about 21 percent of dry air in the lower atmosphere. [1] |
| 2104 | Pacific Air | Cool, moist air that originates over the Pacific Ocean, moves eastward, then descends the rocky mountains and moves over the plains as dry, stable, relatively cool air. [1] |
| 2105 | Pancake Ice | Pieces of new ice, usually approximately circular, about 30 cm to 3 m across, and with raised rims, due to the pieces striking against each other as the result of wind and swell. [14] |
| 2106 | Pecked Line | In cartography, a symbol consisting of a line broken at regular intervals. [14] |
| 2107 | Pencil Beam | A beam in which the radiant energy is concentrated in an approximately conical or cylindrical portion of space of relatively small diameter. This type beam is used for many revolving navigational lights. [14] |
| 2108 | Percolation | The process by which water is forced by wave action through the interstices of the bottom sediment and has a tendency to reduce wave heights. [14] |
| 2109 | Photosphere | The visible surface of the sun and direct source of almost all its radiation. It is a gaseous layer some 400 km thick, below which the sun becomes opaque. [14] |
| 2110 | Pillar Buoy | A buoy composed of a tall central structure on a broad flat base. [14] |
| 2111 | Pilot Chart | See chart. [14] |
| 2112 | Pivot Point | After a ship has assumed its drift angle in a turn, the point on the centerline between the bow and the center of gravity at which the resultant of the velocities of rotation and transaction is directed along the centerline. To an observer on board, the ship appears to rotate about this point. [14] |
| 2113 | Plate Level | See level. [14] |
| 2114 | Pluviograph | Rain gauge which includes an arrangement for the time recording of the depth of water from precipitation. [14] |
| 2115 | Polar Chart | See chart. [14] |
| 2116 | Press Proof | A lithographed impression taken from among the first copies run on the press and used for checking purposes. Also called press pull. [14] |
| 2117 | Print: Blue | A nonreproducible blue image or outline usually printed photographically on paper. [14] |
| 2118 | Pseudorange | The time shift required to align (correlate) a replica of the gps code generated in the receiver with the received gps code, scaled into distance by the speed of light. This time shift is the difference between the time of signal reception (measured in the receiver time frame) and the time of emission (measured in the satellite time frame). [14] |
| 2119 | Qtg Station | A radio station which is prepared to provide qtg service, that is to say, to transmit upon request from a ship, a radio signal, the bearing of which can be taken by that ship. [14] |
| 2120 | Radar Chain | An arrangement of radar sets in a chain usually used for vessel traffic control. [14] |
| 2121 | Radar Chart | See chart. [14] |
| 2122 | Rain Shadow | The region on the leeside of a mountain where the precipitation is noticeably less than on the windward side. [1] |
| 2123 | Ratio Print | See print. [14] |
| 2124 | Reflectance | The ratio of light given off by an object to the amount of light striking the object, expressed as percentage. [14] |
| 2125 | Rift Valley | See median valley. [14] |
| 2126 | Ripple Mark | Undulating surface features of various shapes produced in unconsolidated sediments by wave or current action. [14] |
| 2127 | River Mouth | The exit or point of discharge of a river into the sea, a lake, or another river. [14] |
| 2128 | Running Fix | See fix. [14] |
| 2129 | Safety Aids | See aid to navigation. [14] |
| 2130 | Salinometer | Any device or instrument for determining salinity, especially one based on electrical conductivity methods. [14] |
| 2131 | Sea Channel | A continuously sloping elongated discrete depression commonly found in fans or abyssal plains and customarily bordered by levees on one or both sides. [14] |
| 2132 | Seismograph | An instrument that records the direction, intensity and time of earthquakes. [14] |
| 2133 | Selectivity | The degree of decrease in the response of a resonant device with departure from resonance. Selec-tivity determines the ability of a radio receiver to differentiate between signals of different carrier frequency. [14] |
| 2134 | Sexagesimal | An angular division whereby a circle is divided in 360 equal parts called degrees. A degree is divided in 60 minutes and one minute in 60 seconds. [14] |
| 2135 | Shade Glass | See shade. [14] |
| 2136 | Shadow Zone | A region into which very little sound energy penetrates. [14] |
| 2137 | Shelf Break | See shelf edge. [14] |
| 2138 | Shelf Cloud | A dense, arch-shaped, ominous-looking cloud that often forms along the leading edge of a thunderstorm's gust front, especially when stable air rises up and over cooler air at the surface. Also called an arcus cloud. [1] |
| 2139 | Signal: Fog | See fog signal. [14] |
| 2140 | Sky Compass | See compass. [14] |
| 2141 | Slide: Dark | A thin plate (usually metal or fibre, rigid or flexible) which, after insertion in a camera magazine, renders it light-tight. [14] |
| 2142 | Snow Grains | Precipitation in the form of very small, opaque grains of ice. The solid equivalent of drizzle. [1] |
| 2143 | Speed Scale | See scale. [14] |
| 2144 | Spoil Banks | Submerged accumulations of dumped material dredged from channels or harbors. [14] |
| 2145 | Squall Line | Fictitious moving line, sometimes of considerable extent, along which squall phenomena occur. [14] |
| 2146 | Steerageway | The condition wherein the ship has sufficient way on that it will respond to rudder movements to maintain desired course. [14] |
| 2147 | Stereometer | A measuring device comprising a micrometer movement by means of which the separation of two index marks can be changed to measure parallax difference on a stereoscopic pair of photographs. Also called parallax bar. [14] |
| 2148 | Stream: Ebb | See ebb stream. [14] |
| 2149 | Strong Gale | Wind with a speed between 41 and 47 knots (beaufort scale wind force 9). [14] |
| 2150 | Sun Compass | See compass. [14] |
| 2151 | Surface Map | A map that shows the distribution of sea-level pressure with isobars and weather phenomena. Also called a surface chart. [1] |
| 2152 | Survey Boat | A boat used for hydrographic surveys. [14] |
| 2153 | Survey Buoy | See buoy. [14] |
| 2154 | Survey Mark | An object placed at the site of a station to identify the surveyed location of that station. In particular, an object whose coordinates are used for control in a geodetic network. Also called marker, geodetic marker, and monument. [14] |
| 2155 | Survey: New | See resurvey. [14] |
| 2156 | Swirl Error | See error. [14] |
| 2157 | Tangent Arc | An arc of light tangent to a halo. It forms by refraction of light through ice crystals. [1] |
| 2158 | Terrigenous | (Adj.). Derived from the land. Applied to marine deposits, originating from the erosion of the land as opposed to pelagic deposits. [14] |
| 2159 | Texas Tower | A fixed tower mounted on the continental shelf or on a shoal, used to drill and operate gas or petroleum wells, and to provide a platform for aids to navigation and meteorological or oceanographic instrumentation. [14] |
| 2160 | Thermoprobe | A transducer used to measure temperature 'in situ' of ocean bottom sediments at depths beneath the bottom. Such measurements when combined with heat conductivity information provide a measurement of heat flow through the ocean bottom. [14] |
| 2161 | Tidal Basin | See basin. [14] |
| 2162 | Tidal Epoch | See phase lag. [14] |
| 2163 | Tidal Water | Any water the level of which changes periodically due to tidal action. See tidewater. [14] |
| 2164 | Tide Rip(S) | Small waves formed on the surface of water by the meeting of opposing tidal currents or by a tidal current crossing an irregular bottom. Vertical oscillation, rather than progressive waves, is charac-teristic of tide rips. [14] |
| 2165 | Tide Signal | See signal. [14] |
| 2166 | Tide: Earth | Periodic movement of the earth's crust caused by the tide-producing forces of the moon and sun. [14] |
| 2167 | Tide: Flood | See tide: rising. [14] |
| 2168 | Tide: Lunar | That part of the tide due solely to the tide-producing forces of the moon, as distinguished from that part caused by the forces of the sun. See tide: solar. [14] |
| 2169 | Tide: Mixed | The type of tide in which a diurnal wave produces large inequalities in heights and/or durations of successive high and/or low waters. This term applies to the tides intermediate to those predomi-nantly semidiurnal and those predominantly diurnal. [14] |
| 2170 | Tide: Slack | See slack water. [14] |
| 2171 | Tide: Solar | That part of the tide due solely to the tide-producing forces of the sun, as distinguished from that part caused by the forces of the moon. [14] |
| 2172 | Tide: Storm | See storm surge. [14] |
| 2173 | Time: Local | Time based upon the local meridian as reference, as contrasted with that based upon a zone meridian, or the meridian of Greenwich. Any time kept locally. [14] |
| 2174 | Time: Solar | Time based upon the rotation of the earth relative to the sun. See time: apparent solar, time: astronomical, time: civil, time: mean solar. [14] |
| 2175 | Torrid Zone | That part of the earth between the tropic of cancer and the tropic of Capricorn. Also called the tropics. [14] |
| 2176 | Track Chart | A chart showing recommended, required, or established tracks, and usually indicating turning points, courses, and distances. [14] |
| 2177 | Triangulate | The process of triangulation. [14] |
| 2178 | Trilaterate | The process of trilateration. [14] |
| 2179 | Ultrasonics | The science and technology relating to sound waves of frequencies above the audible range. [14] |
| 2180 | Upslope Fog | Fog formed as moist, stable air flows upward over a topographic barrier. [1] |
| 2181 | Vacuum Lead | A corer which makes use of hydrostatic pressure to force a tube into the bottom sediment. [14] |
| 2182 | Velocimeter | An instrument used for the 'in situ' measurement of the speed of sound in the sea and other natural waters. [14] |
| 2183 | Watch: Hack | A watch used for timing observations of celestial bodies regulating ship's clocks, etc. [14] |
| 2184 | Watch: Stop | A watch that can be started, stopped, and reset at will, to indicate elapsed time. [14] |
| 2185 | Water Front | Land at the end of a stream, harbor, etc. The part of a city or town on such land; wharf or dock area. [14] |
| 2186 | Watercourse | A stream of water, a river or a brook; also an artificial channel for the conveyance of water. [14] |
| 2187 | Wave Deltas | See washovers. [14] |
| 2188 | Wave: Short | A radio wave shorter than those of the standard broadcasting band. In oceanography, waves under conditions where the relative depth (water depth/wavelength) is greater than 0.5 and where the phase velocity is independent of water depth, but dependent upon wavelength. [14] |
| 2189 | Wave: Storm | A wind-generated sea surface wave of great height. See storm surge. [14] |
| 2190 | Wave: Tidal | The wave motion of the tides. In popular usage, any unusually high (and therefore destructive) water level along a shore. It usually refers to either a storm surge or tsunami. [14] |
| 2191 | International Commission For The Scientific Exploration Of The Mediterranean Sea (Icsem) | serves as liaison for research in Mediterranean laboratories; promotes international activities on behalf of countries bordering the Mediterranean. [14] |
| 2192 | LAT | Lowest astronomical tide (LAT); The lowest level astronomical tide that can be expected to occur under average meteorological conditions and under any combination of astronomical conditions. [24] |
| 2193 | HAT | Highest astronomical tide (HAT); The highest level astronomical tide that can be expected to occur under average meteorological conditions and under any combination of astronomical conditions. [24] |
| 2194 | Era | In geology, any of the main divisions of geological time. [14] |
| 2195 | Low | See depression. [14] |
| 2196 | Sea | The great body of salt water in general, as opposed to land; ocean. One of the smaller divisions of the oceans. The state of the surface of the ocean with regard to wave or swell, as a calm sea. See cross sea, head sea, beam sea, following sea, quartering sea, sugar loaf sea. [14] |
| 2197 | Surveying | Specifically, the science or art of making such measurements as are necessary to determine the relative position of points above, on, or beneath the surface of the earth, or to establish such points. Generally, the art of making a survey. [14] |
| 2198 | Aerial | See antenna. [14] |
| 2199 | Magnetic Field | The space in which a magnetic influence exists. [14] |
| 2200 | Satellite | A relatively small celestial body revolving around a planet. Name sometimes given to the fictitious bodies assumed in the harmonic analysis of tides. [14] |
| 2201 | Tidal Current | An alternating, horizontal movement of water associated with the rise and fall of the tide, these movements being caused by gravitational forces due to the relative motions of Moon, Sun, and Earth. [20] |
| 2202 | Sea Level | The height of the sea surface uninfluenced by wind waves and swell, which is frequently measured relative to a reference horizon. Observations of the sea level over a certain period are often evaluated to render minimum, maximum, and mean sea level. [14] |
| 2203 | Orientation | The act of establishing the correct relationship in direction with reference to the points of the compass. The state of being in correct relationship in direction with reference to the points of the compass. A map is in orientation when the map symbols are parallel with their corresponding ground features. A photograph is in orientation when it correctly presents the perspective view of the ground or when images on the photograph appear in the same direction from the point of observation as do the corresponding map symbols. See orientation of plane table, orientation of surveying instrument, orientation: photogrammetric. [14] |
| 2204 | Nodal Point | In optics, one of the two points on the optical axis of a lens (or a system of lenses) such that a ray emergent from the second point is parallel to the ray incident at the first. The first nodal point is referred to as the front nodal point or incident nodal point, and the second nodal point as the rear nodal point or emergent nodal point. An amphidromic point. In astronomy, a node. [14] |
| 2205 | Positioning | The process of determination of a position. [14] |
| 2206 | Oscillation | The variation, usually with time, of the magnitude of a quantity with respect to a specified reference when the magnitude is alternately greater and smaller than the reference. Half an oscillatory cycle, consisting of a fluctuation or vibration in one direction; half a vibration. [14] |
| 2207 | Spirit Level | See level. [14] |
| 2208 | Celestial Sphere | An imaginary sphere of infinite radius, concentric with the earth, on which celestial bodies are imagined to be projected. Also called celestial concave. [14] |
| 2209 | Magnetic Compass | See compass. [14] |
| 2210 | Oceanography | The study of the sea, embracing and integrating all knowledge pertaining to the sea's physical boundaries, the chemistry and physics of sea water, marine biology, and submarine geology. In strict usage oceanography is the description of the marine environment, whereas oceanology is the study of the oceans and related sciences. [14] |
| 2211 | Shallow Water | Commonly, water of such a depth that surface waves are noticeably affected by bottom topog-raphy. It is customary to consider water of depths less than half the surface wavelength as shallow water. [14] |
| 2212 | Water Bottle | A device for collecting water samples from varying depths. They are lowered in an 'open' state to the required depth and can be closed before being hauled up by means of a messenger. Water bottles can be operated in series that is with more than one bottle on the wire rope so that water samples can be taken at a number of depths on the same cast. Also called water specimen cup. [14] |
| 2213 | Nautical Chart | A chart specifically designed to meet the requirements of marine navigation, showing depths of water, nature of bottom, elevations, configuration and characteristics of coast, dangers and aids to navigation. May be a paper chart, electronic navigational chart (enc) or a raster navigational chart (rnc). Also called marine chart, hydrographic chart, or simply chart. - 2. (from solas chapter v) a special-purpose map or a specially compiled database from which a map is derived, that is issued officially by or on the authority of a government, authorized hydrographic office or other relevant government institution and is designed to meet the requirements of marine navigation. [14] |
| 2214 | Line Of Position | A line indicating a series of possible positions of a craft, determined by observation or measurement. Also called position line. See celestial line of position, circle of position, course line, electronic line of position, fix, hyperbolic line of position, latitude line, leading line, longitude line, retired line of position, sonic line of position, speed line, sumner line, surface of position, visual line of position. [14] |
| 2215 | Hydrographic Survey | See survey. [14] |
| 2216 | Transponder | A combined receiver and transmitter whose function is to transmit signals automatically when triggered by an interrogator. See transceiver. [14] |
| 2217 | Level: Spirit | A small closed vessel of glass (vial), having the inside surface of its upper part curved in form; the vessel is nearly filled with a fluid of low viscosity (alcohol or ether), enough free space being left for the formation of a bubble of air and gas, which will always assume a position at the top of the vessel. There are two types of spirit levels used in surveying: one has the curved surface spherical in form, producing a bubble of circular outline; and is properly called a circular level (also universal level or bull's eye level). The other and much more generally used type has a vessel in the form of circular tube, the longitudinal axis of which is also circular in form. It is the type usually referred to when the term 'spirit level' is used. The spirit level is also called spirit bubble or sensitive bubble. [14] |
| 2218 | Line Of Sight | The straight line between two points. This line is in the direction of a great circle, but does not follow the curvature of the earth. See also collimation: line of. [14] |
| 2219 | Nautical Mile | A unit of length used principally in navigation. See international nautical mile. [14] |
| 2220 | Displacement | In radiolocation, the half of the band of uncertainty having as its center line an electronic line of position. In photogrammetry, any shift in the position of an image on a photograph which does not alter the perspective characteristics of the photograph (i.e. Shift due to tilt of the photograph, scale change in the photograph, and relief of the objects photographed). [14] |
| 2221 | Echo Sounding | Determination of the depth of water by measuring the time interval between emission of a sonic or ultrasonic signal and return of its echo from the bottom. Also called acoustic sounding. See also echo sounder. [14] |
| 2222 | Dead Reckoning | A method of navigation utilizing only the speed and heading of the craft, without reference to external aids. In air navigation, the best estimate of course and speed over the ground is used, i.e., dead reckoning incorporates wind vector. [14] |
| 2223 | Vertical Plane | See plane. [14] |
| 2224 | Angular Distance | The angular difference between two directions, numerically equal to the angle between two lines extending in the given directions. The arc of the great circle joining two points, expressed in angular units. [14] |
| 2225 | Focal Length | The distance from the rear nodal point of a lens to the focal plane for an object at infinity. The distance from the surface of a mirror to its focus. Also called focal distance. [14] |
| 2226 | Control Point | A point on the ground whose position (horizontal and vertical) is used as a base for a dependent survey. Also referred to as control station.- 2. In photogrammetry, any point in a horizontal and vertical control system that is identified on a photograph and used for correlating the data shown on that photograph. More specific terms are photo-control point, picture control point and ground control point. [14] |
| 2227 | Current Meter | An instrument for the measurement of either speed alone or of both direction and speed of a current. See current pole, Ekman current meter, price-gurley current meter, roberts radio current meter, swallow float, savonius rotor current meter, wollaston current meter. [14] |
| 2228 | Establishment | The interval of time between the transit (upper or lower) of the moon and the next high water at a place. The average establishment at the time of full or new moon is called vulgar or common establishment, or high water full and change. Also called high water lunitidal interval, or establishment of the port. See lunitidal interval. [14] |
| 2229 | Sounding Line | A line of sounding. A lead line. [14] |
| 2230 | Celestial Pole | See pole. [14] |
| 2231 | Line Of Sounding | A series of soundings along a predetermined line, and at stated intervals, when surveying. Also referred to as sounding line. See check lines, cross lines, cross-section lines, inter line, split line, starred lines, track line of sounding, systems of sounding lines. [14] |
| 2232 | Tropical Cyclone | Cyclone of tropical origin of small diameter (some hundreds of kilometers). It is characterized by violent wind and torrential rain. Sometimes accompanied by a thunderstorm. [14] |
| 2233 | Water Sample | A portion of water brought up from a certain depth to determine its composition, or physical properties viz: temperature, salinity and density. [14] |
| 2234 | Magnetic Pole | Either of the two places on the surface of the earth where the magnetic dip is 90°, that in the northern hemisphere being designated north magnetic pole, and that in the southern hemisphere being designated south magnetic pole. The magnetic poles are not fixed and do not coincide with the geographical poles. Either of those two points of a magnet where the magnetic force is greatest. [14] |
| 2235 | Map Projection | See projection. [14] |
| 2236 | Mean Solar Day | See day: solar. [14] |
| 2237 | Principal Line | In photogrammetry, the trace of the principal plane upon the photograph, (e.g., the line through the principal point and the photograph nadir). [14] |
| 2238 | Vertical Circle | See circle. [14] |
| 2239 | Sextant Altitude | See under altitude. [14] |
| 2240 | Weather Forecast | Statement of the expected meteorological conditions for a specified period, and for specified area or portion of air space. [14] |
| 2241 | Relative Position | See position. [14] |
| 2242 | Perspective Centre | The point of origin or termination of bundles of perspective rays. The two such points usually associated with a survey photograph are the interior perspective center and the exterior perspective center. In a perfect lens-camera system, perspective rays from the interior perspective center to the photographic images enclose the same angles as the corresponding rays from the exterior perspective center to the objects photographed. In a lens having distortion this is true only for a particular zone of the photograph. In a perfectly adjusted lens-camera system the exterior and interior perspective centers correspond, respectively, to the front and rear nodal points of the camera lens. [14] |
| 2243 | Survey Sheet | See hydrographic survey sheet. [14] |
| 2244 | Levelling Rod | A straight rod or bar, designed for use in measuring a vertical distance between a point on the ground and the line of collimation of a levelling instrument which has been adjusted to horizontal position. Also called levelling staff. [14] |
| 2245 | Scale: Natural | The ratio between the linear dimensions of a chart, drawing, etc., and the actual linear dimensions represented, expressed as a proportion. Occasionally called representative fraction, fractional scale or numerical scale. [14] |
| 2246 | Horizontal Axis | See axis. [14] |
| 2247 | Principal Point | In photogrammetry, the foot of the perpendicular from the interior perspective center to the plane of the photograph (i.e. The foot of the photograph perpendicular). [14] |
| 2248 | Territorial Sea | A belt of water of a defined breadth but not exceeding 12 nautical miles measured seaward from the territorial sea baseline. [14] |
| 2249 | Zenith Distance | The vertical angle between the zenith and the object which is observed or defined. Zenith distance is the complement of the altitude. See zenith distance: double. [14] |
| 2250 | Meridian Transit | The apparent passage of a celestial body across a celestial meridian. Upper or superior transit is the passage across the upper branch of the celestial meridian. Lower or inferior transit is the passage across the lower branch. The lower transit may take place either above the horizon as is the case of circumpolar celestial bodies, or across that branch of the meridian lying below the observer's horizon. Also called transit, meridian passage, culmination. [14] |
| 2251 | Coordinate System | A fixed system of lines used to define the position of a point, line, or plane. [14] |
| 2252 | Pressure Gradient | Vector, perpendicular to the isobaric line or surface, directed towards low pressure and of intensity equal to the rate of variation of the pressure with distance. Also called barometric gradient. [14] |
| 2253 | Sextant: Sounding | (British terminology). A simplified and more robustly constructed version of the marine sextant intended primarily for use in hydrographic survey. It has no shades, a wide angle low magnification telescope and is generally graduated in minutes of arc. It may be fitted with either a vernier or a micrometer reading device. Both mirrors are silvered all over to enable angles up to 180° to be measured. Some sounding sextants have a 90° prism attachment which reflects the normal direct line of sight 90° to the left. Called surveying sextant, or hydrographic sextant in US Terminology. [14] |
| 2254 | Primary Great Circle | A great circle used as the origin of measurement of a coordinate; particularly such a circle 90° from the poles of a system of spherical coordinates, as the equator. Also called primary circle, fundamental circle. [14] |
| 2255 | Water Column | A vertical continuum of water from sea surface to sea-bed. [14] |
| 2256 | Depth Contour | See depth curve. [14] |
| 2257 | Ground Survey | See survey. [14] |
| 2258 | Level Surface | A surface which, at every point, is perpendicular to the direction of gravity. A level surface is an equipotential surface. The geoid or, in general, any surface parallel to it, is a level surface. If changes in elevation due to tides, winds, etc. Are neglected, the surface of the sea is a level surface. A level surface is not a plane surface, but it is sometimes so regarded in surveys of limited areas. [14] |
| 2259 | Range Of Tide | The difference in height between consecutive high and low tides at a place. Also called tidal (or tide) range. [14] |
| 2260 | Coriolis Force | Composite centrifugal force, due to the rotation of the earth, which acts on moving particles, whose motion is considered relative to that of the earth. [14] |
| 2261 | Height Of Tide | The vertical distance from the chart datum to the level of the water at any time. [14] |
| 2262 | Mercator Chart | See chart. [14] |
| 2263 | Objective Lens | In telescopes and microscopes, the optical component which receives light from the object and forms the first or primary image. In a camera, the image formed by the objective lens is the final image. In a telescope or microscope used visually, the image formed by the objective lens is magnified by the eyepiece. Also called objective or object-glass. [14] |
| 2264 | Reconnaissance | In surveying, a general examination or survey of the main features, or certain specific features, of a region, usually as a preliminary to a more detailed survey. An examination of an area to gain specific information, as the weather conditions, extent and nature of ice, etc. [14] |
| 2265 | Sounding Datum | See datum. [14] |
| 2266 | Magnetic Needle | A small, slender magnetized bar which tends to align itself with magnetic lines of force. [14] |
| 2267 | Navigation Mark | An artificial or natural object of easily recognizable shape or colour, or both, situated in such a position that it may be identified on a chart or related to a known navigational instruction. Alternative term for visual aid to navigation. Includes both buoys and beacons (fixed artificial navigation mark). [14] |
| 2268 | Collimation Axis | The line through the optical center of the objective lens perpendicular to the axis of rotation of the telescope. Also called axis of collimation. [14] |
| 2269 | Error Of Closure | The amount by which a quantity obtained by a series of related measurements differs from the true or fixed value of the same quantity. Also called closing error. [14] |
| 2270 | Geodetic Equator | See equator. [14] |
| 2271 | Horizontal Plane | See plane. [14] |
| 2272 | Vertical Control | See control. [14] |
| 2273 | Eccentric Station | A survey point over which an instrument is centered and observations are made, which is not in the same vertical line with the station it represents, and to which the observations will be reduced before being combined with observations at other stations. Also called false station or satellite station. See eccentric reduction. [14] |
| 2274 | Greenhouse Effect | The warming of an atmosphere by its absorbing and emitting infrared radiation while allowing shortwave radiation to pass on through. The gases mainly responsible for the earth's atmospheric greenhouse effect are water vapor and carbon dioxide. See atmospheric greenhouse effect. [1] |
| 2275 | Celestial Meridian | See meridian. [14] |
| 2276 | Current: Reversing | A tidal current which flows alternately in approximately opposite directions, with slack water at each reversal. Such currents occur principally in areas where motion is largely restricted to relatively narrow channels. Also called rectilinear current or rectilinear stream. [14] |
| 2277 | Oblique Photograph | See photograph. [14] |
| 2278 | Harmonic Constituent | One of the harmonic elements in a mathematical expression for the tide-producing force, and in corresponding formulae for the tide or tidal current. Each constituent represents a periodic change or variation in the relative positions of the earth, sun and moon. Also called tidal constituent or component. [14] |
| 2279 | True Horizon | See horizon. [14] |
| 2280 | Acoustic Wave | See wave: sound. [14] |
| 2281 | Apparent Time | See time: apparent solar. [14] |
| 2282 | Earth'S Crust | See crust. [14] |
| 2283 | Fixed Station | A radiolocation station which is situated in one particular spot throughout the period of its operation. As opposed to mobile station. Also called shore station.in oceanography, a platform from which repeated observations are taken. These include coastal and island stations, light vessels, weather ships, automatic floating stations and ice islands. Also called fixed platform. [14] |
| 2284 | Geodesic Line | The shortest line on a mathematically derived surface, between two points on that surface. A geodesic line on a reference spheroid is called a geodetic line. Also termed a geodesic. [14] |
| 2285 | Least Squares | A method of adjusting observations in which the sum of the squares of all the deviations or residuals derived in fitting the observations to a mathematical model, is made a minimum. Least squares have also been designated as minimum squares. [14] |
| 2286 | Nansen Bottle | A device used by oceanographers to obtain subsurface samples of sea water. The bottle is lowered by wire; its valves are open at both ends. It is then closed 'in situ' by allowing a weight (called a messenger) to slide down the wire and strike the reversing mechanism. This causes the bottle to turn upside down, closing the valves and reversing the reversing thermometers which are mounted in a special thermometer case on it. If, as is usually done, a series of bottles is lowered, then the reversal of each bottle releases another messenger to actuate the bottle beneath it. [14] |
| 2287 | Nodical Month | See month. [14] |
| 2288 | Ocean Current | See current. [14] |
| 2289 | Radial Centre | In photogrammetry, the selected point on a photograph from which radials (directions) to various image points are drawn or measured (i.e., the origin of radials). The radial center is either the principal point, the nadir point, the isocenter, or a substitute center. [14] |
| 2290 | Radio Station | A place equipped to transmit radio waves. Such a station may be either stationary or mobile, and may also be provided with a radio receiver. In British terminology, also called w/t station. [14] |
| 2291 | Radius Vector | A straight line connecting a fixed reference point or center with a second point, which may be moving. In astronomy, the expression is usually used to refer to the straight line connecting a cele-stial body with another which revolves around it, as a radius vector of the earth and moon. See coordinates: plane polar and coordinates: polar. [14] |
| 2292 | Stand Of Tide | The condition at high tide or low tide when there is no change in the height of the water. It may be called high water stand if it occurs at the time of high tide, and low water stand if it occurs at low tide. Also called stand. [14] |
| 2293 | Station: Tide | A place where tidal observations are obtained. It is a primary tide station when continuous observations are available for a sufficient number of years to determine the characteristic tide features for the locality. A secondary tide station is operated during a short period of time to obtain data for a specific purpose. [14] |
| 2294 | Swinging Ship | The process of placing a vessel on various headings and comparing magnetic compass readings with the corresponding magnetic directions, to determine deviation. This usually follows compass compensation (or adjustment), and is done to obtain information for making a deviation table. Also called compass calibration, or calibration of compass. See compensation of magnetic compass. [14] |
| 2295 | Air Navigation | See navigation. [14] |
| 2296 | Diurnal Motion | The apparent daily motion of a celestial body. [14] |
| 2297 | Frequency Band | See band of frequency. [14] |
| 2298 | Geodetic Datum | See datum. [14] |
| 2299 | Gradient Tints | See hypsometric tints. [14] |
| 2300 | Ground Control | See control. [14] |
| 2301 | On The Quarter | Bearing approximately 135° relative (on the starboard quarter) or 225° relative (on the port quarter). The expression is often used loosely for broad on the quarter, or bearing exactly 135° or 225° relative. See also broad on the quarter. [14] |
| 2302 | Personal Error | See error. [14] |
| 2303 | Prime Vertical | See prime vertical circle. [14] |
| 2304 | Time: Apparent | See time: apparent solar. [14] |
| 2305 | Wind Direction | The direction from which the wind is blowing. [1] |
| 2306 | Control Station | see control point . [14] |
| 2307 | Lens Distortion | See distortion. [14] |
| 2308 | Modulating Wave | See wave. [14] |
| 2309 | Parhelic Circle | Photometeor of the halo family, consisting of a white, horizontal circle, situated at the same angular height as the sun. [14] |
| 2310 | Plane Surveying | See surveying. [14] |
| 2311 | Principal Plane | In photogrammetry, the vertical plane through the internal perspective center containing the photograph perpendicular of a tilted photograph. [14] |
| 2312 | Relative Motion | Motion of one object or body relative to another. The expression is usually used in connection with problems involving motion of one craft, torpedo, or missile relative to another, the direction of such motion being called direction of relative movement, and the speed of such motion being called speed of relative movement or relative speed. Usually called apparent motion when applied to the change of position of a celestial body as observed from the earth. Also called relative movement. [14] |
| 2313 | Station Pointer | (British terminology). A metal instrument with three legs, a circle graduated in degrees and 1/2 degrees, and a vernier or micrometer for setting the angles. See also protractor: three arm. [14] |
| 2314 | Axis Of Homology | In photogrammetry, the intersection of the plane of the photograph with the horizontal plane of the map or the plane of reference of the ground. Corresponding lines in the photograph and map planes intersect on the axis of homology. Also called the axis of perspective, or map parallel. [14] |
| 2315 | Central Meridian | See meridian: initial. [14] |
| 2316 | Compass: Hanging | A compass having its binnacle overhead and its graduated card facing downward. Also referred to as overhead compass, or inverted compass. [14] |
| 2317 | Direction Finder | See radio direction finder. [14] |
| 2318 | Mean Water Level | The average surface level of a body of water. [14] |
| 2319 | Oscillatory Wave | See wave. [14] |
| 2320 | Parallax: Annual | The angle subtended at a celestial body by the radius of earth's orbit. Also called heliocentric parallax, or stellar parallax. [14] |
| 2321 | Aid To Navigation | A visual, acoustical, or radio device, external to a ship, designed to assist in determining a safe course or a vessel ™s position, or to warn of dangers and/or obstructions. Aids to navigation usually include buoys, beacons, fog signals, lights, radio beacons, leading marks, radio position fixing systems and gnss which are chart-related and assist safe navigation. [14] |
| 2322 | Bottom: Nature Of | The feature of the bottom including the material of which it is composed and its physical characteristics. Also called character (or characteristics) of the bottom, or quality of the bottom. [14] |
| 2323 | Geodetic Meridian | See meridian. [14] |
| 2324 | Horizontal Circle | See circle. [14] |
| 2325 | Parallactic Angle | That angle of the astronomical triangle at the celestial body; the angle between a body's hour circle and its vertical circle. Also called position angle.in photogrammetry, the angle subtended by the eye of the observer at the object viewed. Also called angle of convergence or angular parallax. [14] |
| 2326 | Personal Equation | The time interval between the sensory perception of a phenomenon and the motor reaction thereto. Personal equation may be either positive or negative, as an observer may anticipate the occurrence of an event, or wait until he actually sees it occur before making a record. This is a syste-matic error, treated as of the constant type. It is a personal error, for which the term personal equation is reserved. It is of special significance in observations of time, made to determine chronometer correction. [14] |
| 2327 | Reference Station | See station. [14] |
| 2328 | Stereoscopic Pair | In photogrammetry, two photographs of the same area taken from different air stations so as to afford stereoscopic vision. Frequently called a stereopair. [14] |
| 2329 | Altitude: Apparent | The sextant altitude of a celestial body corrected for index error, dip (height of eye), and (for sun or moon only) semidiameter. Also called rectified altitude. [14] |
| 2330 | Angle Of Incidence | The angle between the line of motion of a ray and the perpendicular to a surface at the point of impingement. [14] |
| 2331 | Geodetic Longitude | See longitude. [14] |
| 2332 | Greenwich Meridian | See meridian. [14] |
| 2333 | Low Water Interval | See lunitidal interval. [14] |
| 2334 | Phototriangulation | The process for the extension of horizontal and/or vertical control whereby the measurements of angles and/or distances on overlapping photographs are related into a spatial solution using the perspective principles of the photographs. Generally, this process involves using aerial photographs, and is called aero triangulation, aerial triangulation, or photogrammetric extension. [14] |
| 2335 | Temporal Variation | See magnetic temporal variation. [14] |
| 2336 | Aberration Of Light | Astronomy, the apparent displacement in position of a heavenly body caused by the combination of the velocity of light and that of an observer on the surface of the earth. Aberration of light due to the rotation of the earth on its axis is termeddiurnal aberration. That due to the revolution of the earth around the sun is termedannual aberration. In optics, failure of an optical system to bring all light rays received from a point object to a single image point or to a prescribed geometric position. Spherical aberration is caused by rays from various zones of a lens or mirror coming to focus at different distances from the lens or mirror. Chromatic aberration(orchromatism) is due to the differences in refraction of the coloured rays of the spectrum; those of each colour having a different focus. [14] |
| 2337 | Closure Of Triangle | See error of closure of triangle. [14] |
| 2338 | Radial Triangulation | The aero triangulation procedure, either graphical or analytical, in which directions from the radial center, or approximate radial center, of each overlapping photograph are used for horizontal-control extension by the successive intersection and resection of these direction lines. A radial triangulation also is correctly called a radial plot or a minor-control plot. If made by analytical methods, it is called an analytical radial triangulation. A radial triangulation is assumed to be graphical unless prefixed by the word analytical. [14] |
| 2339 | Tape: Sag Correction | The difference between the effective length of a tape (or part of a tape) when supported continuously throughout its length and when supported at a limited number of independent points. Also called catenary correction. [14] |
| 2340 | Electronic Navigation | See navigation. [14] |
| 2341 | Spheroid Of Reference | See reference spheroid. [14] |
| 2342 | Flattening Of The Earth | The ratio of the difference between the equatorial and polar radii of the earth (major and minor semi-axes of the spheroid) and its equatorial radius (major semi-axis). The flattening of the earth is the ellipticity of the spheroid. Also called compression. [14] |
| 2343 | Weather Ship | See ocean station vessel. [14] |
| 2344 | Aerial Camera | See camera. [14] |
| 2345 | Aerial Survey | See survey. [14] |
| 2346 | Annual Change | See magnetic annual change. [14] |
| 2347 | Azimuth Angle | Azimuth measured from 0° at the north or south reference direction clockwise or counter-clockwise through 90° or 180°. It is labelled with the reference direction as a prefix and the direction of measurement from the reference direction as a suffix. [14] |
| 2348 | Azimuth: Back | An azimuth 180° from a given azimuth. In geodesy, the direction of the line ba as distinguished from the forward azimuth ab. The two differ by 180° plus the amount of convergence of the meridians between points a and b. Also called reverse azimuth. See azimuth: geodetic. [14] |
| 2349 | Bottom Sample | A portion of the sea bottom material brought to the surface for examination. See also core. [14] |
| 2350 | Drift Current | See current. [14] |
| 2351 | Floating Mark | In photogrammetry, a mark seen as occupying a position in the three-dimensional space formed by the stereoscopic fusion of a pair of photographs and used as a reference mark in examining or measuring the stereoscopic model. [14] |
| 2352 | Heavenly Body | See celestial body. [14] |
| 2353 | Horizon Glass | That glass of a marine sextant, attached to the frame, through which the horizon is observed. That half of this glass nearer the frame is silvered to form the horizon mirror for reflecting the image of a celestial body; the other half is clear. [14] |
| 2354 | Initial Point | The origin of a system in the rectangular system of surveys of which a principal meridian and a base line constitute the axes for a given area. Also called fundamental point. [14] |
| 2355 | Inner Harbour | See under harbor. [14] |
| 2356 | Leading Marks | (British terminology). Aids to navigation or other indicators so located as to indicate the path to be followed. Leading marks identify a leading line when they are in transit. See also range. [14] |
| 2357 | Luminous Flux | See flux. [14] |
| 2358 | Magnetization | The degree to which a body is magnetized. The magnetic moment per unit volume. Also called intensity of magnetization. [14] |
| 2359 | Plane Sailing | See sailing. [14] |
| 2360 | Position Line | See line of position. [14] |
| 2361 | Radiolocation | Determination of position or of a line of position by means of radio equipment. See navigation: electronic. [14] |
| 2362 | Rectification | The process of projecting a tilted or oblique photograph onto an horizontal reference plane, the angular relationship between the photograph and the plane being determined by ground methods. [14] |
| 2363 | Regular Error | See error: systematic. [14] |
| 2364 | Sidereal Time | See time. [14] |
| 2365 | Standing Wave | See wave. [14] |
| 2366 | Survey Signal | See signal. [14] |
| 2367 | Tide: Diurnal | A tide in which the tidal cycle consists of one high water and one low water each tidal day. In British terminology also called single day tide. [14] |
| 2368 | Tilting Level | See levelling instrument: tilting level. [14] |
| 2369 | Tropical Year | See year. [14] |
| 2370 | True Altitude | See altitude. [14] |
| 2371 | Turning Point | In levelling, a point on which both a minus sight (foresight) and a plus sight (backsight) are taken on a line of direct levelling. In topographic surveys, any point on which the rod is held while the instrument (plane table) is moved to another station. In a traverse, any point of junction of two legs. Also called traverse point. [14] |
| 2372 | Valley Breeze | A local wind system of a mountain valley that blows downhill (mountain breeze) at night and uphill (valley breeze) during the day. See mountain breeze. [1] |
| 2373 | Wave Spectrum | In ocean wave studies, a graph showing the distribution of wave heights with respect to frequency in a wave record. [14] |
| 2374 | Wind Spectrum | Measure of the variance associated with the fluctuating wind speed per unit frequency band. NOTE 1 The wind spectrum is an expression of the dynamic properties of the wind (turbulence). It reflects the fluctuations about and in the same direction as a certain mean wind speed, usually the 1 h sustained wind speed. There is hence no direction variable associated with the wind spectrum within this document. NOTE 2 As the sustained wind speed varies with elevation, the wind spectrum is a function of elevation. [15] |
| 2375 | Bearing: Sonic | A bearing determined by measuring the direction from which a sound wave is coming. Also called acoustic bearing. [14] |
| 2376 | Climate Change | A change in the long-term statistical average of weather elements such as temperature or precipitation sustained over several decades or longer. Climate change is also called climatic change. [1] |
| 2377 | Current Tables | Tables listing predictions of the times and speeds of tidal currents at various places, and other pertinent information. Also called tidal current tables. [14] |
| 2378 | Land Territory | Continental or insular land masses that are above water at high tide. [14] |
| 2379 | Low Water Line | See low water mark. [14] |
| 2380 | Magnetic North | See north. [14] |
| 2381 | Optical Centre | The point of intersection of lines which represent within the lens those rays whose emergent directions are parallel to their respective incident directions. This point lies on the optical axis. [14] |
| 2382 | Optical System | A series of lenses, apertures, prisms, mirrors, etc., so arranged as to perform a definite optical function. [14] |
| 2383 | Phantom Bottom | A false bottom indicated by an echo sounder, some distance above the actual bottom. Such an indication, quite common in the deeper parts of the ocean, is due to large quantities of small organisms. Also called deep scattering layer (DSL) or false bottom. [14] |
| 2384 | Plotting Sheet | A blank chart, usually on the Mercator projection, showing only the graticule and a compass rose, so that the plotting sheet can be used for any longitude. In hydrographic surveying, a working sheet on which the main stations of the survey are plotted. It forms the framework of the survey and provides the basis for accurately locating and plotting all the detail of the survey. See also lattice. [14] |
| 2385 | Radar: Primary | Radar which transmits a signal and receives the incident energy reflected from an object to detect the object in contrast to secondary radar which receives pulses from a transponder triggered by pulses transmitted from the radar. [14] |
| 2386 | Reference Line | Any line which can serve as a reference or base for the measurement of other quantities. Also called datum line. [14] |
| 2387 | Secular Change | An increase or decrease of intensity and/or change of direction of the total magnetic field over a period of many years. [14] |
| 2388 | Sound Pressure | See pressure. [14] |
| 2389 | Sound Velocity | The rate of motion at which sound energy moves through a medium. The velocity of sound in sea water is a function of temperature, salinity, and the changes in pressure associated with changes in depth. An increase in any of these factors tends to increase the velocity. [14] |
| 2390 | Tropical Storm | Organized thunderstorms with a cyclonic wind circulation between 35 and 64 knots. [1] |
| 2391 | Vernal Equinox | The equinox at which the sun approaches the northern hemisphere and passes directly over the equator. Occurs around march 20. [1] |
| 2392 | Year: Tropical | The period of one revolution of the earth around the sun, with respect to the vernal equinox. Because of precession of the equinoxes, this is not 360° with respect to the stars, but 50".3 less. A tropical year is about 20 minutes shorter than a sidereal year, averaging 365 days, 5 hours, 48 minutes, and 46 seconds in 1900 and is decreasing at the rate of 0.00530 second annually. Also called astronomical, equinoctial, natural, or solar year. [14] |
| 2393 | Bouguer Anomaly | A difference between an observed value of gravity and a theoretical value at the point of observation, which has been corrected for the effect of the topography and elevation only, the topography being considered as resting on a plane of indefinite extent. [14] |
| 2394 | Cardinal Points | The four points of the horizon at the intersections of the horizon with the meridian and the prime vertical; the north, south, east and west points. [14] |
| 2395 | Chart: Gnomonic | A chart on the gnomonic projection. Also called great circle chart. [14] |
| 2396 | Chart: Nautical | A chart specifically designed to meet the requirements of marine navigation, showing depths of water, nature of bottom, elevations, configuration and characteristics of coast, dangers and aids to navigation. Also called marine chart, hydrographic chart, or simply chart. [14] |
| 2397 | Compass: Liquid | A magnetic compass having a bowl completely filled with liquid in order to damp the swinging of the card. Sometimes called spirit compass, or wet compass. [14] |
| 2398 | Coordinate Axes | See coordinates: plane rectangular. [14] |
| 2399 | Current Station | The geographic location at which current observations are conducted. Also, the facilities used to make current observations. These may include a buoy, ground tackle, current meters, recording mechanism, and radio transmitter. See control current station and subordinate current station. [14] |
| 2400 | Data Processing | Any operation carried out with data usually with the help of a computer. [14] |
| 2401 | Error: Standard | The square root of the arithmetic mean of squared deviations from the mean. Also called standard deviation, when the deviations do not represent errors, or root mean square error. [14] |
| 2402 | Flight Altitude | See altitude. [14] |
| 2403 | Gust Wind Speed | Maximum value of the wind speed of a gust averaged over a short (3 s to 60 s) specified duration within a longer (1 min to 1 h) specified duration. NOTE 1 For design purposes, the specified duration depends on the dimensions and natural period of the (part of the) structure being designed such that the structure is designed for the most onerous conditions; thus, a small part of a structure is designed for a shorter gust wind speed duration (and hence a higher gust wind speed) than a larger (part of a) structure. NOTE 2 In practice, for design purposes, the gust wind speeds for different durations (e.g. 3 s, 5 s, 15 s, 60 s) are derived from the wind spectrum. [15] |
| 2404 | High Water Line | See high water mark. [14] |
| 2405 | Mean Solar Time | See time. [14] |
| 2406 | Navigation: Air | The navigation of aircraft. Occasionally called aerial navigation or navigation. See navigation: surface. [14] |
| 2407 | Oblate Spheroid | See spheroid. [14] |
| 2408 | Orthophotograph | A photographic copy, prepared from a perspective photograph, in which the displacements of images due to tilt and relief have been removed. [14] |
| 2409 | Point Of Origin | See coordinates: origin of. [14] |
| 2410 | Pole: Celestial | Either of the two points of intersection of the celestial sphere and the extended axis of the earth, labelled n or s to indicate either the north celestial pole or the south celestial pole. [14] |
| 2411 | Reference Level | See datum: chart and datum: vertical control. [14] |
| 2412 | Repetition Rate | The rate at which recurrent signals are transmitted. Also called recurrence rate. [14] |
| 2413 | Scatter Diagram | Joint probability of two or more (metocean) parameters. NOTE A scatter diagram is especially used with wave parameters in the metocean context. The wave scatter diagram is commonly understood to be the probability of the joint occurrence of the significant wave height (Hs) and a representative period (Tz or Tp). [15] |
| 2414 | Side Scan Sonar | A form of active sonar in which fixed acoustic beams are directed into the water perpendicularly to the direction of travel to scan the bottom and generate a record of the bottom configuration. [14] |
| 2415 | Synodical Month | See month. [14] |
| 2416 | Time: Greenwich | Time based upon the Greenwich meridian as reference. [14] |
| 2417 | Topographic Map | See map. [14] |
| 2418 | Transit Passage | In straits used for international navigation, all ships and aircraft enjoy the unimpeded right of transit passage. This means the freedom of navigation and overflight solely for the purpose of continuous and expeditious transit of the strait between one part of the high seas or an exclusive economic zone and another part of the high seas or an exclusive economic zone. See also innocent passage. [14] |
| 2419 | Vectorial Angle | See coordinates: plane polar. [14] |
| 2420 | Wire Drag Sweep | See survey: wire drag. [14] |
| 2421 | Altimeter: Radio | Any instrument used for determining an aircraft's flight altitude by the measurement of time intervals between the emission and return of electromagnetic pulses. Also called pulse radio altimeter or radar altimeter. See altitude: flight. [14] |
| 2422 | Annual Variation | See magnetic annual variation. [14] |
| 2423 | Apparent Horizon | See horizon. [14] |
| 2424 | Differential Gps | Differential gps is implemented by placing a gps monitor receiver at a precisely known location. Instead of computing a navigation fix, the monitor determines the range error to every gps satellite it can track. These ranging errors are then transmitted to local users where they are applied as corrections before computing the navigation result. [14] |
| 2425 | Eccentric Signal | A signal which is not in the same vertical line with the station it represents. [14] |
| 2426 | Equilibrium Tide | See tide. [14] |
| 2427 | Greenhouse Gases | Gases in the earth's atmosphere, such as water vapor and carbon dioxide, that allow much of the sunlight to pass through but are strong absorbers of infrared energy emitted by the earth and the atmosphere. Other greenhouse gases include methane, nitrous oxide, fluorocarbons, and ozone. [1] |
| 2428 | Magnetic Element | Variation, dip, or magnetic intensity. [14] |
| 2429 | Micrometer Screw | A finely threaded screw of definite pitch, with a head graduated to show how much the screw has been moved in or out; used in micrometers. [14] |
| 2430 | Radio Navigation | See navigation: electronic. [14] |
| 2431 | Rear Nodal Point | See nodal point. [14] |
| 2432 | Semidiurnal Tide | See tide. [14] |
| 2433 | Spring Low Water | See mean low water springs. [14] |
| 2434 | Systematic Error | See error. [14] |
| 2435 | Weather Analysis | Operation of studying the general state of the atmosphere over a region, with respect to synoptic charts. Also called synoptic analysis. [14] |
| 2436 | Aerotriangulation | See phototriangulation. [14] |
| 2437 | Bathymetric Chart | See chart. [14] |
| 2438 | Celestial Horizon | See horizon. [14] |
| 2439 | Centre Of Gravity | See gravity. [14] |
| 2440 | Geodetic Latitude | See latitude. [14] |
| 2441 | Geomagnetic Field | The magnetic field of the earth. Also called terrestrial magnetic field or earth's magnetic field. [14] |
| 2442 | Marine Navigation | See navigation. [14] |
| 2443 | Navigation: Sonic | Avigation by means of sound waves whether or not they are within the audible range. Also called acoustic navigation. [14] |
| 2444 | Parallax: Diurnal | The difference in the apparent direction or position of a celestial body as observed from the center of the earth and a point on its surface. This varies with the body's altitude and distance from the earth. Also called geocentric parallax. [14] |
| 2445 | Stability: Static | State of hydrostatic equilibrium of the atmosphere in which a particle of air moved from its initial level undergoes a hydrostatic force which tends to restore it to this level. Also called hydrostatic stability. [14] |
| 2446 | Strip Coordinates | See coordinates. [14] |
| 2447 | Telecommunication | Any transmission, emission, or reception of signs, signals, writing, images and sounds or intelligence of any nature by wire, radio, visual or other electromagnetic systems. [14] |
| 2448 | Triangulation Net | Arcs of triangulation, sometimes with lines of traverse, connected together to form a system of loops or circuits extending over an area. Sometimes called tie net when used to tie small islands together. Also called traverse net or survey net. [14] |
| 2449 | Aerial Photography | See photography. [14] |
| 2450 | Circle Of Latitude | A great circle of the celestial sphere through the ecliptic poles, and hence perpendicular to the plane of the ecliptic. [14] |
| 2451 | Condition Equation | See equation. [14] |
| 2452 | Continental Margin | The zone, generally consisting of shelf, slope and continental rise, separating the continent from the abyssal plain or deep sea floor. [14] |
| 2453 | Dry Adiabatic Rate | The rate of change of temperature in a rising or descending unsaturated air parcel. The rate of adiabatic cooling or warming is about 10°c per 1000 m (5.5°f per 1000 ft). [1] |
| 2454 | Hayford'S Spheroid | The spheroid based upon an investigation made in 1909 by hayford, a geodesist of US Coast & geodetic survey, using the large triangulation net then existing in the US A., and taking into account the inequal density of the earth's crust. The geodetic and geophysical union (now the international union of geodesy and geophysics) adopted in 1924 the hayford's spheroid (with some slight modifications) as the international ellipsoid of reference. [14] |
| 2455 | Infrared Radiation | Electromagnetic radiation with wavelengths between about 0.7 and 1000 mm. This radiation is longer than visible radiation but shorter than microwave radiation. [1] |
| 2456 | Luminous Intensity | See intensity. [14] |
| 2457 | Photochemical Smog | Originally smog meant a mixture of smoke and fog. Today, smog means air that has restricted visibility due to pollution, or pollution formed in the presence of sunlight, photochemical smog. Also see smog. [1] |
| 2458 | Thermometric Depth | See depth. [14] |
| 2459 | Topographic Survey | See survey. [14] |
| 2460 | Angle Of Refraction | The angle between a refracted ray and the perpendicular to the refraction surface. [14] |
| 2461 | Figure Of The Earth | The defining elements of the mathematical surface which approximates the surface of the geoid. The figure of the earth has been proved to be approximately an oblate spheroid. See also geoid and spheroid. [14] |
| 2462 | Geocentric Parallax | See parallax: diurnal. [14] |
| 2463 | Horizontal Parallax | See parallax. [14] |
| 2464 | Line Of Collimation | See collimation. [14] |
| 2465 | Mercator Projection | See projection. [14] |
| 2466 | Micrometer: Transit | A form of registering micrometer with its movable wire placed in the focal plane of an astronomic transit and at right angles to the direction of motion of the image of a star which is observed at or near culmination. The transit micrometer is also termed an impersonal micrometer, because it almost completely eliminates the effect of the personal equation on time observations made with it. [14] |
| 2467 | Reference Direction | A direction used as a basis for comparison of other directions. [14] |
| 2468 | Topographic Feature | A single feature of the surface of the earth such as a mountain or valley. [14] |
| 2469 | Coastwise Navigation | See navigation. [14] |
| 2470 | Course: Great Circle | The direction of the great circle through the point of departure and the destination, expressed as the angular distance from a reference direction, usually north, to the direction of the great circle. The angle varies from point to point along the great circle. At the point of departure it is called initial great-circle course; at the destination it is called final great-circle course. [14] |
| 2471 | Density Of Soundings | Intervals between lines of sounding and soundings in the same line. Density of soundings mostly depends on the scale and nature of the survey. Also called frequency of soundings. [14] |
| 2472 | Hydrostatic Pressure | See pressure. [14] |
| 2473 | Interior Orientation | See orientation. [14] |
| 2474 | Levelling Instrument | An instrument designed for the accurate measurement of height differences by the process of levelling. Its essential parts are a telescope and a spirit level. Also called a level. [14] |
| 2475 | Magnetism: Permanent | Magnetism which is retained for long periods without appreciable reduction, unless the magnet is subjected to a demagnetizing force. Because of the slow dissipation of such magnetism, it is sometimes called subpermanent magnetism. [14] |
| 2476 | Moist Adiabatic Rate | The rate of change of temperature in a rising or descending saturated air parcel. The rate of cooling or warming varies but a common value of 6°c per 1000 m (3.3°f per 1000 ft) is used. [1] |
| 2477 | Multiple Lens Camera | See camera. [14] |
| 2478 | Nature Of The Bottom | See bottom: nature of. [14] |
| 2479 | Navigational Warning | A message containing urgent information relevant to safe navigation broadcast to ships in accordance with the provisions of the international convention for the safety of life at sea, 1974, as amended. See coastal warning, local warning, navarea warning. [14] |
| 2480 | Oceanographic Survey | See survey. [14] |
| 2481 | Micrometer Microscope | A filar micrometer so placed that its wire moves in the focal plane of a microscope. [14] |
| 2482 | Projection: Conformal | A projection in which all angles around any point are correctly represented. In such a projection the scale is the same in all directions about any point. Very small shapes are correctly represented, resulting in an orthomorphic projection. Hence, the terms of 'conformal' and 'orthomorphic' are used synonymously since neither characteristic can exist independently of the other. [14] |
| 2483 | Reversing Thermometer | See thermometer. [14] |
| 2484 | Triangulation Station | See station. [14] |
| 2485 | Radio Direction Finder | Radio receiving equipment which determines the direction of arrival of a signal by measuring the orientation of the wave front or of the magnetic or electric vector. Radio direction finders may be either manual or automatic. Also called direction finder. Formerly called radio compass. [14] |
| 2486 | Reduction Of Soundings | The correction of the observed depths, for the height of tide above or below the plane of reference at the time of sounding. Usually the term reduction of soundings does not cover corrections other than those due to tide. See correction of soundings, lead line correction and tide reducer. [14] |
| 2487 | Tape: Grade Correction | A correction applied to a distance measured on a slope to reduce it to a horizontal distance between the vertical lines through its end points. Also termed slope correction or correction for inclination of tape. [14] |
| 2488 | Chart (Or Map): Weather | Geographical map on which meteorological conditions or elements are represented by figures, symbols, or isopleths. Also called synoptic chart (or map). [14] |
| 2489 | Orthomorphic Projection | See projection: conformal. [14] |
| 2490 | Mean Zero-Crossing Period | Average period of the (up or down) zero-crossing waves in a sea state. NOTE In practice the mean zero-crossing period is often estimated from the zeroth and second moments of the wave spectrum as T_z= T_2= √(m_0 (f)/m_2 (f) )=2π√(m_0 (ω)/m_2 (ω) ) [15] |
| 2491 | Weather Tide | See tide: windward. [14] |
| 2492 | Abyssal Plain | An extensive, flat, gently sloping or nearly level region at abyssal depths. [14] |
| 2493 | Accommodation | The faculty of the human eye to adjust itself to give sharp images for different object distances. In stereoscopy, the ability of the eyes to bring two images into superimposition for stereoscopic viewing. [14] |
| 2494 | Aperture Stop | The physical element (such as a diaphragm, or lens periphery) of an optical system which limits the size of the pencil of rays traversing the system. Also called thestop. Diameter of that part of the lens actually used. [14] |
| 2495 | Apparent Noon | See noon. [14] |
| 2496 | Apparent Wind | See relative wind. [14] |
| 2497 | Azimuth: Grid | The angle in the plane of projection between a straight line and the y-axis of a plane-rectangular coordinate system. See bearing: grid. [14] |
| 2498 | Blind Rollers | Long, high swells which have increased in height, almost to the breaking point, as they pass over shoals or run in shoaling water. Called blind seas in some localities. [14] |
| 2499 | Boundary Wave | See wave: internal. [14] |
| 2500 | Cadastral Map | See map. [14] |
| 2501 | Closing Error | See error of closure. [14] |
| 2502 | Codeclination | 90° minus the declination. See polar distance. [14] |
| 2503 | Compound Tide | See tide. [14] |
| 2504 | Contact Glass | See focal plane plate. [14] |
| 2505 | Contact Plate | See focal plane plate. [14] |
| 2506 | Contact Print | See print. [14] |
| 2507 | Current Cycle | A complete set of tidal current conditions, as those occurring during a tidal day, lunar month, or metonic cycle. [14] |
| 2508 | Diurnal Range | See range. [14] |
| 2509 | Doppler Radar | A radar that determines the velocity of falling precipitation either toward or away from the radar unit by taking into account the doppler shift. [1] |
| 2510 | Draft Forward | See draft. [14] |
| 2511 | Earth Current | See current(s): telluric. [14] |
| 2512 | Elevated Pole | See pole. [14] |
| 2513 | Exercise Area | An area shown on charts within which naval, military or aerial exercises are carried out. Also called military practice area. [14] |
| 2514 | False Station | See eccentric station. [14] |
| 2515 | Farewell Buoy | The outermost buoy marking the entrance to a channel or harbor. Also called sea buoy. Known as landfall buoy in British terminology. [14] |
| 2516 | Fiducial Axes | In photogrammetry, the lines joining opposite fiducial marks on a photograph. Also called photograph axes. [14] |
| 2517 | First Quarter | See phases of the moon. [14] |
| 2518 | Flood Current | See flood stream. [14] |
| 2519 | Geodetic Line | See geodesic line. [14] |
| 2520 | Grid Meridian | See meridian. [14] |
| 2521 | Gyro Repeater | An electrically operated dial repeating at a distance the indications of the master gyro compass. [14] |
| 2522 | Harbour Works | Permanent man-made structures built along the coast which form an integral part of the harbor system such as jetties, moles, quays or other port facilities, coastal terminals, wharves, breakwaters, sea walls, etc. [14] |
| 2523 | Heeling Error | See error. [14] |
| 2524 | Horizon Trace | In photogrammetry, an imaginary line, in the plane of a photograph, which represents the image of the true horizon; it corresponds to the intersection of the plane of a photograph and the horizontal plane containing the internal perspective center or rear nodal point of the lens. Also called horizon line. [14] |
| 2525 | Hummocked Ice | Sea ice piled haphazardly one piece over another, and which may be weathered. [14] |
| 2526 | Internal Wave | See wave. [14] |
| 2527 | Interpolation | The process of determining intermediate values between given values in accordance with some known or assumed rate or system of variation. [14] |
| 2528 | Isobathytherm | A line or surface showing the depths in oceans or lakes at which points have the same temperature. Isobathytherms are usually drawn to show cross sections of the water mass. [14] |
| 2529 | Isogonic Line | A line connecting points of equal magnetic variation. Also called isogonal (or isogonic). [14] |
| 2530 | Junction Buoy | A buoy marking the inner end of a middle ground. Usually called a middle ground buoy in British terminology, without regard to direction of travel. [14] |
| 2531 | Latitude Line | A line of position extending in a generally east-west direction. [14] |
| 2532 | Local Warning | a navigational warning which covers inshore waters, often within the limits of jurisdiction of a harbor or port authority. [14] |
| 2533 | Lookout Tower | Any tower surmounted by a small house in which a watch is habitually kept, as distinguished from an observation tower in which no watch is kept. [14] |
| 2534 | Lost' Station | see station: unrecoverable. [14] |
| 2535 | Lower Transit | See meridian transit. [14] |
| 2536 | Lunar Eclipse | See eclipse. [14] |
| 2537 | Magnification | The apparent enlargement of anything. In optics, the term relates to the properties of lenses and lens systems to produce an image which differs in dimension from the related object. [14] |
| 2538 | Marker Beacon | A radio beacon which radiates a signal to define an area, as an aid to navigation. Usually called marker radio beacon or marker. [14] |
| 2539 | Median Valley | The axial depression of the mid-oceanic ridge system. See rift. [14] |
| 2540 | Metonic Cycle | A period of 19 years, after which the various phases of the moon fall on approximately the same days of the year as in the previous cycle. [14] |
| 2541 | Metric System | A system of weights and measures, based upon the metre. [14] |
| 2542 | Minor Control | See control: photogrammetric. [14] |
| 2543 | Mother Vessel | The lead vessel when surveying with several vessels. [14] |
| 2544 | Nocturnal Arc | See arc: astronomical. [14] |
| 2545 | Observed Tide | Those data from tide observing equipment such as tide gauges, staffs, etc. "actual tides" is an expression often used in referring to "observed tides". [14] |
| 2546 | Ocean Station | As defined by the international civil aviation organization, a specifically located area of ocean surface, roughly square and 200 nautical miles on a side. An ocean station vessel on patrol is said to be 'on station' when it is within the perimeter of the area. [14] |
| 2547 | Offshore Wind | Wind blowing from the land toward the sea. See land breeze. [14] |
| 2548 | Outer Harbour | See harbor. [14] |
| 2549 | Picture Plane | A plane upon which a system of lines or rays from an object to form an image or picture can be projected. In perspective drawing, the system of rays is understood to converge to a single point. In photogrammetry, the photograph is the picture plane. [14] |
| 2550 | Pointing Line | See collimation: line of. [14] |
| 2551 | Pressure Wave | A short-period oscillation of pressure such as that associated with the propagation of sound through the atmosphere; a type of longitudinal wave. [14] |
| 2552 | Radio Bearing | See bearing. [14] |
| 2553 | Radio Compass | See radio direction finder. [14] |
| 2554 | Relative Tilt | See tilt. [14] |
| 2555 | Return Period | (Also called recurrence interval.) The average time until the next occurrence of a defined event. When the time to the next occurrence has a geometric distribution, the return period is equal to the inverse of probability of the event occurring in the next time period, that is, T = 1/P, where T is the return period, in number of time intervals, and P is the probability of the next event's occurrence in a given time interval. [4] |
| 2556 | Reverberation | Continuation of radiant energy, particularly sound by multiple reflection. Sound scattered towards the source, principally from the ocean surface (surface reverberation) or bottom (bottom reverberation), and from small scattering sources in the medium such as bubbles of air and sus-pended solid matter (volume reverberation). [14] |
| 2557 | Rotary Stream | See current: rotary. [14] |
| 2558 | Shaded Relief | See illuminated relief. [14] |
| 2559 | Shore Station | See fixed station. [14] |
| 2560 | Shoreline Map | Shoreline maps are the graphic representation of plane table and photogrammetric surveys. The maps contain graphic data relating to the shoreline, alongshore natural and manmade features, and a narrow zone of natural and manmade features inland from the shoreline. The original sources of a shoreline map are ground survey data and photographs. Utilizing these sources, photogrammetric map compilation techniques, and instruments, cartographers generate shoreline maps, overlays, and associated data. The data are primarily generated to support nautical chart maintenance, new nautical chart construction, and hydrographic survey operations. [14] |
| 2561 | Side Echo(Es) | See echo(es): false. [14] |
| 2562 | Sidereal Year | See year. [14] |
| 2563 | Slave Station | In a radio navigation system, the transmitting station controlled or triggered by the signal received from the master station. Often shortened to slave. [14] |
| 2564 | Solar Eclipse | See eclipse. [14] |
| 2565 | Sound Channel | The region in the water column where sound velocity first decreases to a minimum value with depth and then increases in value as a result of pressure. Above the minimum value sound rays are bent downward, and below the minimum value sound rays are bent upward; the rays are thus trapped in this channel. Sound travelling in a deep channel can be detected thousands of miles from the sound source. [14] |
| 2566 | Sounding Book | See sounding record. [14] |
| 2567 | Sounding Lead | A lead used for determining depth of water. Also referred to as plummet. [14] |
| 2568 | Sounding Mark | (British terminology). A mark erected for control of sounding; its position is determined by plotting using intersections from sextant fixes. [14] |
| 2569 | Sounding Wire | A wire used with a sounding machine in determining depth. [14] |
| 2570 | Speed Of Lens | See aperture: relative. [14] |
| 2571 | Squaring Down | See squares: method of. [14] |
| 2572 | Station Error | See deflection of the vertical. [14] |
| 2573 | Swinging Buoy | See compass adjustment buoy. [14] |
| 2574 | Synoptic Hour | Hour, expressed in terms of ut, at which, by international agreement, meteorological observations are made simultaneously throughout the globe. [14] |
| 2575 | Tracing Cloth | A fine semitransparent linen or cotton cloth sized on one side and dull on the other. [14] |
| 2576 | Tropical Wave | A migratory wavelike disturbance in the tropical easterlies. Tropical waves occasionally intensify into tropical cyclones. They are also called easterly waves. [1] |
| 2577 | Trunnion Axis | See axis: horizontal. [14] |
| 2578 | Two-Way Route | A route within defined limits inside which two-way traffic is established, aimed at providing safe passage of ships through waters where navigation is difficult or dangerous. [14] |
| 2579 | Upper Transit | See meridian transit. [14] |
| 2580 | Vertical Axis | See axis. [14] |
| 2581 | Virtual Image | See image. [14] |
| 2582 | Wind Velocity | See wind vector. [14] |
| 2583 | Wire Sounding | See sounding. [14] |
| 2584 | Air Photograph | See photograph: aerial. [14] |
| 2585 | Air Pollutants | Solid, liquid, or gaseous airborne substances that occur in concentrations high enough to threaten the health of people and animals, to harm vegetation and structures, or to toxify a given environment. [1] |
| 2586 | Arm Of The Sea | A narrow portion of the sea projecting from the main body. The expression is often shortened to 'arm'. [14] |
| 2587 | Audiofrequency | A frequency within the audible range, about 20 to 20.000 cycles per second. Also called sonic frequency. [14] |
| 2588 | Azimuth Circle | See bearing circle. [14] |
| 2589 | Base Apparatus | Any apparatus designed for use in measuring with accuracy and precision the length of a base in triangulation, or the length of a line in traverse. [14] |
| 2590 | Bearing: Rhumb | The direction of a rhumb line through two terrestrial points expressed as angular distance from a reference direction. Also called Mercatorial (or Mercator) bearing. [14] |
| 2591 | Brackish Water | Water in which salinity values range from approximately 0.50 to 17.00 parts per thousand. [14] |
| 2592 | Camera Station | See air station. [14] |
| 2593 | Change Of Tide | A reversal of the direction of motion (rising or falling) of a tide. The expression is also sometimes applied to a reversal in the set of a tidal current. Also called turn of the tide. See also stand of tide. [14] |
| 2594 | Coplane: Basal | In photogrammetry, the condition of exposure of a pair of photographs in which the two photographs lie in a common plane parallel to the air base. If the air base is horizontal, the photographs are said to be exposed in horizontal coplane. [14] |
| 2595 | Dip Correction | That correction to sextant altitude due to the dip of the horizon. Also called height of eye correction. [14] |
| 2596 | Drying Heights | Heights above sounding datum, of any areas (banks, foreshores, rocks, etc.) Which dry at low water. [14] |
| 2597 | Eddy Viscosity | The turbulent transfer of momentum by eddies giving rise to an internal fluid friction, in a manner analogous to the action of molecular viscosity in laminar flow, but taking place on a much larger scale. The value of the coefficient of eddy viscosity is of the order 104 square centimeters per second. [14] |
| 2598 | Entrance Pupil | The image of the aperture stop formed by all the lens elements on the object side of the aperture stop. [14] |
| 2599 | Error Equation | See equation. [14] |
| 2600 | External Error | See error: theoretical. [14] |
| 2601 | Fiducial Marks | In photogrammetry, index marks, usually four, which are rigidly connected with the camera lens through the camera body and which form images on the negative and usually define the principal point of the photograph. Also marks, usually four in number, in any instrument, which define the axes whose intersection fixes the principal point of a photograph and fulfills the requirements of interior orientation. In surveying, an index line or point. A line or point used as a basis of reference. [14] |
| 2602 | Fishing Ground | A water area in which fishing is frequently carried on. Also called fishing area or fishing zone. [14] |
| 2603 | Fixed Platform | See fixed station. [14] |
| 2604 | Floating Point | In computer systems the type of numeric data approximately representing real numbers. A floating point number is composed of an exponent and a mantissa specifying the numerical value relative to the exponent. Owing to the limited length of a computer word, the floating point representation may cause a loss of precision. [14] |
| 2605 | Freezing Point | Temperature of solidification of a liquid in given conditions. [14] |
| 2606 | Friction Layer | Atmospheric layer extending from the earth's surface and of depth about 600 to 800 m, within which air motion is affected significantly by surface friction. Above this layer lies the 'free atmosphere'. [14] |
| 2607 | Global Warming | Increasing global surface air temperatures that show up in the climate record. The term global warming is usually attributed to human activities, such as increasing concentrations of greenhouse gases from automobiles and industrial processes, for example. [1] |
| 2608 | Greenwich Time | See time. [14] |
| 2609 | Heeling Magnet | A permanent magnet placed vertically in a tube under the center of a marine magnetic compass, to correct for heeling error. [14] |
| 2610 | Hertzian Waves | See wave(s): radio. [14] |
| 2611 | Holding Ground | An expression usually used with a modifying adjective to indicate the quality of the holding power of the material constituting the bottom of an anchorage; e.g., of good (or poor) holding ground. [14] |
| 2612 | Index Contours | Certain contour lines (usually every fifth) accentuated by use of a line heavier than the intervening ones. [14] |
| 2613 | List Of Lights | A publication tabulating navigational lights, with their locations, candle powers, characteristics, etc. To assist in their identification, and details of any accompanying fog signal. A list of lights may contain other information useful to a navigator. Also called light list. [14] |
| 2614 | Local Meridian | See meridian. [14] |
| 2615 | Longitude Line | A line of position extending in a generally north-south direction. [14] |
| 2616 | Luminous Range | See range. [14] |
| 2617 | Marine Sextant | See sextant. [14] |
| 2618 | Mass Transport | In oceanography, the voluminous transfer of water from one region to another. [14] |
| 2619 | Master Compass | See compass. [14] |
| 2620 | Masthead Angle | The vertical angle subtended by a ship's mast. [14] |
| 2621 | Modulated Wave | See wave. [14] |
| 2622 | Month: Nodical | The interval of time between two successive passages of the moon through the same node of its orbit. The length of the nodical month averages 27.21222 mean solar days. Also called draconic month. [14] |
| 2623 | Mountain Range | A line of mountains. Also referred to as range of mountains. [14] |
| 2624 | Neap Low Water | See mean low water neaps. [14] |
| 2625 | Photosynthesis | The formation of carbohydrates in living plants from water and carbon dioxide, by the action of sunlight on the chlorophyll. [14] |
| 2626 | Polar Distance | Angular distance from a celestial pole; the arc of an hour circle between a celestial pole, usually the elevated pole, and a point on the celestial sphere, measured from the celestial pole through 180°. When the declination and latitude are of the same name, codeclination is the same as polar distance measured from the elevated pole. [14] |
| 2627 | Position Angle | See parallactic angle. [14] |
| 2628 | Prime Meridian | See meridian. [14] |
| 2629 | Probable Error | See error. [14] |
| 2630 | Range: Diurnal | The difference in height between mean higher high water and mean lower low water. Also called great diurnal range. [14] |
| 2631 | Reference Mark | In surveying, a supplementary mark of permanent character close to a station or to a base terminal, to which it is related by an accurately measured distance and direction, and/or a difference in elevation. [14] |
| 2632 | Reference Tape | A base tape employed solely for use as a standard of comparison. Also called standard tape. [14] |
| 2633 | Relative Speed | See relative movement. [14] |
| 2634 | Remote Sensing | The measurement or acquisition of information of some property of an object or phenomenon by a recording device that is not in physical or infinite contact with the object or phenomenon under study. Sometimes restricted to the practice of data collection in the wavelengths from ultraviolet to radio regions. [14] |
| 2635 | Residual Error | See error. [14] |
| 2636 | Safety Fairway | An area within which permits are not granted for the erection of oil or gas related structures. The use of a safety fairway is not usually mandatory, but is recommended. [14] |
| 2637 | Satellite Boat | A subsidiary boat used in parallel sounding. [14] |
| 2638 | Scale Parallel | Used in Mercator projection charts to indicate the parallel at which the noted scale of the chart is exact. The scale parallel itself need not necessarily be depicted within the chart. [14] |
| 2639 | Secondary Port | See station: subordinate. [14] |
| 2640 | Semimajor Axis | One-half of the longest diameter of an ellipse. [14] |
| 2641 | Semiminor Axis | One-half of the shortest diameter of an ellipse. [14] |
| 2642 | Sidereal Month | See month. [14] |
| 2643 | Slant Distance | The straight-line distance from one point to another, as contrasted with ground distance. This expression is customarily used only when the straight line connecting the two points lies above the surface of the earth. Also called slant range. [14] |
| 2644 | Solar Constant | The rate at which solar energy is received on a surface at the outer edge of the atmosphere perpendicular to the sun's rays when the earth is at a mean distance from the sun. The value of the solar constant is about two calories per square centimeter per minute or about 1376 w/m2 in the si system of measurement. [1] |
| 2645 | Sounding Board | See field board. [14] |
| 2646 | Source Diagram | A small scale map or index placed on a chart to indicate the coverage area, and textual description, of the source data, used in construction of the chart. Also called compilation diagram. [14] |
| 2647 | Speed: Angular | Change of direction per unit time. Also called angular rate or angular velocity. [14] |
| 2648 | Spirit Compass | See compass: liquid. [14] |
| 2649 | Spot Elevation | A point on a map or chart whose elevation is noted. It is usually indicated by a dot accompanied by a number indicating the vertical distance of the point from the reference datum. Spot elevations are used principally to indicate points higher than their surroundings. Also called spot height. [14] |
| 2650 | Transformation | In photogrammetry, the process of projecting a photograph (mathematically, graphically, or photographically) from its plane onto another plane by translation, rotation, and/or scale change. The projection is made onto a plane determined by the angular relations of the camera axes and not necessarily onto a horizontal plane. See also rectification. [14] |
| 2651 | Tropical Month | See month. [14] |
| 2652 | Vanishing Tide | See tide. [14] |
| 2653 | Wave: Standing | A type of wave in which the surface of the water oscillates vertically between fixed points, called nodes, without progression. The points of maximum vertical rise and fall are called antinodes or loops. At the nodes, the underlying water particles exhibit no vertical motion but maximum horizontal motion. At the antinodes the underlying water particles have no horizontal motion and maximum vertical motion. They may be the result of two equal progressive wave trains travelling through each other in opposite directions. Also called stationary wave. [14] |
| 2654 | Well: Offshore | A borehole that produces or is capable of producing oil or natural gas. [14] |
| 2655 | Acid Deposition | The depositing of acidic particles (usually sulfuric acid and nitric acid) at the earth's surface. Acid deposition occurs in dry form (dry deposition) or wet form (wet deposition). Acid rain and acid precipitation often denote wet deposition. (see acid rain.) [1] |
| 2656 | Age Of The Moon | The elapsed time since the last new moon; usually expressed in days and fractions of a day. See phases of the moon. [14] |
| 2657 | Aneroid Capsule | Metallic capsule, of thin sides, partially evacuated by a fixed amount, carrying an arrangement to prevent its collapsing under atmospheric pressure, and whose shape changes in accordance with changes of this pressure. [14] |
| 2658 | Apparent Motion | See relative motion. [14] |
| 2659 | Bathymetric Map | A topographic map of the ocean floor, or the bed of a lake. A topographic chart of the bed of a body of water, or a part of it. Generally, bathymetric maps show depths by contour lines and gradient tints. [14] |
| 2660 | Coastal Warning | A navigational warning, or in-force bulletin, promulgated as part of a numbered series by a national coordinator. [14] |
| 2661 | Compass Bearing | See bearing. [14] |
| 2662 | Contiguous Zone | A zone contiguous to a coastal state's territorial sea, which may not extend beyond 24 nautical miles from the baselines from which the breadth of the territorial sea is measured. The coastal state may exercise certain control in this zone subject to the provisions of international law. [14] |
| 2663 | Course Recorder | A device which makes an automatic record of the headings of a vessel. See dead reckoning tracer. [14] |
| 2664 | Cust Protractor | See protractor. [14] |
| 2665 | Datum: Geodetic | A set of parameters specifying the reference surface or the reference coordinate system used for geodetic control in the calculation of coordinates of points on the earth. Commonly datums are defined as horizontal and vertical datums separately. For a local geodetic datum the reference surface is defined by five parameters: the latitude and longitude of an initial point, the azimuth of a line from this point, and the parameters of the reference spheroid. Absolute datums specify the initial point of the reference ellipsoid to be (ideally) located at the earth's center of mass. For modern reference systems using datum information given by satellites additional parameters are defined, e.g. Gravity models. See also horizontal control datum. [14] |
| 2666 | Datum: Sounding | The horizontal plane or tidal datum to which the soundings on a hydrographic survey are reduced. Also called datum for sounding reduction. [14] |
| 2667 | Diurnal Current | See current. [14] |
| 2668 | Eccentric Angle | See latitude: parametric. [14] |
| 2669 | Elevation Tints | See hypsometric tints. [14] |
| 2670 | Equal Altitudes | Two altitudes of the same celestial body observed east and then west of the meridian, when it has reached the same value. The expression also applies to the practice, essentially obsolete, of determining the instant of local apparent noon by observing equal altitudes of the sun. [14] |
| 2671 | Equisignal Zone | See zone. [14] |
| 2672 | Forward Azimuth | See azimuth: geodetic. [14] |
| 2673 | Geodetic Survey | See survey. [14] |
| 2674 | Gravity Anomaly | The difference between the observed gravity value properly reduced to sea level and the theoretical gravity obtained from gravity formula. See bouguer anomaly, free-air anomaly, isostatic anomaly. [14] |
| 2675 | Half Tide Level | The level midway between mean high water and mean low water. It may differ slightly from mean sea level. Also called mean tide level. [14] |
| 2676 | Hurricane Watch | A hurricane watch indicates that a hurricane poses a threat to an area (often within several days) and residents of the watch area should be prepared. [1] |
| 2677 | Inferior Mirage | See mirage. [14] |
| 2678 | Internal Waters | Waters on the landward side of the baseline of the territorial sea and landlocked waters within the state. [14] |
| 2679 | Inversion Layer | Atmospheric layer, horizontal or approximately so, in which the temperature increases with increasing height. See temperature inversion. [14] |
| 2680 | Irregular Error | See error: accidental. [14] |
| 2681 | Laplace Azimuth | See azimuth. [14] |
| 2682 | Laplace Station | See station. [14] |
| 2683 | Light: Rhythmic | A signal light that shows intermittently, in any given direction, with a regular periodicity. Also referred to as intermittent light. [14] |
| 2684 | Linear Parallax | See parallax: absolute stereoscopic. [14] |
| 2685 | Local Mean Time | See time. [14] |
| 2686 | Luminous Signal | See signal. [14] |
| 2687 | Mean Wind Speed | Time-averaged wind speed, averaged over a specified time interval. NOTE The mean wind speed varies with elevation above mean sea level and the averaging time interval; a standard reference elevation is 10 m and a standard time interval is 1 h. See also Sustained Wind Speed and Gust Wind Speed. [15] |
| 2688 | Micrometer Comb | A notched scale placed at right angles to the movable wire of a micrometer and so designed that one turn of the micrometer screw will move the micrometer wire across one notch of the comb; the central notch of the comb in conjunction with the zero of the micrometer head furnishes a fiducial point from which all micrometer readings are reckoned. The comb is used for keeping count of whole turns of the micrometer screw, parts of turns being read on the graduated micrometer head. [14] |
| 2689 | Minus Soundings | See sounding. [14] |
| 2690 | Navarea Warning | A navigational warning or in-force bulletin promulgated as part of a numbered series by a navarea co-ordinator. [14] |
| 2691 | Neap High Water | See mean high water neaps. [14] |
| 2692 | Normal Equation | See equation. [14] |
| 2693 | Numerical Scale | See scale: natural. [14] |
| 2694 | Perspective Ray | A line joining a perspective center and a point object. [14] |
| 2695 | Phototheodolite | A ground-survey instrument combining a theodolite and a surveying camera in which the relation-ship between the camera axis and the line of collimation of the theodolite can be measured. [14] |
| 2696 | Polyvinyl Corer | See corer: hydroplastic. [14] |
| 2697 | Position Circle | See circle of position. [14] |
| 2698 | Progress Sketch | A map or sketch showing work accomplished. In triangulation and traverse, each point established is shown on the progress sketch as well as lines observed over and bases measured. In a levelling survey, the progress sketch shows the route followed and the towns passed through, but not necessarily the locations of the bench marks. [14] |
| 2699 | Radar Altimeter | See altimeter: radio. [14] |
| 2700 | Radio Altimeter | See altimeter. [14] |
| 2701 | Rainfall Amount | Thickness of the layer of water which accumulates on a horizontal surface, as the result of one or more falls of precipitation, in the absence of infiltration or evaporation, and if any part of the precipitation falling as snow or ice were melted. Also called amount of precipitation. [14] |
| 2702 | Range: Luminous | The greatest distance at which a light can be seen merely as a function of its luminous intensity, the meteorological visibility, and the sensitivity of the observer's eye. [14] |
| 2703 | Recurrence Rate | See repetition rate. [14] |
| 2704 | Reference Plane | See datum: chart, and datum: vertical control. [14] |
| 2705 | Reference Point | Any point which can serve as a reference or base for the measurement of other quantities. Also called datum point. [14] |
| 2706 | Reflected Light | The process whereby a surface turns back a portion of the radiation that strikes it. When the radiation that is turned back (reflected) from the surface is visible light, the radiation is referred to as reflected light. See reflection. [1] |
| 2707 | Reported Danger | An object dangerous to navigation which is shown on a chart but the existence of which has not been confirmed. Sometimes called vigia. [14] |
| 2708 | Restricted Area | A specified area designated by appropriate authority within which access or navigation is restricted in accordance with certain specified conditions. [14] |
| 2709 | Right Ascension | Angular distance east of the vernal equinox; the arc of the celestial equator, or the angle at the celestial pole, between the hour circle of the vernal equinox and the hour circle of a point on the celestial sphere, measured eastward from the hour circle of the vernal equinox through 24 hours. [14] |
| 2710 | Routeing System | Any system of one or more routes or routing measures aimed at reducing the risk of casualties; it includes traffic separation schemes, two-way routes, recommended tracks, areas to be avoided, inshore traffic zones, roundabouts, precautionary areas and deep-water routes. [14] |
| 2711 | Sea Level Datum | A determination of mean sea level that has been adopted as a standard datum of heights although it may differ from a later determination over a longer period of time. [14] |
| 2712 | Subastral Point | See substellar point. [14] |
| 2713 | Subsurface Mark | See underground mark. [14] |
| 2714 | Supercell Storm | A severe thunderstorm that consists primarily of a single rotating updraft. Its organized internal structure allows the storm to maintain itself for several hours. Supercell storms can produce large hail and dangerous tornadoes. [1] |
| 2715 | Superior Mirage | A refraction phenomenon that makes an object appear to be displaced from its true position. When an object appears higher than it actually is, it is called a superior mirage. When an object appears lower than it actually is, it is an inferior mirage. See mirage. [1] |
| 2716 | Three-Point Fix | See fix. [14] |
| 2717 | Tidal Constants | Tidal relations that remain essentially constant for any particular locality. Tidal constants are classed as harmonic and non-harmonic, the harmonic constants consisting of the amplitudes and epochs, and the non-harmonic constants including those values determined directly from observations, such as tidal ranges and intervals. [14] |
| 2718 | Track Made Good | See track. [14] |
| 2719 | Tracking Camera | See camera: ballistic. [14] |
| 2720 | Transition Zone | The water area between two opposing currents manifested by eddies, upwelling, rips, and similar turbulent conditions occurring either vertically or horizontally; or a zone between two water masses of differing physical characteristics such as temperature and/or salinity. [14] |
| 2721 | Transverse Wave | See wave. [14] |
| 2722 | Travelling Wave | See wave: progressive. [14] |
| 2723 | Trochoidal Wave | See wave. [14] |
| 2724 | True Solar Time | See time: apparent solar. [14] |
| 2725 | Variation: Grid | Angular difference in direction between grid north and magnetic north. It is measured east or west from grid north. Also called grivation, or grid magnetic angle. [14] |
| 2726 | Wave Refraction | See refraction of water waves. [14] |
| 2727 | Wave: Modulated | A wave which varies in some characteristic in accordance with the variations of a modulating wave. See wave: continuous. [14] |
| 2728 | Winter Solstice | Approximately December 21 in the northern hemisphere when the sun is lowest in the sky and directly overhead at latitude 231d2°s, the tropic of Capricorn. [1] |
| 2729 | Angular Parallax | See parallactic angle. [14] |
| 2730 | Angular Velocity | See speed: angular. [14] |
| 2731 | Assumed Position | See position. [14] |
| 2732 | Astro-Navigation | See navigation: celestial. [14] |
| 2733 | Benthic Division | In the classification of the marine environment and its inhabitants, a primary division of the sea which includes all of the ocean floor. The other primary division of the sea is the pelagic division. [14] |
| 2734 | Binocular Vision | Simultaneous vision with both eyes. [14] |
| 2735 | Compass Meridian | See meridian. [14] |
| 2736 | Compass Repeater | A device for repeating at a distance the indications of the master compass. [14] |
| 2737 | Continental Rise | a gentle slope rising from the oceanic depths towards the foot of a continental slope. [14] |
| 2738 | Conversion Angle | See arc to chord correction. [14] |
| 2739 | Conversion Scale | A scale for the conversion of units of one measurement to equivalent units of another measurement. See nomogram. [14] |
| 2740 | Conversion Table | A table for the conversion of units of one measurement to equivalent units of another measurement. See nomogram. [14] |
| 2741 | Corrector Magnet | See compensator: magnetic. [14] |
| 2742 | Course Made Good | The actual track made good over the ground (seabed); the direction of the point of arrival from the point of departure. Course made good is the direction component of the resultant ship's velocity and the water current. Course made good should not be confused with heading, or ship's head. [14] |
| 2743 | Deep Ocean Floor | The surface lying at the bottom of the deep ocean. [14] |
| 2744 | Depth Of The Sea | The vertical distance from the water surface to the sea bottom. [14] |
| 2745 | Digital Computer | See computer. [14] |
| 2746 | Diurnal Parallax | See parallax. [14] |
| 2747 | Duration Of Fall | See duration of rise and fall. [14] |
| 2748 | Electronic Chart | A very broad term to describe the data, the software, and sometimes the electronic system, capable of displaying chart information. [14] |
| 2749 | Exposure Station | See air station. [14] |
| 2750 | Fixed Angle Plot | (British terminology). Plot prepared in advance for use in normal sounding in lieu of a station pointer. The arcs of equal angle subtended by selected marks are drawn on the sounding board at convenient intervals depending on the scale. The observed sextant angles can then be plotted in the field by visual inspection. See also circle sheet, and sounding: fixed angle. [14] |
| 2751 | Geodetic Azimuth | See azimuth. [14] |
| 2752 | Geodetic Control | See control. [14] |
| 2753 | Graduation Error | See error of graduation. [14] |
| 2754 | Grid Coordinates | See coordinates. [14] |
| 2755 | Half Convergency | See arc to chord correction. [14] |
| 2756 | Hygrothermograph | Instrument resulting from the combination of a thermograph and a hygrograph and furnishing, on the same diagram, simultaneous time recording of atmospheric temperature and humidity. Also called thermohygrograph. [14] |
| 2757 | Inferior Transit | See meridian transit. [14] |
| 2758 | Initial Meridian | See meridian. [14] |
| 2759 | Inland Ice Sheet | An ice sheet of considerable thickness and more than about 50,000 sq. Km in area, resting on rock. Inland ice sheets near sea level may merge into ice shelves. [14] |
| 2760 | Intercept Method | See marcq st. Hilaire method. [14] |
| 2761 | Local Attraction | Local magnetic disturbance. Also deflection of the plumb line due to a mountain or other irregularity in earth's crust. [14] |
| 2762 | Magnetic Anomaly | See local magnetic disturbance. [14] |
| 2763 | Magnetic Bearing | See bearing. [14] |
| 2764 | Magnetostriction | The phenomenon wherein ferromagnetic material experience an elastic strain when subjected to an external magnetic field. Also, the converse phenomenon in which mechanical stresses cause a change in the magnetic induction of a ferromagnetic material. [14] |
| 2765 | Meridian Passage | See meridian transit. [14] |
| 2766 | Meridional Parts | The length of the arc of a meridian between the equator and a given parallel on a Mercator chart, expressed in units of 1 minute of longitude at the equator. [14] |
| 2767 | Nautical Almanac | See almanac. [14] |
| 2768 | Navigation: Land | Navigation of vehicles across land or ice. The expression is generally used in connection with the crossing of a region devoid of roads or landmarks, so that methods similar to those employed in air or marine navigation must be employed. [14] |
| 2769 | Navigational Aid | (US Terminology). An instrument, device, chart, method, etc., intended to assist in the navigation of a craft. An aid to navigation is a navigational aid but the latter expression should not be confused with the former which refers only to devices external to a craft. [14] |
| 2770 | Neritic Province | See pelagic division. [14] |
| 2771 | Oceanic Province | See pelagic division. [14] |
| 2772 | Optical Parallax | See parallax: instrumental. [14] |
| 2773 | Photograph Nadir | See nadir. [14] |
| 2774 | Rational Horizon | See horizon: celestial. [14] |
| 2775 | Residual Current | Part of the total current that is not constituted from harmonic tidal components (i.e. the tidal stream). NOTE Residual currents are caused by a variety of physical mechanisms and comprise a large range of natural frequencies and magnitudes in different parts of the world. [15] |
| 2776 | Responder Beacon | See transponder beacon. [14] |
| 2777 | Small Correction | (British terminology). Minor corrections made to the chart plates. They have been discontinued since 1954. [14] |
| 2778 | Spherical Excess | The amount by which the sum of the three angles of a spherical triangle exceeds 180°. [14] |
| 2779 | Spheroid: Oblate | An ellipsoid of revolution, the minor axis of which is the axis of revolution. The earth is approximately an oblate spheroid. [14] |
| 2780 | Spirit Levelling | See levelling. [14] |
| 2781 | Static Stability | See stability. [14] |
| 2782 | Subpolar Climate | A climate observed in the northern hemisphere that borders the polar climate. It is characterized by severely cold winters and short, cool summers. Also known as taiga climate and boreal climate. [1] |
| 2783 | Subtropical High | A semipermanent high in the subtropical high-pressure belt centered near 30° latitude. The Bermuda high is located over the Atlantic Ocean off the east coast of north america. The pacific high is located off the west coast of north america. [1] |
| 2784 | Sulfate Aerosols | Tiny suspended solid particles (dust, smoke, etc.) Or liquid droplets that enter the atmosphere from either natural or human (anthropogenic) sources, such as the burning of fossil fuels. Sulfur-containing fossil fuels, such as coal, produce sulfate aerosols. See aerosols. [1] |
| 2785 | Survey: Geodetic | A survey in which the figure and size of the earth is considered. It is applicable for large areas and long lines and is used for the precise location of basic points suitable for controlling other surveys. [14] |
| 2786 | Tidal Difference | Difference in time or height of a high or low water at a subordinate station and at a reference station for which predictions are given in the tide tables. The difference, when applied according to sign to the prediction at the reference station, gives the corresponding time or height for the subordinate station. [14] |
| 2787 | Vibrating Needle | A magnetic needle used in compass adjustment to find the relative intensity of the horizontal components of the earth's magnetic field and the magnetic field at the compass location. Also called horizontal force instrument. See compensation of magnetic compass. [14] |
| 2788 | Water Equivalent | The depth of water that would result from the melting of a snow sample. Typically about 10 inches of snow will melt to 1 inch of water, producing a water equivalent of 10 to 1. [1] |
| 2789 | Wave: Continuous | A series of waves of like amplitude and frequency. See wave: modulated, pulse. [14] |
| 2790 | Weather Elements | The elements of air temperature, air pressure, humidity, clouds, precipitation, visibility, and wind that determine the present state of the atmosphere, the weather. [1] |
| 2791 | Well: Production | A borehole, producing oil or natural gas, which is covered by a seabed installation of valves and pipelines for the controlled removal of the product. See also sub-sea completion. [14] |
| 2792 | Wind Circulation | The flow of air through a given area. [14] |
| 2793 | Adiabatic Process | A thermodynamic change of state of a system in which there is no transfer of heat or mass across the boundaries of the system. In an adiabatic process, compression always results in warming, expansion in cooling. [14] |
| 2794 | Aneroid Barometer | An instrument designed to measure atmospheric pressure. It contains no liquid. [1] |
| 2795 | Annual Aberration | See aberration of light. [14] |
| 2796 | Anomalistic Month | See month. [14] |
| 2797 | Bilby Steel Tower | A demountable and transportable triangulation tower for elevating a theodolite and luminous signals above the ground, designed by j.s. Bilby, usc&gs. [14] |
| 2798 | Centrifugal Force | The force with which a body moving under constraint along a curved path reacts to the constraint. Equal and opposite to the centripetal force. [14] |
| 2799 | Collimation Error | See error of collimation. [14] |
| 2800 | Compass Corrector | See compensator: magnetic. [14] |
| 2801 | Compass: Steering | The compass placed next to the steering wheel, by which the course is steered. See also steering repeater. [14] |
| 2802 | Computer Graphics | All methods and techniques used in computer sciences to represent data in graphical form and to process images. [14] |
| 2803 | Controlled Mosaic | See mosaic. [14] |
| 2804 | Current Direction | See direction of current. [14] |
| 2805 | Daily Retardation | The amount of time by which corresponding tidal phases grow later day by day (averages approximately 50 minutes). [14] |
| 2806 | Datum For Heights | See datum: vertical control. [14] |
| 2807 | Discoloured Water | Unnatural coloured areas in the sea due to the existence of shoals. Sea water having a colour other than the blues and greens normally seen. Variations of the colors red, yellow, green and brown, as well as black and white, have been reported. Discolorations may appear in patches, streaks, or large areas and may be caused by concentrations of inorganic or organic particles or plankton. See red tide. [14] |
| 2808 | False Coordinates | See coordinates. [14] |
| 2809 | Field Examination | A special purpose hydrographic, wire drag, or side scan sonar survey of very limited area; i.e., usually an investigation of one or more individual and scattered items. [14] |
| 2810 | Geodetic Parallel | See parallel. [14] |
| 2811 | Ground Photograph | See photograph: terrestrial. [14] |
| 2812 | Horizon: Apparent | The irregular line along which rays from the point of observation are tangent to the surface of the earth. Also called visible (or local) horizon. [14] |
| 2813 | Hyperbolic System | Radiolocation system supplying hyperbolic lines of position. [14] |
| 2814 | Indian Tide Plane | See indian spring low water. [14] |
| 2815 | Induced Magnetism | See magnetism. [14] |
| 2816 | Intersected Point | See station: intersection. [14] |
| 2817 | Logarithmic Scale | See scale. [14] |
| 2818 | Longshore Current | A current paralleling the shore largely within the surf zone. It is caused by the excess water brought to the zone by the small net mass transport of wind waves. Longshore currents feed into rip currents. [14] |
| 2819 | Magnetic Meridian | See meridian. [14] |
| 2820 | Meridian Altitude | See altitude. [14] |
| 2821 | Meridian Distance | In astronomy, the hour angle of a celestial body when close to but not exactly on the astronomical meridian. In plane surveying, the perpendicular distance in a horizontal plane of a point from a meridian of reference. [14] |
| 2822 | Negative Altitude | See angle of depression. [14] |
| 2823 | No Anchoring Area | A routing measure comprising an area within defined limits where anchoring is hazardous or could result in unacceptable damage to the marine environment. Anchoring in a no anchoring area should be avoided by all ships or certain classes of ships, except in case of immediate danger to the ship or the persons on board. [14] |
| 2824 | Nyquist Frequency | The highest frequency that may be uniquely resolved in a time series from a given sampling interval. The nyquist frequency is equal to twice the sampling interval. Analyzing frequencies for which the nyquist criterion is not met leads to aliasing. [14] |
| 2825 | Observed Altitude | See altitude. [14] |
| 2826 | Personal Parallax | See parallax: instrumental. [14] |
| 2827 | Perspective Plane | Any plane containing the perspective center. The intersection of a perspective plane and the ground will always appear as a straight line on an aerial photograph. [14] |
| 2828 | Plane Coordinates | See coordinates: plane rectangular. [14] |
| 2829 | Point Of Symmetry | The point in the focal plane of a camera about which all lens distortions are symmetrical. If the lens were perfectly mounted, the point of symmetry would coincide with the principal point. [14] |
| 2830 | Polar Coordinates | See coordinates. [14] |
| 2831 | Positive Altitude | See angle of elevation. [14] |
| 2832 | Radiative Forcing | An increase (positive) or a decrease (negative) in net radiant energy observed over an area at the tropopause. An increase in radiative forcing may induce surface warming, whereas a decrease may induce surface cooling. [1] |
| 2833 | Recommended Track | A route which has been specially examined to ensure so far as possible that it is free of dangers and along which, ships are advised to navigate. [14] |
| 2834 | Relative Humidity | The ratio of the actual vapor pressure to the vapor pressure corresponding to saturation at the prevailing temperature. [14] |
| 2835 | Run Of Micrometer | See error of run. [14] |
| 2836 | Spheroid: Prolate | An ellipsoid of revolution, the major axis of which is the axis of revolution. [14] |
| 2837 | Spirit Level Axis | See axis of spirit level. [14] |
| 2838 | Spring High Water | See mean high water springs. [14] |
| 2839 | Tidal Constituent | also known as a Constituent Tide; One of the harmonic elements in a mathematical expression for the tide-producing force and in corresponding formulas for the tide or tidal current. Each constituent represents a periodic change or variation in the relative positions of the Earth, Moon and Sun. [21] |
| 2840 | Tidal Constituent | See harmonic constituent. [14] |
| 2841 | Velocity Of Sound | See sound velocity. [14] |
| 2842 | Angle Of Elevation | The angle in the vertical plane between the horizontal and the line to an object above the horizon. Also called positive altitude. [14] |
| 2843 | Apparent Shoreline | The seaward limit of marine vegetation, such as mangrove, marsh grass, or trees in water that would reasonably appear to the mariner from a distance to be the fast shoreline. The seaward limit of kelp, low grass in water, and other low ‘lying vegetation normally does not constitute an apparent shoreline. A line drawn on the chart in lieu of the mean high-water line or the mean water level line in areas where either may be obscured by marsh, mangrove, cypress, or other type of marine vegetation. This line represents the intersection of the appropriate datum with the outer limits of vegetation and appears to the navigator as shoreline. [14] |
| 2844 | Archipelagic State | A state constituted wholly by one or more archipelagos, eventually including other islands. [14] |
| 2845 | Artificial Horizon | See horizon. [14] |
| 2846 | Celestial Latitude | See latitude. [14] |
| 2847 | Centre Of Buoyancy | See buoyancy. [14] |
| 2848 | Compass Adjustment | See compensation of magnetic compass. [14] |
| 2849 | Compressional Wave | See wave. [14] |
| 2850 | Cooling Degree-Day | A form of degree-day used in estimating the amount of energy necessary to reduce the effective temperature of warm air. A cooling degree-day is a day on which the average temperature is one degree above a desired base temperature. [1] |
| 2851 | Coordinates: False | Grid coordinates obtained by adding fixed numerical quantities to all grid values. These quantities are so large that none of the resultant false coordinates are negative. Such a procedure introduces a false origin to the south and west of the true origin. See coordinates: origin of. [14] |
| 2852 | Coordinates: Plane | See coordinates: plane rectangular. [14] |
| 2853 | Diurnal Aberration | See aberration of light. [14] |
| 2854 | Eyepiece: Erecting | An eyepiece containing an auxiliary re-imagining system of one or two lenses which inverts the primary image before it reaches the eyepiece proper. The device is now obsolescent, the inversion being performed by prism systems. Also called inverting eyepiece. [14] |
| 2855 | Fundamental Circle | See primary great circle. [14] |
| 2856 | Geometric Latitude | See latitude: parametric. [14] |
| 2857 | Great Circle Track | See track. [14] |
| 2858 | Gyroscopic Compass | See compass. [14] |
| 2859 | Gyroscopic Inertia | The property of a gyroscope of resisting any force which tends to change its axis of rotation. A gyroscope tends to maintain the direction of its axis of rotation in space. [14] |
| 2860 | Hand Lead Sounding | See sounding. [14] |
| 2861 | Harmonic Constants | The amplitude and epochs of the harmonic constituent of the tide, or tidal current at any place. [14] |
| 2862 | Horizontal Control | See control. [14] |
| 2863 | Illuminated Relief | The representation of relief with the appearance of lighting from one or more directions, giving a three-dimensional impression. Also called shaded relief. [14] |
| 2864 | Isometric Parallel | See parallel. [14] |
| 2865 | Large Scale Survey | See survey. [14] |
| 2866 | Latitude: Geodetic | The angle which the normal at a point on the spheroid makes with the plane of the geodetic equator. [14] |
| 2867 | Lithographic Image | An ink-receptive image on the lithographic press plate, either photographic or direct hand or transfer image. The design or drawing on stone or metal plate. [14] |
| 2868 | Magnetic Deviation | See deviation. [14] |
| 2869 | Magnetic Intensity | See magnetic field intensity. [14] |
| 2870 | Micrometer: Ocular | A filar micrometer so placed that its wire moves in the principal focal plane of a telescope. Also called an eyepiece micrometer. [14] |
| 2871 | Nautical Astronomy | See astronomy. [14] |
| 2872 | Orientation: Basal | In photogrammetry, the establishment of the position of both ends of an air base with respect to a ground system of coordinates. In all, six elements are required. These are essentially the three-dimensional coordinates of each end of the base. [14] |
| 2873 | Position: Detached | In hydrographic survey, an expression indicating a position taken, to locate rocks, floating aids to navigation, least depths on shoals or other dangers or features of importance. [14] |
| 2874 | Preliminary Survey | See survey: reconnaissance. [14] |
| 2875 | Principal Parallel | See parallel: photograph. [14] |
| 2876 | Reciprocal Bearing | See bearing. [14] |
| 2877 | Resonant Frequency | See frequency. [14] |
| 2878 | Shallow Water Wave | See wave: transitional water. [14] |
| 2879 | Sonic Depth Finder | See echo sounder. [14] |
| 2880 | Static Instability | See instability. [14] |
| 2881 | Stereoscopic Image | The mental impression of a three-dimensional model which results from viewing two overlapping perspective views. Also called stereoscopic model or stereo model. [14] |
| 2882 | Tape Correction(S) | Corrections applied to a distance measured with a tape to eliminate errors caused by the physical condition of the tape, and to the manner in which it is used. [14] |
| 2883 | Tidal Observations | See observation. [14] |
| 2884 | Topographic Signal | See signal. [14] |
| 2885 | Track: Recommended | A track, shown on a chart by either a dashed or a continuous line, recommended to all or only certain vessels. [14] |
| 2886 | Transit Instrument | See transit. [14] |
| 2887 | Transit Micrometer | See micrometer. [14] |
| 2888 | Transponder Beacon | A beacon having a transponder. Also called responder beacon. [14] |
| 2889 | Unit Magnetic Pole | In magnetic theory, a fictitious entity analogous to a unit electric charge in electrostatic theory. [14] |
| 2890 | Aeronautical Beacon | See beacon. [14] |
| 2891 | Angle Of Depression | The angle in the vertical plane between the horizontal and the line to an object below the horizon. Also called negative altitude. [14] |
| 2892 | Angle Of Reflection | The angle between the line of motion of a reflected ray and the perpendicular to a surface at the point of reflection. [14] |
| 2893 | Apparent Solar Time | See time. [14] |
| 2894 | Broadcast Ephemeris | Ephemeris transmitted by a satellite which describes its position and orbital parameters. [14] |
| 2895 | Celestial Longitude | See longitude. [14] |
| 2896 | Condensation Nuclei | Also called cloud condensation nuclei. Tiny particles upon whose surfaces condensation of water vapor begins in the atmosphere. [1] |
| 2897 | Depth Anomaly Graph | A graph constructed to determine the difference between the computed or thermometric depth and the ideal or assumed depth of reversal of thermometers attached to a nansen bottle. [14] |
| 2898 | Ekman Current Meter | A widely used instrument for measuring the speed and direction of the current at any depth. It is designed for use from a ship or boat at anchor when the stream does not attain a rate of more than 3 to 3 1/2 knots. [14] |
| 2899 | Error: Polarization | Error in a radio bearing or the course indicated by a radio beacon, due to horizontally-polarized components of the electric field under certain transmission conditions. The terms night error or night effect have become obsolete. [14] |
| 2900 | Great Circle Course | See course. [14] |
| 2901 | High Water Interval | See lunitidal interval. [14] |
| 2902 | Hydrographic Signal | See signal. [14] |
| 2903 | Instability: Static | State of hydrostatic equilibrium of the atmosphere in which a particle of air moved from its initial level undergoes a hydrostatic force which tends to remove it further from this level. Also called hydrostatic instability. [14] |
| 2904 | Local Apparent Time | See time. [14] |
| 2905 | Longitude: Geodetic | The angle between the plane of the geodetic meridian and the plane of an initial meridian, arbitrarily chosen. [14] |
| 2906 | North Magnetic Pole | See magnetic pole. [14] |
| 2907 | Offshore Navigation | See navigation. [14] |
| 2908 | Parametric Latitude | See latitude. [14] |
| 2909 | Permanent Magnetism | See magnetism. [14] |
| 2910 | Photograph Meridian | See meridian. [14] |
| 2911 | Photograph Parallel | See parallel. [14] |
| 2912 | Radio Range Station | A radio navigation land station in the aeronautical radio navigation service providing radio equisignal zones. In certain instances a radio range station may be placed aboard a ship. [14] |
| 2913 | Range Of Visibility | The extreme distance at which an object or light can be seen. See range: geographical, and range: luminous. [14] |
| 2914 | Reference Ellipsoid | See reference spheroid. [14] |
| 2915 | Repeatable Accuracy | In a navigation system, the measure of the accuracy with which the system permits the user to return to a position as defined only in terms of the coordinates peculiar to that system. For example, the distance specified for the repeatable accuracy of the system such as loran’s is the distance bet-ween two loran’s positions established using the same stations and time difference readings at different times. The correlation between the geographical coordinates and the system coordinates may or may not be known. [14] |
| 2916 | Self-Aligning Level | See levelling instrument: self-aligning level. [14] |
| 2917 | Sidereal Hour Angle | See hour angle. [14] |
| 2918 | Stereoscopic Fusion | The mental process which combines the two perspective views to give an impression of a three-dimensional model. [14] |
| 2919 | Supercell Tornadoes | Tornadoes that occur within supercell thunderstorms that contain well-developed, mid-level mesocyclones. [1] |
| 2920 | Surface Temperature | Temperature of the water of the surface layer of the sea (or lake, river, etc.). [14] |
| 2921 | Transient Magnetism | See magnetism: temporary. [14] |
| 2922 | Triangulation Point | See station: triangulation. [14] |
| 2923 | Tropical Rainforest | A type of forest consisting mainly of lofty trees and a dense undergrowth near the ground. [1] |
| 2924 | Universal Time (Ut) | Time as defined by the rotational motion of the earth and determined from the apparent diurnal motions which reflect this rotation. Because of variations in the rate of rotation, universal time is not rigorously uniform. Also called Greenwich mean time. [14] |
| 2925 | Vertical Collimator | See collimator. [14] |
| 2926 | Amplitude Modulation | See modulation. [14] |
| 2927 | Azimuthal Projection | See projection. [14] |
| 2928 | Compass Compensation | See compensation of magnetic compass. [14] |
| 2929 | Conformal Projection | See projection. [14] |
| 2930 | Dangerous Semicircle | Region of a tropical cyclone, situated to the right of its path in the northern hemisphere and to the left of its path in the southern hemisphere, in which the seas are higher and the winds more violent and tend also to carry shipping forward on to the cyclone's path. The other half of the cyclone is termed the navigable semicircle. [14] |
| 2931 | Dead Reckoning Track | See track. [14] |
| 2932 | Direction Of Current | The direction toward which a current is flowing, called the set of the current. Also called current direction. [14] |
| 2933 | Direction Of Gravity | See gravity. [14] |
| 2934 | Geometric Projection | See projection: perspective. [14] |
| 2935 | Great Circle Bearing | See bearing. [14] |
| 2936 | Great Circle Sailing | See sailing. [14] |
| 2937 | Illuminated Contours | An application of illuminated relief in which contours appear lighter on illuminated slopes and darker on the shadow slopes. [14] |
| 2938 | Inferior Conjunction | See conjunction. [14] |
| 2939 | International Voyage | A voyage from a country to which the 1974 solas convention applies to a port outside that country or conversely (solas chapter 1, regulation 2d). [14] |
| 2940 | Interocular Distance | See interpupillary distance. [14] |
| 2941 | Intersection Station | See station. [14] |
| 2942 | Latitude: Geocentric | The angle at the center of the earth between the plane of the equator and a line to a point on the surface of the earth. [14] |
| 2943 | Lead Line Correction | A correction to be applied to the depths taken with a rope lead line to take into account the shrinking and stretching. This difficulty has been overcome by inserting a wire heart in the rope. [14] |
| 2944 | Magnetic Observatory | A place where buildings are equipped for observing temporal changes in the earth's magnetic field. [14] |
| 2945 | Magnetic Retentivity | The ability to retain magnetism after removal of the magnetizing force. Also called remanence. [14] |
| 2946 | Magnetism: Temporary | Magnetism of craft which changes in amount with every change of heading. Also called transient magnetism. [14] |
| 2947 | Nonsupercell Tornado | A tornado that occurs with a cloud that is often in its growing stage, and one that does not contain a midlevel mesocyclone, or wall cloud. Landspouts and gustnadoes are examples of nonsupercell tornadoes. [1] |
| 2948 | Operating Conditions | Most severe combination of environmental conditions under which a given operation will be permitted to proceed. NOTE Operating conditions are determined for operations that exert a significant action on the structure. Operating conditions are usually a compromise: they are sufficiently severe that the operation can generally be performed without excessive downtime, but they are not so severe that they have an undue impact on design. [15] |
| 2949 | Parallel Of Latitude | See parallel. [14] |
| 2950 | Plane Table Traverse | See traverse. [14] |
| 2951 | Quadrantal Deviation | See deviation. [14] |
| 2952 | Repeating Instrument | See theodolite: repeating. [14] |
| 2953 | Saint Hilaire Method | See marcq st. Hilaire method. [14] |
| 2954 | Satellite Navigation | A positioning method using satellites. [14] |
| 2955 | Terrestrial Meridian | See meridian: astronomical. [14] |
| 2956 | Three-Arm Protractor | See protractor: three-arm. [14] |
| 2957 | Tropical Wet Climate | A tropical climate with sufficient rainfall to produce a dense tropical rainforest. [1] |
| 2958 | Altitude: Ex-Meridian | An altitude of a celestial body near the celestial meridian of the observer, to which a correction is to be applied to determine the meridian altitude. Also called circummeridian altitude. [14] |
| 2959 | Face(S) Of Theodolite | Either of the two positions, 'face left' (f.l.) And 'face right' (f.r.) Of the theodolite, when observations are made with the vertical circle on the left or on the right of the telescope respectively. [14] |
| 2960 | Hyperbolic Navigation | See navigation. [14] |
| 2961 | Leeward Tidal Current | See tide: leeward. [14] |
| 2962 | Light Characteristics | See characteristics of light. [14] |
| 2963 | List Of Radio Signals | A publication tabulating and combining particulars of: coast radio stations, port radio stations, radio direction finding stations, radio beacons, etc., as well as other information on radio services useful to a navigator. [14] |
| 2964 | Long Range Navigation | See navigation. [14] |
| 2965 | Magnetic Compensation | See compensation of magnetic compass. [14] |
| 2966 | Magnetic Permeability | The property of a magnetizable substance that determines the degree in which it modifies the magnetic flux in the region occupied by it. [14] |
| 2967 | Most Probable Maximum | Value of the maximum of a variable with the highest probability of occurring. NOTE The most probable maximum is the value for which the probability density function of the maxima of the variable has its peak. It is also called the mode or modus of the statistical distribution. [15] |
| 2968 | Navigational Triangle | See astronomical triangle. [14] |
| 2969 | Ocean Weather Station | Station aboard a suitably equipped and staffed ship which tries to maintain a fixed maritime location and which observes and reports for international exchange the observations of specified elements. [14] |
| 2970 | Orientation: Interior | In photogrammetry, the determining (analytically or in a photogrammetric instrument) of the interior perspective of the photograph as it was at the instant of exposure. Elements of interior orientation are the calibrated focal length, location of the calibrated principal point, and the calibrated lens distortion. Also called inner orientation. [14] |
| 2971 | Quadrantal Correctors | Masses of soft iron placed near a magnetic compass to correct for quadrantal deviation. Spherical quadrantal correctors are called quadrantal spheres. [14] |
| 2972 | Spherical Coordinates | See coordinates. [14] |
| 2973 | Theodolite: Repeating | A theodolite so designed that successive measures of an angle may be accumulated on the graduated circle, and a final reading of the circle made which represents the sum of the repetitions. The observed value of the angle is obtained by dividing the total arc passed through in making the series of observations by the number of times the angle has been observed. Also called repeating instrument. See repetition method of observation. [14] |
| 2974 | Tide-Generating Force | See tide-producing force. [14] |
| 2975 | Triangulation: Arc Of | A system of triangulation of limited width designed to progress in a single general direction. Also called chain of triangulation. [14] |
| 2976 | Trigonometric Station | See station: triangulation. [14] |
| 2977 | Wave: Electromagnetic | Wave(s) of associated electric and magnetic fields characterized by variations of the fields. The electric and magnetic fields are at right angles to each other and to the direction of propagation. An electromagnetic wave is coherent if the phase-time relationship is constant throughout the propagation path. [14] |
| 2978 | Automatic Gain Control | A circuit which automatically maintains a constant output volume regardless of input signal strength. Also called automatic volume control. [14] |
| 2979 | Design Crest Elevation | Extreme crest elevation measured relative to still water. [14] |
| 2980 | Eccentricity Of Circle | The distance between the center of figure of a graduated circle of an instrument and its center of rotation. [14] |
| 2981 | Flux-Gate Magnetometer | See magnetometer. [14] |
| 2982 | Long-term Distribution | Probability distribution of a variable over a long time scale. NOTE The time scale exceeds the duration of a sea state, in which the statistics are assumed constant (see shortterm distribution in Short-term Distribution). The time scale is hence comparable to a season or to the design service life of a structure. NOTE The time scale exceeds the duration of a sea state, in which the statistics are assumed constant (see shortterm distribution in Short-term Distribution). The time scale is hence comparable to a season or to the design service life of a structure. [15] |
| 2983 | Meteorological Element | Atmospheric variable or phenomenon which characterize the state of the weather at a specific place at a given time: air temperature, atmospheric pressure, wind, humidity, thunderstorm, fog, precipi-tation, etc. [14] |
| 2984 | Perspective Projection | See projection. [14] |
| 2985 | Projection: Equal Area | A projection having a constant area scale. Such a projection is not conformal and is not used for navigation. Also called equivalent projection. [14] |
| 2986 | Sonic Line Of Position | A line of position determined by means of sound waves. Also called acoustic line of position. [14] |
| 2987 | Station: Triangulation | A recoverable point on the earth, whose geographic position has been determined by angular methods with geodetic instruments. A triangulation station is a selected point, which has been marked with a station mark, or it is a conspicuous natural or artificial object. Also called trigonometric station or triangulation point. [14] |
| 2988 | Terrestrial Photograph | See photograph. [14] |
| 2989 | Tide(S): Shallow Water | A distortional effect upon astronomically generated tide caused by shallow waters. See also tide(s): quarter-diurnal. [14] |
| 2990 | Track Line Of Sounding | A continuous record of soundings obtained by a ship on an extended voyage en route between its home port and the working ground. Also called cruise line of sounding. [14] |
| 2991 | Vertical Control Datum | See datum. [14] |
| 2992 | Artificial Intelligence | 1. The capability of a device to perform functions that are normally associated with human intelligence, such as reasoning, learning, and self ‘improvement. 2. Research and study in methods for the development of a machine that can improve its own operations. The development or capability of a machine that can proceed or perform functions that are normally associated with human intelligence, as learning, adapting, reasoning, self ‘correction, automatic improvement. 3. The study of computer and related techniques to supplement the intellectual capabilities of man. As man has invented and used tools to increase his physical powers, he now is beginning to use artificial intelligence to increase his mental powers. In a more restricted sense, the study of techniques for more effective use of digital computers by improved programming techniques. [14] |
| 2993 | Difference Of Longitude | The angle at the pole or intercepted arc of equator between the meridians of two places. [14] |
| 2994 | Eccentricity Of Alidade | The distance between the center of figure of the index points of an alidade and the center of figure of the graduated circle. [14] |
| 2995 | Electrical Thermometers | Thermometers that use elements that convert energy from one form to another (transducers). Common electrical thermometers include the electrical resistance thermometer, thermocouple, and thermistor. [1] |
| 2996 | Equivalent Focal Length | See focal length. [14] |
| 2997 | Exclusive Economic Zone | The exclusive economic zone is an area, not exceeding 200 nautical miles from the baselines from which the breadth of the territorial sea is measured, subject to a specific legal regime established in the united nations convention on the law of the sea under which the coastal state has certain rights and jurisdiction. [14] |
| 2998 | Geostationary Satellite | A satellite that orbits the earth at the same rate that the earth rotates and thus remains over a fixed place above the equator. [1] |
| 2999 | Geostationary Satellite | An earth satellite moving eastward in an equatorial, circular orbit at an altitude (approximately 35,900 kilometers) such that its period of revolution is exactly equal to (synchronous with) the rotational period of the earth. Such a satellite will remain fixed over a point on the earth's equator. Although geostationary satellites are frequently called geosynchronous or synchronous satellites, the orbit of an eastward moving synchronous satellite must be equatorial if the satellite is to remain fixed over a point on the equator. Otherwise, the satellite moves daily in a figure-eight pattern relative to the earth. Also called fixed satellite. [14] |
| 3000 | Significant Wave Height | The average height of the one-third highest waves of a given wave group or sample. [9] |
| 3001 | Significant Wave Period | Ts ; The significant period is apt to be the average period of all waves whose troughs are below and whose crests are above the mean water level (zero up-crossing method). The significant wave period usually obtained by visual observations of waves is likely to be the average period of 10 to 15 successive prominent waves. [26] |
| 3002 | Submarine Sound Channel | A water layer with minimum sound velocity and high concentration of sound energy in which sound waves are propagated without reflection from sea surface or bottom. [14] |
| 3003 | Tape: Length Correction | The difference between the nominal length of a tape and its effective length under conditions of standardization. [14] |
| 3004 | Kelvin Temperature Scale | Thermodynamic scale of temperature (t°k) defined by assigning to the triple point of pure water, considered as a fundamental fixed point, the temperature of 273.16°k. Also called absolute temperature scale. [14] |
| 3005 | Swath(E) Sounding System | A multi-beam system which is capable of obtaining a lane of soundings from a single ship's track. [14] |
| 3006 | Celsius Temperature Scale | A thermodynamic scale of temperature (t°c) defined as a function of the kelvin temperature scale (t°k) by the relationship t°c = t°k 273.15. Name for anders celsius (1701-44), swedish astronomer who first described, in 1742, the centigrade temperature scale. Note. According to a resolution of the ninth international conference on weights and measures (1948), temperature should be designated 'degrees Celsius' and the designation 'degrees centigrade' should be discontinued. [14] |
| 3007 | Deviation Of The Vertical | See deflection of the vertical. [14] |
| 3008 | Harmonic Analysis Of Tide | The mathematical process by which the observed tide at a place is analyzed by breaking it down into a number of constituent tides of simple periodic forces, each having a fixed period. In this process the sun and moon are replaced by a number of hypothetical tide-producing bodies which move in circular orbits around the earth in the plane of the equator. See harmonic constants, harmonic constituent. [14] |
| 3009 | Hydrographic Survey Sheet | An inclusive term used to designate both boat sheets and smooth sheets. Also called survey sheet. [14] |
| 3010 | International Atomic Time | See atomic time: international. [14] |
| 3011 | Meteorological Visibility | See visibility. [14] |
| 3012 | Rotating Loop Radiobeacon | See rotating radio beacon station. [14] |
| 3013 | Shallow Water Constituent | A short-period harmonic term introduced into the formula of astronomical tide constituents to take account of the change in the form of a tide wave resulting from shallow water conditions. Shallow water constituents include over tides and compound tides. See harmonic constituent. [14] |
| 3014 | Traffic Separation Scheme | A routing measure aimed at the separation of opposing streams of traffic by appropriate means and by the establishment of traffic lanes. [14] |
| 3015 | Deflection Of The Vertical | The angle at a point on the earth (geoid) between the vertical (direction of the plumb line) and the direction of the normal to the spheroid of reference through the point. Also called deflection of the plumb line, deviation of the vertical, or station error. [14] |
| 3016 | Eccentricity Of Instrument | The combination of eccentricity of circle and eccentricity of alidade. The effect of eccentricity of instruments on an observed direction is eliminated by having the verniers or micrometer microscopes, with which the circle is read, spaced at equal distances around the circle. [14] |
| 3017 | Underwater Position Fixing | A method of position fixing for surface vessels, submersibles or towed devices in relation to a network of underwater acoustic beacons on the seabed with known relative positions. [14] |
| 3018 | Hunter Short Base Apparatus | A base apparatus designed for measuring short bases by the subtended method. It consists of a jointed steel tape made up of four sections suspended in catenary between regularly spaced supports. The hunter short base apparatus may be used over rough ground which is unsuitable for ground taping. [14] |
| 3019 | Initial Great Circle Course | See course: great circle. [14] |
| 3020 | Error Of Closure Of Triangle | The amount by which the sum of the three observed angles of a triangle fails to equal exactly 180° plus the spherical excess of the triangle. Also referred to as closure of triangle. [14] |
| 3021 | Continental (Or Island) Shelf | A zone adjacent to a continent (or around an island), extending from the low water line to the depth at which there is usually a marked increase of slope to greater depth. See shelf.- 2- in UNCLOS article 76:- the continental shelf of a coastal state comprises the sea bed and subsoil of the submarine areas that extend beyond its territorial sea throughout the natural prolongation of its land territory to the outer edge of the continental margin, or to a distance of 200 nautical miles from the baselines from which the breadth of the territorial sea is measured where the outer edge of the continental margin does not extend out to that distance. [14] |
| 3022 | Protected Reversing Thermometer | see thermometer. [14] |
| 3023 | Equinoctial System Of Coordinates | See celestial equator system of coordinates. [14] |
| 3024 | Distance Measuring Equipment (Dme) | See electronic distance measuring equipment. [14] |
| 3025 | Duration Of Flood And Duration Of Ebb | Duration of flood is the interval of time in which a tidal current is flooding, and the duration of ebb is the interval in which it is ebbing; these intervals being reckoned from the middle of the intervening slack waters or minimum currents. Together they cover, on an average, a period of 12.42 hours for a semidiurnal tidal current or a period of 24.84 hours for a diurnal current. In a normal semidiurnal tidal current, the duration of flood and duration of ebb will each be approximately equal to 6.21 hours, but the times may be modified greatly by the presence of a non-tidal flow. In a river the duration of ebb is usually longer than the duration of flood because of the fresh water discharge, especially during the spring months when snow and ice melt are the predominant influences. [14] |
| 3026 | Duration Of Rise And Duration Of Fall | Duration of rise is the interval from low water to high water, and duration of fall is the interval from high water to low water. Together they cover, on an average, a period of 12.42 hours for a semidiurnal tide or a period of 24.84 hours for a diurnal tide. In a normal semidiurnal tide, the duration of rise and duration of fall will each be approximately equal to 6.21 hours, but in shallow waters and in rivers there is a tendency for a decrease in the duration of rise and a corresponding increase in the duration of fall. [14] |
| 3027 | Witness Mark | A mark placed at a known distance and direction from a property corner, base terminal, or survey station, to aid in its recovery and identification. [14] |
| 3028 | Absolute Zero | A temperature reading of 2273°c, 2460°f, or 0k. Theoretically, there is no molecular motion at this temperature. [1] |
| 3029 | Abyssal Hills | A tract of small elevations on the deep-sea floor. [14] |
| 3030 | Active System | Any electromagnetic or sonic position fixing system operating with an interrogation-response procedure. See also passive system. [14] |
| 3031 | Advection Fog | Occurs when warm, moist air moves over a cold surface and the air cools to below its dew point. [1] |
| 3032 | Ambient Noise | The erratic electromagnetic or sonic background noise emitted by natural or artificial sources contaminating the proper signal. [14] |
| 3033 | Angle: Danger | See danger angle. [14] |
| 3034 | Angular Speed | See speed. [14] |
| 3035 | Arctic Circle | The geographical parallel having a north latitude equal to the complement of the declination of the summer solstice (latitude = 66 deg 33' n approximately). [14] |
| 3036 | Astro Compass | See under compass. [14] |
| 3037 | Axis: Optical | See axis of lens. [14] |
| 3038 | Azimuth: True | Azimuth relative to true north. [14] |
| 3039 | Basal Coplane | See coplane: basal. [14] |
| 3040 | Basic Control | See control. [14] |
| 3041 | Beacon: Radio | See radio beacon. [14] |
| 3042 | Bearing Plate | See pelorus. [14] |
| 3043 | Bearing: Grid | Bearing relative to grid north. See also azimuth: grid. [14] |
| 3044 | Bearing: True | See bearing. [14] |
| 3045 | Bowditch Rule | A method of adjustment of traverses. [14] |
| 3046 | Bridge: Swing | A movable bridge which rotates in a horizontal plane about a vertical pivot to allow the passage of vessels. [14] |
| 3047 | Buoy: Fairway | A buoy intended to be the first to be seen during an approach from the open sea to a fairway. [14] |
| 3048 | Buoy: Lateral | A buoy used to indicate a lateral limit of navigable water. [14] |
| 3049 | Buoy: Mooring | A buoy secured to the bottom by permanent moorings with means for mooring a vessel by use of its anchor chain or mooring lines. [14] |
| 3050 | Buoy: Special | A buoy primarily used to indicate an area or feature referred to in nautical documents rather than to assist navigation. [14] |
| 3051 | Cable: Leader | Cable lying on the bottom and carrying an electric current by which ships equipped with appropriate instruments, can be guided. [14] |
| 3052 | Calendar Line | See date line. [14] |
| 3053 | Cardinal Buoy | See cardinal mark [14] |
| 3054 | Cardinal Mark | In the iala maritime buoyage system a navigation mark used in conjunction with the compass to indicate where the mariner may find the best navigable water. It is placed in one of the four quadrants (north, east, south and west) bounded by inter-cardinal bearings from the point marked. [14] |
| 3055 | Cellular Wave | See wave. [14] |
| 3056 | Celsius Scale | A temperature scale where zero is assigned to the temperature where water freezes and 100 to the temperature where water boils (at sea level). [1] |
| 3057 | Chart Reading | Interpretation of the symbols, lines, abbreviations, and terms appearing on charts. May be called map reading when applied to maps generally. [14] |
| 3058 | Chart: Marine | See chart: nautical. [14] |
| 3059 | Charted Depth | See depth. [14] |
| 3060 | Circle: Great | The intersection of a sphere and a plane through its center. See also orthodrome. [14] |
| 3061 | Circle: Small | The intersection of a sphere and a plane which does not pass through its center. [14] |
| 3062 | Cleared Depth | The effective depth over a feature, obtained by a wire drag survey. [14] |
| 3063 | Clearing Line | A straight line, on a chart, that marks the boundary between a safe and a dangerous area; or that passes clear of a navigational danger. Sectors of lighthouse lights are usually bounded by them. [14] |
| 3064 | Clock: Atomic | A precision clock that depends for its operation on an electrical oscillator regulated by the natural vibrational frequency of an atomic system (such as a beam). The combination of two (or more) radionuclides whose activities can be utilized to ascertain time intervals. [14] |
| 3065 | Clock: Cesium | An atomic clock using the properties of cesium. [14] |
| 3066 | Clock: Quartz | See clock: crystal. [14] |
| 3067 | Cloud Seeding | The introduction of artificial substances (usually silver iodide or dry ice) into a cloud for the purpose of either modifying its development or increasing its precipitation. [1] |
| 3068 | Coastal Chart | See chart: coast. [14] |
| 3069 | Coaxial Cable | See cable. [14] |
| 3070 | Compass North | See north: compass. [14] |
| 3071 | Compass: Boat | A small portable compass mounted in a box for convenient use in small water craft. [14] |
| 3072 | Compass: Dumb | See pelorus. [14] |
| 3073 | Constellation | Formerly a number of fixed stars grouped within an imaginary outline. Now, a region of the celestial sphere marked by arbitrary boundary lines. [14] |
| 3074 | Co-Range Line | A line through points of equal tide range. [14] |
| 3075 | Corer: Piston | A corer equipped with a piston inside the core tube that is connected to the lowering cable. When the corer penetrates the ocean bottom the stopped cable and piston, in effect, provides a suction which overcomes the frictional forces acting between the sediment and the interior wall of the coring tube. [14] |
| 3076 | Cotidal Chart | See chart. [14] |
| 3077 | Crystal Clock | See clock. [14] |
| 3078 | Cumulus Stage | The initial stage in the development of an ordinary cell thunderstorm in which rising, warm, humid air develops into a cumulus cloud. [1] |
| 3079 | Current Chart | See chart. [14] |
| 3080 | Cut: Angle Of | See angle: crossing. [14] |
| 3081 | Day: Sidereal | The duration of one rotation of the earth on its axis, with respect to the vernal equinox over the upper branch of a meridian. Because of the precession of the equinoxes, the sidereal day thus defined is slightly less than the period of rotation with respect to the stars, but the difference is less than 0.01 second. The length of the sidereal day is 24 hours of sidereal time or 23h56m04.091s of mean solar time. [14] |
| 3082 | Deep Sea Lead | See lead. [14] |
| 3083 | Density Layer | A layer of water in which density increases with depth enough to increase the buoyancy of a submarine. [14] |
| 3084 | Digital Chart | See electronic chart. [14] |
| 3085 | Discriminator | A radar circuit that produces a response which depends upon the frequency of the input signal. A transponder beacon circuit which accepts pulses of proper duration and rejects others. That part of a frequency modulation receiver which converts the modulated signals directly into audio frequency signals. [14] |
| 3086 | Dock: Graving | See dock: dry. [14] |
| 3087 | Dredging Buoy | A buoy marking the limit of an area where dredging is being performed. [14] |
| 3088 | Drift Station | A scientific station established on the ice of the arctic ocean. A term sometimes used in shoran operations to designate the ground station about which the aircraft flies. The second station is then referred to as rate station. [14] |
| 3089 | Dry Lightning | Lightning that occurs with thunderstorms that produce little, if any, appreciable precipitation that reaches the surface. [1] |
| 3090 | Due Publicity | Notification of a given action for general information through appropriate authorities within a reasonable amount of time in a suitable manner. Used in the context of the united nations' law of the sea convention. [14] |
| 3091 | Electrometeor | Visible or audible manifestation of atmospheric electricity, either corresponding to discontinuous electrical discharges (lightning, thunder) or occurring as more or less continuous phenomena (saint elmo's fire, polar aurora). [14] |
| 3092 | Envelope Edge | The fore part of an envelope. [14] |
| 3093 | Eotvos Effect | The east-west component of the movement of a ship, including the effect of marine currents, modifies the centrifugal force of the earth's rotation. It is a vertical force experienced by a body moving in an east-west direction on the rotating earth. [14] |
| 3094 | Equator: Heat | See equator: thermal. [14] |
| 3095 | Error: Random | See error: accidental. [14] |
| 3096 | Expert System | A knowledge-based computer system which utilizes artificial intelligence to do some of the inferential computation/decision making. [14] |
| 3097 | Exposure Time | The time during which a light-sensitive material is subjected to the action of light. [14] |
| 3098 | Extrapolation | The process of estimating the value of a quantity beyond the limits of known values by assuming that the rate or system of change between the last few known values continues. [14] |
| 3099 | Extreme Value | Design value of a parameter used in ultimate limit state checks, in which a structure's global behavior is intended to stay in the elastic range. NOTE Extreme events have probabilities of the order of 10^-2 per annum. [15] |
| 3100 | False Horizon | See horizon. [14] |
| 3101 | Fix: Circular | A useless fix resulting from the observations of two angles establishing as loci three coinciding circles of position. Also called revolver, or swinger. [14] |
| 3102 | Floating Dock | See dock. [14] |
| 3103 | Flux: Radiant | Power emitted, transferred or received in the form of radiation. [14] |
| 3104 | Following Sea | A sea in which the waves move in the general direction of the heading. [14] |
| 3105 | Fracture Zone | An extensive linear zone of irregular topography, mountainous or faulted, characterized by steep-sided or asymmetrical ridges, clefts, troughs, or escarpments. [14] |
| 3106 | Fringing Reef | A reef closely attached to a shore, as contrasted with a barrier reef which is separated from the shore by a lagoon. [14] |
| 3107 | Gaussin Error | See error. [14] |
| 3108 | General Chart | See chart. [14] |
| 3109 | Geodetic Data | Information concerning points established by a geodetic survey, such as descriptions for recovery, coordinate values, height above sea level, and orientation. [14] |
| 3110 | Geomorphology | A branch of both geography and geology that deals with the form of the earth, the general configuration of its surface, and the changes that take place in the evolution of land forms. [14] |
| 3111 | Grab Sampling | A random mode of collecting samples. [14] |
| 3112 | Gradient Wind | A theoretical wind that blows parallel to curved isobars or contours. [1] |
| 3113 | Graphic Scale | See scale: bar. [14] |
| 3114 | Gravity Meter | See gravimeter. [14] |
| 3115 | Harbour Chart | See chart. [14] |
| 3116 | Harbour Reach | The reach of a winding river or estuary which leads directly to the harbor. [14] |
| 3117 | Hazard Beacon | See beacon. [14] |
| 3118 | Height Finder | A stereoscopic range finder so constructed as to indicate vertical heights rather than slant range. [14] |
| 3119 | Horizon Shade | One of the pivoted coloured glasses which can be swung before the horizon glass of a sextant to regulate the intensity of light. [14] |
| 3120 | Horizon: True | In photogrammetry, a horizontal plane passing through a point of vision or perspective center. The apparent horizon approximates the true horizon only when the point of vision is very close to sea level. [14] |
| 3121 | Icelandic Low | The subpolar low-pressure area that is centered near iceland on charts that show mean sea-level pressure. [1] |
| 3122 | Indian Summer | An unseasonably warm spell with clear skies near the middle of autumn. Usually follows a substantial period of cool weather. [1] |
| 3123 | Indirect Wave | See wave. [14] |
| 3124 | Insular Shelf | A zone around an island that extends from the low water line to a depth at which there is usually a marked increase of slope towards oceanic depths. [14] |
| 3125 | Isoporic Line | A line connecting points of equal annual rate of change of a magnetic element. Also called isopor. [14] |
| 3126 | Kalman Filter | In electronics, a mathematical-statistical method for predicting a time-variable signal in the presence of disturbances. The method exploits the fact that certain characteristic parameters of the process vary slowly with time, so that a best estimate of the signal can be obtained as a function of time. [14] |
| 3127 | Landfall Buoy | See farewell buoy. [14] |
| 3128 | Layer Tinting | See layering. [14] |
| 3129 | Light: Linear | A luminous signal having perceptible length, as contrasted with a point light. [14] |
| 3130 | Light: Marine | A light intended primarily for marine navigation. [14] |
| 3131 | Line Of Force | A line indicating the direction in which a force acts, as in a magnetic field. See magnetic lines of force. [14] |
| 3132 | Line Of Nodes | The straight line connecting the two points of intersection of the orbit of a planet, planetoid, or comet and the ecliptic, or the line of intersection of the planes of the orbits of a satellite and its primary. See node. [14] |
| 3133 | Lithification | The process of induration, cementation, petrification, consolidation, and crystallization which convert magma and newly deposited sediments into rock. [14] |
| 3134 | Local Horizon | See horizon: apparent. [14] |
| 3135 | Local Transit | See transit. [14] |
| 3136 | Log: Electric | A graphic recording of the various electrical properties of a sediment or rock through which a hole has been drilled. [14] |
| 3137 | Log: Taffrail | A log consisting essentially of a rotator towed through the water by a braided log line attached to a distance registering device usually secured at the taffrail, the railing at the stern. Also called patent log. [14] |
| 3138 | Lunar Rainbow | See moonbow. [14] |
| 3139 | Make The Land | To sight and approach or reach land from seaward. [14] |
| 3140 | Map: Thematic | A map designed to demonstrate particular features or concepts. In conventional use, this term excludes topographic maps. [14] |
| 3141 | Marine Growth | Living organisms attached to an offshore structure. [15] |
| 3142 | Marsden Chart | A system introduced by marsden early in the nineteenth century for showing the distribution of meteorological data on a chart especially over the oceans. A Mercator map projection is used; the world between 90°n and 80°s being divided into marsden 'squares' each of 10 degrees latitude by 10 degrees longitude. These squares are systematically numbered to indicate position. Each square may be divided into quarter squares, or into 100 one-degree subsquares numbered from 00 to 99 to give the position to the nearest degree. [14] |
| 3143 | Measured Mile | A measured distance of one nautical mile. [14] |
| 3144 | Medimarimeter | An apparatus for recording the mean sea level. [14] |
| 3145 | Melting Point | Temperature of change from the solid to the liquid phase of a substance. It is a function of pressure. [14] |
| 3146 | Meteoric Dust | Atmospheric dust originating from meteors. [14] |
| 3147 | Middle Ground | A shallow area in otherwise deeper water with channels on both sides of it. [14] |
| 3148 | Mixed Current | See current. [14] |
| 3149 | Moirã© Effect | The effect created by transmitting light through two separate, overlapping families of parallel lines. See also inogen light. [14] |
| 3150 | Monochromatic | (Adj.). Of, or having one colour. Of, or producing light of one wavelength. [14] |
| 3151 | Nadir: Ground | The point on the ground vertically beneath the perspective center of the camera lens. [14] |
| 3152 | Natural Scale | See scale. [14] |
| 3153 | Nautical Plan | A large scale nautical chart or a large scale inset of a nautical chart. [14] |
| 3154 | Nitrogen (N2) | A colorless and odorless gas that occupies about 78 percent of dry air in the lower atmosphere. [1] |
| 3155 | Nominal Range | See range. [14] |
| 3156 | Oceanic Ridge | A long elevation of the ocean floor with either irregular or smooth topography and steep sides, often separating ocean basins. [14] |
| 3157 | Off Soundings | Said of a vessel navigating beyond the 100-fathom line. In earlier times, said of a vessel in water deeper than could be sounded with the hand lead. [14] |
| 3158 | Open Pack Ice | Floes seldom in contact with many leads and pools. Ice concentration 4/10th to 9/10th. [14] |
| 3159 | Open Traverse | See traverse. [14] |
| 3160 | Origin: False | See coordinates: false. [14] |
| 3161 | Oropesa Sweep | Towed wire used for sweeping sea bottom when surveying shoals or wrecks. It consists of a wire running from the stern of the vessel and held out on the water by an otter which also pulls down against a towed float. The amount of wire between float and otter determines the depth of the outer end of the sweep. The inner end of the sweep is held to the required depth and in line with the stern of the vessel by a kite. [14] |
| 3162 | Orthophotomap | A photomap made from an assembly of orthophotographs. It may incorporate special cartographic treatment, photographic edge enhancement, colour separation, or a combination of these. [14] |
| 3163 | Parantiselena | Photometeor of the halo family, analogous to the paranthelion, the luminary being the moon. [14] |
| 3164 | Pilot Station | The office or headquarters of pilots; the place where the services of a pilot may be obtained. [14] |
| 3165 | Polar Bearing | See bearing. [14] |
| 3166 | Port Handbook | A handbook for a specific port. [14] |
| 3167 | Primary Radar | See radar. [14] |
| 3168 | Print: Ozalid | A photographic contact print developed by a dry diazo process. The process produces a positive from a positive image or a negative from a negative image. [14] |
| 3169 | Quarter Point | The fourth of the distance from one point of the compass to another, equivalent to about two degrees and forty-nine minutes. [14] |
| 3170 | Radar Bearing | See bearing. [14] |
| 3171 | Radial: Nadir | A radial from the nadir point. See nadir: photograph. [14] |
| 3172 | Radiation Fog | A major type of fog, produced over a land area when radiational cooling reduces the air temperature to or below its dew point. [14] |
| 3173 | Radio Horizon | The line at which direct rays from a transmitting antenna become tangent to the earth's surface. Its distance from the transmitting antenna is greater than that of the visible horizon, and increases with decreasing frequency. [14] |
| 3174 | Radio Wave(S) | See wave. [14] |
| 3175 | Ratio Of Rise | The ratio of the height of tide at two places. [14] |
| 3176 | Relative Wind | For a moving object, wind vector relative to this object. Also called apparent wind. See true wind. [14] |
| 3177 | Repeatability | See repeatable accuracy. [14] |
| 3178 | Return Stroke | The luminous lightning stroke that propagates upward from the earth to the base of a cloud. [1] |
| 3179 | River Harbour | A harbor which lies on the banks of a river. [14] |
| 3180 | Rod: Sounding | See sounding pole. [14] |
| 3181 | Rodded Points | Points where the rod was actually held, as opposed to points sketched in between. [14] |
| 3182 | Roentgen Rays | See x-rays. [14] |
| 3183 | Sailing Chart | See under chart. [14] |
| 3184 | Sallying Ship | Producing rolling motion of a vessel by the running in unison of a group from side to side. This is usually done to help float a vessel which is aground or to assist it to make headway when it is beset by ice. [14] |
| 3185 | Scale: Border | A scale drawn along the border of chart. [14] |
| 3186 | Scale: Linear | See scale: bar. [14] |
| 3187 | Scintillation | Rapid variations, often in the form of pulsations, of the brightness of the stars or terrestrial light sources. [14] |
| 3188 | Sediment Core | See core. [14] |
| 3189 | Sediment Trap | A device used to measure the rate and amount of sedimentation in a location. [14] |
| 3190 | Sedimentation | The process of breakup and separation of particles from the parent rock, their transportation, deposition, and consolidation into another rock. [14] |
| 3191 | Sedimentology | The science concerned with the description, classification, origin, and interpretation of sediments and sedimentary rock. [14] |
| 3192 | Sensible Heat | The heat we can feel and measure with a thermometer. [1] |
| 3193 | Sextant Chart | See circle sheet. [14] |
| 3194 | Sextant Error | See error. [14] |
| 3195 | Sextant: Gyro | A sextant provided with a gyroscope to indicate the horizontal. [14] |
| 3196 | Siberian High | A strong, shallow area of high pressure that forms over siberia in winter. [1] |
| 3197 | Signal: Sound | See sound signal. [14] |
| 3198 | Signal: Water | A hydrographic signal erected in shallow water. [14] |
| 3199 | Sketch Survey | See survey. [14] |
| 3200 | Solitary Wave | See wave. [14] |
| 3201 | Sonic Bearing | See bearing. [14] |
| 3202 | Sounder: Echo | See echo sounder. [14] |
| 3203 | Sounding Pole | A graduated pole or rod used for sounding in shallow water. Also called sounding rod. [14] |
| 3204 | Sounding Tube | A glass tube of small diameter, used with certain types of sounding machines in determining depth. [14] |
| 3205 | Speed: Ground | See ground speed. [14] |
| 3206 | Speed: Linear | Rate of motion in a straight line. [14] |
| 3207 | Spirit Bubble | See level: spirit. [14] |
| 3208 | Storm Warning | See warning. [14] |
| 3209 | Straight-Edge | A bar of wood, metal, etc. With one edge accurately straight for drawing straight lines in cartographic applications. [14] |
| 3210 | Stratocumulus | A low cloud, predominantly stratiform, with low, lumpy, rounded masses, often with blue sky between them. [1] |
| 3211 | Stream: Flood | See flood stream. [14] |
| 3212 | Stream: Tidal | See current: tidal. [14] |
| 3213 | Sumner Method | The establishing of a line of position from the observation of the altitude of a celestial body by assuming two latitudes (or longitudes) and calculating the longitudes (or latitudes) through which the line of position passes. [14] |
| 3214 | Sun: Apparent | The actual sun as it appears in the sky. Also called true sun. [14] |
| 3215 | Sunspot Cycle | The time interval (11.2 years) during which the number of sunspots progresses from a minimum to a maximum and decreases again to a minimum. [14] |
| 3216 | Super Typhoon | A tropical cyclone (typhoon) in the western pacific that has sustained winds of 130 knots or greater. [1] |
| 3217 | Survey: Sonar | Hydrographic survey using a sonar. [14] |
| 3218 | Swallow Float | A tubular buoy, usually made of aluminium, that can be adjusted to remain at a selected density level to drift with the motion of that water mass. The float is tracked by shipboard listening devices and current velocities can be determined. [14] |
| 3219 | Swash Channel | A channel across a bank, or among shoals. [14] |
| 3220 | Tangent Screw | A slow motion screw of a surveying instrument or sextant. [14] |
| 3221 | Target: False | See echo: false. [14] |
| 3222 | Thermal Belts | Horizontal zones of vegetation found along hillsides that are primarily the result of vertical temperature variations. [1] |
| 3223 | Thermal Layer | See thermocline. [14] |
| 3224 | Tidal Harbour | See harbor. [14] |
| 3225 | Tide Register | See gauge: tide. [14] |
| 3226 | Tide(S): Neap | The tides of decreased range occurring near the times of first and last quarter. [14] |
| 3227 | Tide: Falling | The portion of the tide cycle between high water and the following low water. Also called ebb tide. The opposite is rising tide. [14] |
| 3228 | Tide: Oceanic | The periodic rise and fall of the earth's oceans resulting from gravitational interactions between the sun, moon, and earth. [14] |
| 3229 | Tide: Partial | One of the harmonic components comprising the tide at any point. The periods of the partial tides are derived from various combinations of the angular velocities of earth, sun, moon, and stars relative to each other. See harmonic constituent. [14] |
| 3230 | Tide: Primary | That part of a tidal undulation that is the direct response to a tide-producing force. [14] |
| 3231 | Tide: Weather | See tide: windward. [14] |
| 3232 | Topoangulator | An instrument used to measure vertical angles in the principal plane of an oblique photograph. [14] |
| 3233 | Tornado Alley | A region in the great plains of the united states extending from texas and oklahoma northward into kansas and nebraska where tornadoes are most frequent. [1] |
| 3234 | Tornado Watch | A forecast issued to alert the public that tornadoes may develop within a specified area. [1] |
| 3235 | Total Eclipse | See eclipse. [14] |
| 3236 | Tracing Paper | A thin tough semitransparent paper suitable for making tracings of drawings, or for miscellaneous use in hydrographic work, where permanence is not important or when pencil work is sufficient. [14] |
| 3237 | Track Plotter | A plotter used to plot the track or course of a craft. [14] |
| 3238 | Training Wall | A wall, bank, or jetty, often submerged, built to direct or confine the flow of a river or tidal current. [14] |
| 3239 | Translocation | A method to improve the accuracy of satellite positioning by simultaneously using several receivers. One receiver is deployed on a known position to obtain corrections required to match the known position and that derived from satellite signals. These corrections are then transmitted to the other receivers. [14] |
| 3240 | Trilateration | A method of surveying wherein the lengths of the triangle sides are measured, usually by electronic methods, and the angles are computed from the measured lengths. Compare with triangulation. [14] |
| 3241 | Tripod Signal | See signal. [14] |
| 3242 | True Meridian | See meridian. [14] |
| 3243 | Turning Basin | An enlargement of a channel for turning vessels. Also called manoeuvering basin. [14] |
| 3244 | Uplifted Reef | A coral reef exposed above water level. [14] |
| 3245 | Violent Storm | Wind with a speed between 56 and 63 knots (beaufort scale wind force 11). [14] |
| 3246 | Warning: Gale | Meteorological message intended to warn those concerned of the occurrence or expected occurrence of a wind of beaufort force 8 or 9 over a specified area. [14] |
| 3247 | Water Content | A ratio; 100 multiplied by the weight of water in a bottom sediment sample divided by the weight of the dried sample, expressed as a percentage. [14] |
| 3248 | Water Sampler | Any device for obtaining a water sample. Also called water sampling device. See water bottle. [14] |
| 3249 | Water-Parting | A summit or boundary line separating the drainage districts of two streams or coasts; a divide or watershed. [14] |
| 3250 | Wave Velocity | The speed at which the individual wave form advances. A vector quantity that specifies the speed and direction with which a sound wave travels through a medium. [14] |
| 3251 | Wave: Carrier | A radio wave used as a vehicle for conveying intelligence, generally by modulation. Also called carrier. [14] |
| 3252 | Wave: Gravity | A wave whose velocity of propagation is controlled primarily by gravity. Water waves of length greater than 2 inches are considered gravity waves. [14] |
| 3253 | Wave: Surface | A progressive gravity wave in which the disturbance (that is, the particle movement in the fluid mass as well as the surface movement) is confined to the upper limits of a body of water. Strictly speaking this term applies to those progressive gravity waves whose celerity depends only upon the wavelength. [14] |
| 3254 | Weather Shore | Shore that is to windward of a vessel. See lee shore. [14] |
| 3255 | Weather Types | Certain weather patterns categorized into similar groups. Used as an aid in weather prediction. [1] |
| 3256 | Weather Watch | A forecast indicating that atmospheric conditions are favorable for hazardous weather to occur over a particular region during a specified time period. [1] |
| 3257 | Weathered Ice | Hummocked polar ice subjected to weathering which has given the hummocks and pressure ridges a rounded form. If the weathering continues, the surface may become more and more even. [14] |
| 3258 | Weighted Mean | A value obtained by multiplying each of a series of values by its assigned weight and dividing the sum of those products by the sum of the weights. [14] |
| 3259 | Well: Plugged | A borehole which has been sealed with a plug and permanently abandoned. [14] |
| 3260 | Wind Machines | Fans placed in orchards for the purpose of mixing cold surface air with warmer air above. [1] |
| 3261 | Wind Profiler | A doppler radar capable of measuring the turbulent eddies that move with the wind. Because of this, it is able to provide a vertical picture of wind speed and wind direction. [1] |
| 3262 | Windward Tide | See tide. [14] |
| 3263 | Working Chart | See chart. [14] |
| 3264 | X-Coordinates | See coordinates: plane rectangular. [14] |
| 3265 | Y-Coordinates | See coordinates: plane rectangular. [14] |
| 3266 | Zenith Camera | A special camera so designed that its optical axis may be pointed accurately toward the zenith. It is used for the determination of astronomical positions by photographing the position of the stars. [14] |
| 3267 | Zone Meridian | The central meridian of each zone of a grid system. [14] |
| 3268 | Abnormal Value | Design value of a parameter of abnormal severity used in accidental limit state checks in which a structure is intended not to suffer complete loss of integrity [15] |
| 3269 | Absolute Error | See error. [14] |
| 3270 | Altitude: True | The apparent altitude of a celestial body after all corrections have been applied. In American terminology usually referred to as observed altitude. [14] |
| 3271 | Anaglyphic Map | See under map. [14] |
| 3272 | Anallatic Lens | A convergent lens fitted between the objective lens and the diaphragm of telescopes of instruments for direct measurements of distances between the optical center of the instrument and a graduated staff called stadia. [14] |
| 3273 | Area Clearance | The effective depth, within specified limits, obtained by a wire drag survey. [14] |
| 3274 | Ascending Node | See node. [14] |
| 3275 | Autocollimator | See collimator. [14] |
| 3276 | Axis Of Camera | A line perpendicular to the focal plane of the camera and passing through the emergent nodal point of the lens system. Also called camera axis. See nodal point. [14] |
| 3277 | Axis: Trunnion | See axis: horizontal. [14] |
| 3278 | Axis: Vertical | In a theodolite or transit, the line through the center of the instrument about which the alidade rotates. [14] |
| 3279 | Band Of Colour | See stripes (of colour) [14] |
| 3280 | Base Direction | See direction. [14] |
| 3281 | Base Terminals | The two extremes of a base line. Usually marked on a monument or metal stake buried beneath a visible surface mark. See also reference mark. [14] |
| 3282 | Beacon: Hazard | A beacon marking an obstruction or hazard. [14] |
| 3283 | Bearing Circle | A ring designed to fit snugly over a compass or compass repeater, and provided with vanes for observing bearings. A similar ring provided with means for observing azimuth of the sun is called an azimuth circle. [14] |
| 3284 | Bearing: Polar | In a system of polar or spherical coordinates, the angle formed by the intersection of the reference meridional plane and the meridional plane containing the point. [14] |
| 3285 | Bearing: Radar | A bearing obtained by radar. [14] |
| 3286 | Bearing: Radio | The angle between the apparent direction of a definite source of emission of electro-magnetic waves and a reference direction, as determined at a radio direction-finding station. [14] |
| 3287 | Bottom Current | The movement of water along the bottom of reservoirs or rivers. [2] |
| 3288 | Bottom Sampler | Any device for obtaining a bottom sample. See also corer, dredge, driver rod, grab and snapper. [14] |
| 3289 | Boundary Layer | The layer of fluid in the immediate vicinity of a bounding surface. It is the layer in which frictional forces are not negligible. [14] |
| 3290 | Bubble Sextant | See sextant. [14] |
| 3291 | Buoy: Cardinal | A buoy used to indicate that the best navigable water is to be found in one particular of the quadrants that are bounded by the four bearings nw, ne, se and sw taken from the position of the mark. [14] |
| 3292 | Buoyant Beacon | See articulated light. [14] |
| 3293 | Cable: Coaxial | A transmission cable consisting of two concentric conductors insulated from each other. [14] |
| 3294 | Camera: Aerial | A camera specially designed for use in aircraft. [14] |
| 3295 | Capillary Wave | See wave. [14] |
| 3296 | Careening Grid | A structure in the intertidal zone serving as a support for vessels at low stages of the tide to permit work on the exposed portion of the vessel's hull. Also called gridiron. [14] |
| 3297 | Chart: Cotidal | A chart showing cotidal lines. [14] |
| 3298 | Chart: Current | A chart on which current data are graphically depicted. [14] |
| 3299 | Chart: Fishery | A chart with additional details required for the exploitation of marine natural resources. [14] |
| 3300 | Chart: General | A nautical chart intended for offshore coastwise navigation. [14] |
| 3301 | Chart: Harbour | A nautical chart intended for navigation and anchorage in harbors and small waterways. [14] |
| 3302 | Chart: Sailing | A small scale nautical chart for offshore navigation. [14] |
| 3303 | Chart: Working | In hydrographic survey, a working document (chart or projection) by means of which a survey programme can be broadly planned. [14] |
| 3304 | Circular Level | See level: spirit. [14] |
| 3305 | Civil Twilight | See twilight. [14] |
| 3306 | Clamping Error | See error. [14] |
| 3307 | Clear Sweeping | A form of bar sweeping. A sweep, set at a predetermined depth, and passed over an area to ensure that no obstructions have been missed. [14] |
| 3308 | Clearing Marks | Selected marks, natural or otherwise, used to help vessels keep clear of dangers. [14] |
| 3309 | Clock: Crystal | A precision clock essentially consisting of a generator of constant frequency controlled by a resonator made of quartz crystal with suitable methods for producing continuous rotation to operate time-indicating and related mechanisms. Also called quartz clock. [14] |
| 3310 | Close Pack Ice | Pack ice composed of floes mostly in contact, such that navigation becomes difficult even for specially constructed vessels. Ice concentration 7/10th to 9/10th. [14] |
| 3311 | Coastal Survey | See survey. [14] |
| 3312 | Cocurrent Line | A line through places having the same tidal current hour. [14] |
| 3313 | Compass Course | See course. [14] |
| 3314 | Compass Points | The 32 divisions of a compass, at intervals of 11°1/4. [14] |
| 3315 | Compass: Astro | An instrument which, when oriented to the horizontal and to the celestial sphere, indicates a horizontal reference direction relative to the earth. This compass is designed primarily for the observation of celestial bodies to determine the orientation of an aircraft relative to the azimuth of a celestial body. [14] |
| 3316 | Composite Path | A wave track which lies partly over land and partly over water. [14] |
| 3317 | Constant Error | See error. [14] |
| 3318 | Contour: Depth | See depth curve. [14] |
| 3319 | Control: Basic | See control. [14] |
| 3320 | Control: Minor | See control: photogrammetric. [14] |
| 3321 | Correspondence | In stereoscopy, the condition that exists when corresponding images on a pair of photographs lie in the same epipolar plane; the absence of y-parallax. [14] |
| 3322 | Co-Tidal Chart | A chart of a major harmonic constituent (or of a semi-diurnal tide) constructed to illustrate the propagation patterns and to assist in the interpolation of tidal conditions and datum assessment at locations where no observations exist (especially offshore). Now frequently replaced by numerical modelling. [16] |
| 3323 | Country Breeze | A light breeze that blows into a city from the surrounding countryside. It is best observed on clear nights when the urban heat island is most pronounced. [1] |
| 3324 | Cross Bearings | Two or more bearings used as intersecting lines of position for fixing the position of a craft. [14] |
| 3325 | Crossing Angle | See angle. [14] |
| 3326 | Current: Drift | A wide, slow-moving ocean current principally caused by winds. [14] |
| 3327 | Current: Earth | See current(s): telluric. [14] |
| 3328 | Current: Flood | See flood stream. [14] |
| 3329 | Current: Mixed | The type of tidal current characterized by a conspicuous difference in speed and duration between the two flood currents or two ebb currents occurring each tidal day. [14] |
| 3330 | Current: Surge | The coastal current influenced by remote waves. [14] |
| 3331 | Current: Tidal | The alternating horizontal movement of water associated with the rise and fall of the tide caused by tide-producing forces. Also called tidal stream. [14] |
| 3332 | Cycloidal Wave | See wave. [14] |
| 3333 | Damped Wave(S) | See wave. [14] |
| 3334 | Danger Bearing | See bearing. [14] |
| 3335 | Dangerous Rock | A sunken rock of a small area (pinnacle), at such a depth as to be considered dangerous to surface navigation. [14] |
| 3336 | Data Retrieval | The extraction of data which meet certain criteria from a file or data bank. [14] |
| 3337 | Data Telemetry | Measuring a quantity, and transmitting the measured value to a distant station where further processing takes place. [14] |
| 3338 | Depressed Pole | See pole. [14] |
| 3339 | Depth: Charted | The vertical distance from the chart datum to the bottom. [14] |
| 3340 | Dike (Or Dyke) | An artificial ditch to hold, or control the flow of water. An artificial embankment to contain or hold back water. In geology, a tabular body of igneous rock molded from molten rock within a fissure. [14] |
| 3341 | Dioptric Light | See light. [14] |
| 3342 | Dock: Floating | A form of dry dock consisting of a floating structure of one or more sections which can be partly submerged by controlled flooding to receive a vessel, then raised by pumping out the water so that the vessel's bottom can be exposed. [14] |
| 3343 | Dolphin Beacon | A minor light structure consisting of a number of piles driven into the bottom in a geometric or random pattern and drawn together, with a light mounted at the top. [14] |
| 3344 | Doppler Effect | The apparent change in wavelength, and therefore in frequency of radiant energy, when the distance between the source and the observer or receiver is changing. This effect is exploited in underwater acoustics and satellite positioning. [14] |
| 3345 | Drift Ice Foot | See ramp. [14] |
| 3346 | Drift Sounding | See sounding. [14] |
| 3347 | Dumping Ground | A sea area where dredged material or other potentially more harmful material e.g. Explosives, chemical waste, is deliberately deposited. See also spoil ground. [14] |
| 3348 | Dutchman'S Log | See log. [14] |
| 3349 | Earth Inductor | An electric instrument used to measure the inclination of the earth's magnetic field. [14] |
| 3350 | Earth'S Mantle | The relatively plastic region between the crust and core of the earth. Also called asthenosphere. [14] |
| 3351 | Echo(Es): Side | See echo(es): false. [14] |
| 3352 | Eclipse: Lunar | An eclipse of the moon. When the moon enters the shadow of the earth, it appears eclipsed to an observer on the earth. [14] |
| 3353 | Eclipse: Solar | An eclipse of the sun. When the moon passes between the sun and the earth, the sun appears eclipsed to an observer in the moon's shadow. [14] |
| 3354 | Eclipse: Total | An eclipse in which the entire source of light is obscured. [14] |
| 3355 | Eotvos Balance | See torsion balance. [14] |
| 3356 | Epipolar Plane | Any plane which contains the epipoles; therefore any plane containing the air base. Also called basal plane. [14] |
| 3357 | Equiphase Zone | See zone. [14] |
| 3358 | Error: Closing | See error of closure. [14] |
| 3359 | Error: Gaussin | Deviation of a magnetic compass due to transient magnetism which remains in a vessel's structure for short periods after the inducing force has been removed. This error usually appears after a vessel has been on the same heading for a considerable time. [14] |
| 3360 | Error: Heeling | The change in the deviation of a magnetic compass when a craft heels, due to the change in the position of the magnetic influences of the craft relative to the earth's magnetic field and to the compass. [14] |
| 3361 | Error: Regular | See error: systematic. [14] |
| 3362 | Error: Sextant | The error in the reading of a sextant, due either to lack of proper adjustment or to imperfection of manufacture. [14] |
| 3363 | Error: Station | See deflection of the vertical. [14] |
| 3364 | European Datum | Constituted by the international spheroid located at the potsdam origin. [14] |
| 3365 | Field Position | See position. [14] |
| 3366 | Fish Trap Buoy | A buoy marking the limits of a fish trap area. [14] |
| 3367 | Flux: Luminous | Quantity, characteristic of radiant flux which expresses its capacity to produce a luminous sensation. [14] |
| 3368 | Focal Distance | See focal length. [14] |
| 3369 | Fog: Advection | Fog which forms in the lower part of a moist air mass which moves over a colder surface. [14] |
| 3370 | Following Wind | Wind blowing in the general direction of a vessel's course. [14] |
| 3371 | Free Gyroscope | See gyro: free. [14] |
| 3372 | Generalisation | The omission of less important detail when compiling a chart. Its purpose is to avoid overloading charts where space is limited. [14] |
| 3373 | Geoengineering | The use of global scale technology fixes to mitigate climate changes. [1] |
| 3374 | Glacier Tongue | Projecting seaward extension of glacier, usually afloat. [14] |
| 3375 | Global Climate | Climate of the entire globe. [1] |
| 3376 | Gnomonic Chart | See chart. [14] |
| 3377 | Gravity Coring | A method to obtain cores by bottom penetration solely as a result of gravity. [14] |
| 3378 | Grid Direction | See direction. [14] |
| 3379 | Grid Variation | See variation. [14] |
| 3380 | Ground Effects | Influence exerted by the ground on the propagation of electromagnetic waves. [14] |
| 3381 | Group Velocity | The velocity of a wave disturbance as a whole, i.e., of an entire group of component simple harmonic waves. [14] |
| 3382 | Harbour Master | A local official who has charge of mooring and berthing of vessels, collecting harbor fees, etc. [14] |
| 3383 | Harbour: Inner | The part of a harbor more remote from the sea, as contrasted with the outer harbor. These expressions are usually used only in a harbor that is clearly divided into two parts, as by a narrow passageway or man-made structures. The inner harbor generally has additional protection and is often the principal berthing area. [14] |
| 3384 | Harbour: Outer | The part of a harbor towards the sea, through which a vessel enters the inner harbor. [14] |
| 3385 | Harbour: Tidal | A harbor affected by the tides, in distinction from a harbor in which the water level is maintained by caissons or gates. [14] |
| 3386 | Heat Lightning | Distant lightning that illuminates the sky but is too far away for its thunder to be heard. [1] |
| 3387 | Heat Lightning | Lightning flash at a distance which may be observed as a short illumination of the sky or of a cloud, close to the horizon. [14] |
| 3388 | Horizon Mirror | The mirror part of the horizon glass. The expression is sometimes used somewhat loosely to refer to the horizon glass. [14] |
| 3389 | Horizon: False | A line resembling the apparent horizon but above or below it. [14] |
| 3390 | Horizon: Radio | See radio. [14] |
| 3391 | Image: Virtual | An image that cannot be shown on a surface but is visible, as in a mirror. [14] |
| 3392 | Ingoing Stream | See flood stream. [14] |
| 3393 | Intended Track | See track. [14] |
| 3394 | Intervalometer | A timing device for automatically operating the shutter of a camera at selected intervals. [14] |
| 3395 | Inverted Image | See image. [14] |
| 3396 | Island Harbour | See under harbor. [14] |
| 3397 | Isopycnic Line | A line connecting points of equal density. Also called isopycnic. [14] |
| 3398 | Katabatic Wind | An offshore wind produced by cold air draining from high ground by convection. The cold air replaces the lighter warm air which is rising over the sea. [14] |
| 3399 | Kinetic Energy | The energy within a body that is a result of its motion. [1] |
| 3400 | Lateral System | A buoyage system generally used for well defined channels; buoyage marks indicate the position of dangers in relation to the route to be followed by mariners in their vicinity. [14] |
| 3401 | Latitude Scale | See scale. [14] |
| 3402 | Lead: Deep Sea | A heavy sounding lead the weight of which may be varied from about 15 to over 50 kilos depending on the depths to be sounded. Also called dipsey lead. [14] |
| 3403 | Lead: Sounding | A lead attached to a line used for measuring the depth of water. Also called plummet. [14] |
| 3404 | Level: Tilting | See levelling instrument: tilting level. [14] |
| 3405 | Line Of Levels | A continuous series of measured differences of elevation. [14] |
| 3406 | Liquid Compass | See compass. [14] |
| 3407 | Little Ice Age | The period from about 1550 to 1850 when average temperatures over Europe were lower, and alpine glaciers increased in size and advanced down mountain canyons. [1] |
| 3408 | Louver Shutter | See shutter. [14] |
| 3409 | Low Water Mark | The intersection of the plane of low water with the shore. The line along a coast, or beach, to which the sea recedes at low water. Also called low water line. [14] |
| 3410 | Lunar Distance | The angle, at an observer on the earth, between the moon and another celestial body. This was the basis of a method formerly used to determine longitude at sea. [14] |
| 3411 | Magnetic Chart | See chart. [14] |
| 3412 | Magnetic Range | See range. [14] |
| 3413 | Magnetic Storm | A disturbance in the earth's magnetic field, associated with abnormal solar activity, and capable of seriously affecting both radio and wire transmission. [14] |
| 3414 | Manuscript Map | See map. [14] |
| 3415 | Map: Cadastral | A map showing the boundaries of subdivision of land, usually with the bearings and lengths thereof and the area of individual tracts, for purposes of describing and recording ownership. A cadastral map may also show culture, drainage, and other features relating to the value and use of land. See also plat. [14] |
| 3416 | Marine Biology | See biology. [14] |
| 3417 | Marine Climate | A climate controlled largely by the ocean. The ocean's influence keeps winters relatively mild and summers cool. [1] |
| 3418 | Marine Railway | A track, cradle, and winding mechanism for hauling vessels out of the water so that the hull can be exposed as in a dry dock. This is also called a patent slip in British terminology. [14] |
| 3419 | Mark: Geodetic | See mark. [14] |
| 3420 | Master Station | The governing station of two or more synchronized transmitting stations. Often shortened to master. See slave station. [14] |
| 3421 | Matthews Table | An echo sounding correction table. [14] |
| 3422 | Mean Neap Rise | The height of mean high waters neaps above the chart datum. Also called neap rise. [14] |
| 3423 | Meridian Angle | Angular distance east or west of the local celestial meridian; the arc of the celestial equator, or the angle at the celestial pole, between the upper branch of the local celestial meridian and the hour circle of a celestial body, measured eastward or westward from the local celestial meridian through 180°, and labelled e or w to indicate the direction of measurement. See hour angle. [14] |
| 3424 | Meridian: Grid | One of the grid lines extending in a grid north-south direction. [14] |
| 3425 | Meridian: True | A meridian. The expression is used to distinguish the great circle through the geographical poles from magnetic meridian, compass meridian, or grid meridian. [14] |
| 3426 | Meridian: Zone | The meridian used for reckoning zone time. [14] |
| 3427 | Microprocessor | Component of a data processing device made up of microcircuits integrated on a single chip. [14] |
| 3428 | Mobile Station | A radiolocation station intended to be used at unspecified points. As opposed to fixed station. [14] |
| 3429 | Mountain Chain | A complexity of several mountain ranges. [14] |
| 3430 | Noon: Apparent | Twelve o'clock apparent time. [14] |
| 3431 | North: Compass | The direction north as indicated by a magnetic compass. [14] |
| 3432 | Notch (Or Gap) | A narrow passage between two elevations, as mountains; a deep close pass; a defile. [14] |
| 3433 | Open Roadstead | A roadstead with relatively little protection from the sea. [14] |
| 3434 | Optical Square | A small hand instrument used to set off a right angle. [14] |
| 3435 | Original Chart | See chart. [14] |
| 3436 | Orthochromatic | (Adj.). Said of photographic surfaces sensitive to ultra-violet, blue, yellow, green and orange rays. Insensitive to red rays. [14] |
| 3437 | Paleomagnetism | Remanent magnetism produced by the earth's field when a material was initially formed. [14] |
| 3438 | Parallel Plate | An optical disk with optically flat, parallel surfaces; used especially in optical micrometers. [14] |
| 3439 | Passive System | A system which records energy emitted or reflected but does not produce or transmit energy of its own. [14] |
| 3440 | Perigean Tides | See tide. [14] |
| 3441 | Periodic Error | See error. [14] |
| 3442 | Phase Velocity | Velocity, measured over a short time period, at which a particular wave crest is propagated a medium. [14] |
| 3443 | Photoengraving | A process by which photographs are reproduced on printing plates especially one in which the reproduction is in relief: opposed to photogravure. A plate so made. A print from such a plate. [14] |
| 3444 | Planning Chart | A chart designed for use in planning voyages or flight operations or investigating areas of marine or aviation activities. [14] |
| 3445 | Plotting Board | A stiff transparent polar coordinate plotting sheet for tracking other vessels and aircraft and solving problems involving relative movement. [14] |
| 3446 | Pocket Compass | See compass. [14] |
| 3447 | Poincarã© Wave | A long period gravity wave. The superposition of incident and reflected plane waves (Sverdrup waves) such that the composite wave fronts are perpendicular to the coast with a set of nodal lines normal to the wave fronts. The term is used in tidal analysis to study ocean tides and tides in open seas and gulfs. [14] |
| 3448 | Point Of Aries | See equinox. [14] |
| 3449 | Pole: Elevated | The celestial pole above the horizon, agreeing in name with the latitude. [14] |
| 3450 | Pole: Magnetic | See magnetic pole. [14] |
| 3451 | Port Authority | The entity responsible for administration and maintenance of harbor facilities. [14] |
| 3452 | Pressure Gauge | See gauge. [14] |
| 3453 | Pressure Plate | In photography, a flat plate (usually of metal but frequently of glass or other substance) which, by means of mechanical force, presses film into contact with the focal-plane plate of a camera. [14] |
| 3454 | Pressure Ridge | A ridge or wall of hummocked ice where one floe has been pressed against another. [14] |
| 3455 | Primary Circle | See primary great circle. [14] |
| 3456 | Principal Axis | See axis of lens. [14] |
| 3457 | Print: Contact | A photographic print made from either a negative or a positive in contact with a sensitized material. [14] |
| 3458 | Proof Plotting | An advanced copy of a map or chart produced by a plotter to check the design and registration, and to detect and correct errors before final printing. [14] |
| 3459 | Quartering Sea | Waves moving in a direction approximately 45° from a vessel's heading, striking the vessel on the quarter. [14] |
| 3460 | Radargrammetry | The process of obtaining reliable measurements in bi- and three-dimensional image processing by means of radar. [14] |
| 3461 | Radio Receiver | Equipment for receiving radio signals and converting them into usable form. [14] |
| 3462 | Radio Sonobuoy | See sonobuoy. [14] |
| 3463 | Radio Spectrum | The range of electromagnetic radiations useful for communication by radio (approximately 10 kilohertz to 300,000 megahertz). [14] |
| 3464 | Raise The Land | (v.t.). To sight land by approaching to the point where it appears above the horizon. [14] |
| 3465 | Range Light(S) | See light. [14] |
| 3466 | Range: Nominal | The luminous range of a light in a homogenous atmosphere in which the meteorological visibility is 10 sea miles. [14] |
| 3467 | Reflected Wave | See wave. [14] |
| 3468 | Refracted Wave | See wave. [14] |
| 3469 | Rocket Station | A life saving station equipped with line-carrying rocket apparatus. [14] |
| 3470 | Rod: Levelling | See levelling rod. [14] |
| 3471 | Rollers: Blind | See blind rollers. [14] |
| 3472 | Rossby Wave(S) | Ignoring friction or depth changes; if a parcel of water with no initial relative vorticity (i.e. No rotation) is moved northward, as f (the Coriolis parameter) increases the parcel will gain negative relative vorticity and will circulate clockwise. The Coriolis force will be greater on the poleward side of the parcel than on the equatorward side and hence the parcel will be subjected to a net south-ward restoring force. This force will push the parcel south of the latitude of zero relative vorticity overshoots and the circulation becomes counterclockwise. Due to the Coriolis variation the parcel will now experience a northward restoring force. Thus the variation of f provides a restoring force (in the horizontal plane) allowing oscillation to occur just as the effect of gravity does (vertically) for surface or internal waves. In reality rossby waves are complicated by depth variations and frictional effects. [14] |
| 3473 | Rotary Current | See current. [14] |
| 3474 | Rotating Light | See light. [14] |
| 3475 | Rotating Prism | See dove prism. [14] |
| 3476 | Routeing Guide | A document designed to be used in conjunction with nautical charts and other nautical publications in areas where complex routing systems have been established by the IMO. [14] |
| 3477 | Running Survey | See survey. [14] |
| 3478 | Sailing: Plane | A sailing in which the earth or a small part of it is considered a plane. [14] |
| 3479 | Santa Ana Wind | A warm, dry wind that blows into southern california from the east off the elevated desert plateau. Its warmth is derived from compressional heating. [1] |
| 3480 | Scale: Graphic | See scale: bar. [14] |
| 3481 | Seabed Sampler | A device used to obtain samples of the sea floor. [14] |
| 3482 | Seamount Chain | Several seamounts in a line with bases separated by a relatively flat sea floor. [14] |
| 3483 | Seamount Group | Several closely spaced seamounts not in a line. [14] |
| 3484 | Seamount Range | Several seamounts having connected bases and aligned along a ridge or rise. [14] |
| 3485 | Shear Strength | The internal resistance of a body to shear stress. [14] |
| 3486 | Signal Station | A place on shore from which signals are made to ships at sea. [14] |
| 3487 | Signal: Survey | A natural or artificial object or structure whose horizontal and sometimes vertical position is obtained by surveying methods. Survey signals are given special designation according to the kind of survey in which they are determined, or which they may later serve. [14] |
| 3488 | Signal: Tripod | A three-legged triangulation signal. It is usually constructed in such a manner that an observer can set up his theodolite and make observations without moving any of the structure. [14] |
| 3489 | Solar Parallax | See parallax. [14] |
| 3490 | Sounding: Echo | See echo sounding. [14] |
| 3491 | Sounding: Wire | Sounding with a sounding machine. To obtain a vertical wire sounding the ship or boat must be stopped while the wire is running out. [14] |
| 3492 | Speed Of Sound | The speed of propagation of sound waves. [14] |
| 3493 | Spherical Buoy | See buoy. [14] |
| 3494 | Spherical Wave | See wave. [14] |
| 3495 | Spring Tide(S) | See tide. [14] |
| 3496 | Stepped Leader | An initial discharge of electrons that proceeds intermittently toward the ground in a series of steps in a cloud- to-ground lightning stroke. [1] |
| 3497 | Stratification | The state of a fluid that consists of two or more horizontal layers arranged according to their density. [14] |
| 3498 | Stream Current | See current. [14] |
| 3499 | Stream: Rotary | See current: rotary. [14] |
| 3500 | Striding Level | See level. [14] |
| 3501 | Sublunar Point | The geographical position of the moon. That point on the surface of the earth at which the moon is in the zenith at a specified time. See sub-point. [14] |
| 3502 | Submarine Bell | A bell whose signal is transmitted through water. [14] |
| 3503 | Submerged Rock | A rock covered at the chart sounding datum and considered to be potentially dangerous to navigation. [14] |
| 3504 | Subsolar Point | The geographical position of the sun; that point on the earth at which the sun is in the zenith at a specified time. [14] |
| 3505 | Substitute Map | See map. [14] |
| 3506 | Sugar Loaf Sea | Waves that rise into sugar loaf shapes, with little wind, possibly resulting from intersecting waves. [14] |
| 3507 | Survey Station | See station. [14] |
| 3508 | Survey: Aerial | A survey using aerial photographs as part of the surveying operation; also the taking of aerial photographs for surveying purposes. [14] |
| 3509 | Survey: Ground | A survey made by ground methods, as distinguished from an aerial survey. A ground survey may or may not include the use of photographs. [14] |
| 3510 | Survey: Sketch | A hydrographic survey made (due to lack of time or facilities) to a lower degree of accuracy and detail than the chosen scale would normally indicate. [14] |
| 3511 | Tagline Survey | See survey. [14] |
| 3512 | Tandem Control | In hydrographic survey, a system of obtaining two or more adjacent sounding lines run simultaneously and controlled by one ship, the other ships, or launches being merely referenced to it. [14] |
| 3513 | Tape Stretcher | A mechanical device which facilitates holding a tape at a prescribed tension and in a prescribed position. [14] |
| 3514 | Tape: Standard | See reference tape. [14] |
| 3515 | Telegraph Buoy | A buoy used to mark the position of a submarine telegraph cable. [14] |
| 3516 | Tidal Light(S) | See light. [14] |
| 3517 | Tidal Movement | The movement which includes both the vertical rise and fall of the tide, and the horizontal flow of the tidal currents. This movement is associated with the astronomical tide-producing fores of the moon and sun acting upon the rotating earth. [14] |
| 3518 | Tidal Theories | The different theories trying to describe the tidal phenomena. [14] |
| 3519 | Tide: Analysis | The mathematical processes by which the observed tide or tidal current are analyzed to obtain constituents and statistics. [14] |
| 3520 | Tide: Compound | A tide constituent with a speed equal to the sum or difference of the speeds of two or more basic constituents. Compound tides usually occur in shallow water regions. See shallow water constituent. [14] |
| 3521 | Tide: Windward | A tidal current setting to windward. Also called weather tide. [14] |
| 3522 | Tilt: Relative | The angular relationship between two overlapping vertical photographs with no reference to an established datum. [14] |
| 3523 | Time: Sidereal | Time measured by the apparent diurnal rotation of the (true) vernal equinox. It is counted from 0 hour, when the vernal equinox is on the meridian, through 24 hours. Naming the meridian of reference is essential to its complete identification. [14] |
| 3524 | Time: Standard | A variation of zone time adapted for use on or near land, with irregular but well-defined zone limits. [14] |
| 3525 | Tornadogenesis | The process by which a tornado forms. [1] |
| 3526 | Transit: Local | The apparent passage of a celestial body across the meridian of the observer. See also meridian transit. [14] |
| 3527 | Traverse Point | See turning point. [14] |
| 3528 | Traverse Table | A table giving relative values of various parts of plane right triangles, for use in solving such triangles, particularly in connection with various sailings. [14] |
| 3529 | Tribrach Plate | A demountable, three-armed plate which is attached to an instrument stand or survey tower and on which the bottoms of the footscrews of the instrument rest in milled grooves. [14] |
| 3530 | Trough Compass | See declinatoire. [14] |
| 3531 | Turbulent Flow | A flow characterized by turbulence. [14] |
| 3532 | Twilight Stars | Stars suitably placed for astronomical observation during morning or evening twilight. [14] |
| 3533 | Underwater Ice | See anchor ice. [14] |
| 3534 | Valley: Median | See median valley. [14] |
| 3535 | Vanishing Line | In photogrammetry, the straight line on a photograph upon which lie all the vanishing points of all systems of parallel lines parallel to one plane. [14] |
| 3536 | Visible Region | Radiation with a wavelength between 0.4 and 0.7 mm. See visible radiation. [1] |
| 3537 | Warning: Storm | Meteorological message intended to warn those concerned of the occurrence or expected occurrence of a wind of beaufort force 10 or 11 over a specified area. More generally, forecast of severe weather conditions. [14] |
| 3538 | Wave Direction | The direction from which waves are moving. [14] |
| 3539 | Wave Steepness | Characteristic of individual waves defined as wave height divided by wavelength [14] |
| 3540 | Wave(S): Radio | Electromagnetic waves of frequencies generally higher than those of audible sound waves but lower than those of heat and light waves. Also called hertzian waves. [14] |
| 3541 | Wave: Cellular | System of surface waves in which the oscillation of water is limited as by solid boundaries. The period is the same in adjacent cells. [14] |
| 3542 | Wave: Indirect | Any wave which arrives by an indirect path having undergone an abrupt change of direction by refraction or reflection. See wave: sky. [14] |
| 3543 | Wave: Internal | A wave that occurs within a fluid whose density changes with depth, either abruptly at a sharp surface of discontinuity (an interface) or gradually. Also called boundary wave. [14] |
| 3544 | Wave: Pressure | See pressure wave. [14] |
| 3545 | Wave: Solitary | A wave of translation consisting of a single crest rising above the undisturbed liquid level, without any accompanying trough, in contrast with a wave train. [14] |
| 3546 | Weather Signal | See signal. [14] |
| 3547 | Well: Deviated | A borehole drilled at an oblique angle to evaluate or remove oil or natural gas reserves not directly below the drilling structure. [14] |
| 3548 | Wire: Sounding | See sounding. [14] |
| 3549 | Year: Sidereal | The period of one apparent revolution of the earth around the sun, with respect to a fixed point, or a distant star devoid of proper motion, being 365 days, 6 hours, 9 minutes, and 9.5 seconds in 1900 and increasing at the rate of 0.0001 second annually. [14] |
| 3550 | Zodiacal Light | White or yellowish light which spreads out, in the night sky, more or less along the zodiac from the horizon on the side on which the sun is hidden. It is observed when the sky is sufficiently dark and the atmosphere sufficiently clear. [14] |
| 3551 | Achromatic Lens | A compound lens that has been partly corrected for chromatic aberration. Such a lens is customarily made to bring green and red-light rays to approximately the same point focus. Also called achromat. See aberration of light. [14] |
| 3552 | Adjacent Coasts | The coasts lying either side of the land boundary between two adjoining states. [14] |
| 3553 | Air Photography | See photography: aerial. [14] |
| 3554 | Aluminium Sheet | An aluminium-mounted paper sheet occasionally used for boat-sheets, smooth sheets, or plane table boards. [14] |
| 3555 | Angle: Crossing | The angle at which two lines of position intersect. Also called angle of cut. [14] |
| 3556 | Angle: Masthead | See masthead angle. [14] |
| 3557 | Annual Parallax | See parallax. [14] |
| 3558 | Annular Eclipse | See eclipse. [14] |
| 3559 | Apogean Tide(S) | See under tide. [14] |
| 3560 | Aurora Borealis | Aurora of the northern hemisphere. [14] |
| 3561 | Axis Of Channel | The center line of a channel. See also talweg. [14] |
| 3562 | Axis: Principal | See axis of lens. [14] |
| 3563 | Azimuth Diagram | A diagram for obtaining graphically rather than by computation the azimuths of observed celestial bodies. [14] |
| 3564 | Bathythermogram | The record of temperature versus depth made by a bathythermograph. Rarely used. [14] |
| 3565 | Bearing: Danger | The maximum or minimum bearing of a point for safe passage of an offlying danger. [14] |
| 3566 | Biology: Marine | The study of the life, history and ecology of marine and brackish water plants and animals. [14] |
| 3567 | Bioluminescence | The emission of light by living organisms. See also noctiluca. [14] |
| 3568 | Bissextile Year | See year: civil. [14] |
| 3569 | Border Of Chart | The neatline defining the limits of the area charted. [14] |
| 3570 | Bottom Friction | The force resulting from the interaction between the ocean bottom and water particle motion over it. [14] |
| 3571 | Bottom Friction | The friction generated by the bathymetry. [19] |
| 3572 | Bottom Profiler | An echo sounder for precision surveys of the sea bottom surface. [14] |
| 3573 | Bottom Sampling | The process of collecting bottom samples. [14] |
| 3574 | Bridge: Bascule | A counterpoise bridge rotated in a vertical plane about an axis at one or both ends. Also called balance bridge. [14] |
| 3575 | Buoy: Automatic | See automatic floating station. [14] |
| 3576 | Cardinal System | A buoyage system generally used to indicate dangers where the coast is flanked by numerous islands, rocks and shoals as well as to indicate dangers in the open sea. In this system the bearing (true) of the mark from the danger is indicated to the nearest cardinal point. A system of buoyage in which the aids are assigned shape, colour, and number distinction in accordance with location relative to the nearest obstruction. The cardinal points delineate the sectors for buoy location. [14] |
| 3577 | Catoptric Light | See light. [14] |
| 3578 | Celestial Globe | See star globe. [14] |
| 3579 | Chart Portfolio | A systematic grouping of nautical charts covering a specific geographical area. [14] |
| 3580 | Chart: Magnetic | A chart showing for an established epoch the values of such magnetic elements as variation, dip, horizontal and vertical intensity of the earth's magnetic field, and total magnetic intensity. [14] |
| 3581 | Chart: Mercator | A chart on the Mercator projection. This is the chart commonly used for marine navigation. On a Mercator chart, a rhumb line is a straight line. [14] |
| 3582 | Chart: Original | A chart which has been drawn up as a result of direct survey. [14] |
| 3583 | Closed Traverse | See traverse. [14] |
| 3584 | Coastal Current | See current. [14] |
| 3585 | Comparing Watch | See watch. [14] |
| 3586 | Compass: Master | A compass controlling one or several repeaters. [14] |
| 3587 | Compass: Pocket | A portable compass (employed in coastlining or reconnaissance survey). [14] |
| 3588 | Compass: Spirit | See compass: liquid. [14] |
| 3589 | Compass: Trough | See declinatoire. [14] |
| 3590 | Concluded Angle | See angle. [14] |
| 3591 | Constituent Day | See day. [14] |
| 3592 | Continuous Wave | See wave. [14] |
| 3593 | Control: Ground | Control established by ground surveys, as distinguished from control established by photogrammetric methods. [14] |
| 3594 | Coordinatograph | An instrument used to plot in terms of plane rectangular coordinates. It may be an integral part of a stereoscopic plotting instrument whereby the planimetric motions (x and y) of the floating mark are plotted directly. [14] |
| 3595 | Counter Current | A secondary current setting in a direction opposite to that of a main current. [14] |
| 3596 | Course: Compass | See course. [14] |
| 3597 | Current: Rotary | A tidal current that flows continually, with the direction of flow changing through 360° during a tidal cycle. Called rotary stream in British terminology. [14] |
| 3598 | Current: Stream | A narrow, deep, and fast-moving current as opposed to a relatively wide and weak drift current. [14] |
| 3599 | Danger Sounding | See sounding. [14] |
| 3600 | Dangerous Wreck | A wreck submerged at such a depth as to be considered dangerous to surface navigation. [14] |
| 3601 | Day: Mean Solar | See day: solar. [14] |
| 3602 | Deep-Sea Camera | See camera. [14] |
| 3603 | Depth: Standard | A depth below the sea surface at which water properties should be measured and reported, according to the proposal by the international association of physical oceanography in 1936. [14] |
| 3604 | Descending Node | See node. [14] |
| 3605 | Desertification | A general increase in the desert conditions of a region. [1] |
| 3606 | Deviation Table | A table of the deviation of a magnetic compass on various headings, magnetic or compass. [14] |
| 3607 | Dipping Compass | See dip circle. [14] |
| 3608 | Direction: Base | In photogrammetry, the direction of the vertical plane containing the air base which might be expressed as a bearing or an azimuth. [14] |
| 3609 | Direction: Grid | Horizontal direction expressed as angular distance from grid north. [14] |
| 3610 | Dracontic Month | See month: nodical. [14] |
| 3611 | Echo(Es): False | In echo sounding, echoes caused by a foreign matter such as kelp or fish, or by layers of water differentiated by sudden changes of temperature or salinity (or both). False echoes are occasionally recorded by echo sounders, and might be interpreted erroneously as the correct depth. Also called side echo(es) or false target. See phantom bottom. [14] |
| 3612 | Ekman Transport | Net surface water transport due to the ekman spiral. In the northern hemisphere the transport is 90° to the right of the surface wind direction. [1] |
| 3613 | Enamelled Plate | In cartography, enamelled working surface (normally white), on aluminium, zinc or other dimensionally stable medium. Used to prepare colour separation originals. [14] |
| 3614 | Energy: Radiant | Energy transmitted by radiation. [14] |
| 3615 | Entrance Window | The image of the field stop formed by all the lens elements on the object side of the field stop. [14] |
| 3616 | Equation Method | In tidal terminology, an elaborate non-harmonic method for the prediction of tides. [14] |
| 3617 | Equation: Error | The probability equation which expresses the laws of the occurrence of accidental errors. The error equation is the basis of the method of least squares, used in the adjustment of observations for determining the most probable value of a result from those observations. [14] |
| 3618 | Error: Absolute | Absolute deviation (the value taken without regard to sign) from the corresponding true value. [14] |
| 3619 | Error: Clamping | A systematic error in observations made with a repeating theodolite caused by strains set up by the clamping devices of the instrument. [14] |
| 3620 | Error: Constant | A systematic error which is the same in both magnitude and sign through a given series of observations. [14] |
| 3621 | Error: External | See error: theoretical. [14] |
| 3622 | Error: Periodic | An error whose amplitude and direction vary systematically with time. [14] |
| 3623 | Error: Personal | The result of the inability of an observer to perceive dimensional values exactly. Personal errors may be either random or systematic in behavior. See also personal equation. [14] |
| 3624 | Error: Probable | An error (or deviation from the mean) of such magnitude that the likelihood of its being exceeded in a set of observations is equal to the likelihood of its not being exceeded; its value is that of the standard error multiplied by 0.6745. The use of standard error is sometimes preferred in statistical studies. [14] |
| 3625 | Error: Residual | The difference between any value of a quantity in a series of observations, corrected for known systematic errors, and the value of the quantity obtained from the adjustment of that series. Sometimes termed as residual. [14] |
| 3626 | Facility (Port) | See harbor works. [14] |
| 3627 | Fixing Interval | The time or distance elapsed between two subsequent fixes. [14] |
| 3628 | Foot (Pl. Feet) | A unit of length equal to 12 inches, 1/6 of a fathom, or 30.480 centimeters. [14] |
| 3629 | Free Atmosphere | See atmosphere. [14] |
| 3630 | Free Convection | See convection. [14] |
| 3631 | Frontal Surface | See front. [14] |
| 3632 | Gate: Hydraulic | A form of valve used to regulate the flow of a liquid in a pipeline, river or dam. [14] |
| 3633 | Gauge: Pressure | An instrument for measuring pressure. A tide gauge operated by the change in pressure at the bottom of a body of water, due to the rise and fall of the tide. [14] |
| 3634 | General Notices | All information and instructions that hydrographic offices may wish to bring to the attention of mariners but the nature of which is such that they may not properly refer to any specific nautical document. [14] |
| 3635 | Grad (Or Grade) | A unit of angle measurement, equal to the angle at the center of a circle, subtended by one four-hundredth part of its circumference. [14] |
| 3636 | Grid Navigation | See navigation. [14] |
| 3637 | Ground Distance | The great-circle distance between two ground positions, as contrasted with slant distance. Also called ground range. [14] |
| 3638 | Ground Parallel | See parallel. [14] |
| 3639 | Gyroscope: Free | See gyro: free. [14] |
| 3640 | Hanging Compass | See compass. [14] |
| 3641 | Harbour: Island | A harbor formed, or mainly protected, by islands. [14] |
| 3642 | Heat Index (Hi) | An index that combines air temperature and relative humidity to determine an apparent temperature how hot it actually feels. [1] |
| 3643 | High Water Mark | The mark left by the tide at high water. The line or level reached, especially the highest line ever reached. Also called high water line. A permanent mark which indicates the maximum observed stage of tide. [14] |
| 3644 | Hydrophotometer | An instrument used to measure the extinction coefficient of transmission of light in water. It consists of a constant light source placed at a specific distance from a photocell. When placed in water, the electrical output of the photocell is proportional to the amount of light striking the cell which, in turn, depends upon the transparency of the water. The instrument is calibrated to read 100 percent light transmission in air. [14] |
| 3645 | Image: Inverted | An image that appears upside down in relation to the object. [14] |
| 3646 | Inner Neat Line | See neat line. [14] |
| 3647 | Input Impedance | The complex opposition to alternating current between the input terminals of any device. [14] |
| 3648 | Intertidal Zone | The zone generally considered to be between mean high water and mean low water levels. [14] |
| 3649 | Isodynamic Line | A line connecting points of equal magnetic intensity, either the total or any component. [14] |
| 3650 | Land Navigation | See navigation. [14] |
| 3651 | Latitude Factor | The change in latitude along a celestial line of position per 1' change in longitude. [14] |
| 3652 | Level: Circular | See level: spirit. [14] |
| 3653 | Level: Striding | A spirit level so mounted that it can be placed above and parallel with the horizontal axis of a surveying or astronomical instrument, and so supported that it can be used to measure the inclination of the horizontal axis to the plane of the horizon. Generally, its mounting has supports in the form of inverted eyes which rest directly upon the pivots on which the telescope of the instrument rotates. [14] |
| 3654 | Levelling Plate | A plate designed to support the levelling rod as an aid to accuracy in levelling. [14] |
| 3655 | Levelling Screw | One of the three screws of surveying and astronomic instruments used for levelling same. Also called footscrew. [14] |
| 3656 | Levelling Staff | See levelling rod. [14] |
| 3657 | Light(S): Range | Two or more lights in the same horizontal direction, particularly those lights so placed as navigational aids to mark any line of importance to vessels, as a channel. The one nearest the observer is the front light and the one farthest from the observer is the rear light. See light(s): leading. [14] |
| 3658 | Light(S): Tidal | Lights shown at the entrance of a harbor to indicate tide and tidal current conditions within the harbor. [14] |
| 3659 | Light: Dioptric | A light concentrated into a parallel beam by means of refracting lenses and prisms (as opposed to catoptric). [14] |
| 3660 | Light: Flashing | A rhythmic light in which the total duration of light in a period is clearly shorter than the total duration of darkness and all the appearances of light are of equal duration. [14] |
| 3661 | Light: Isophase | See light: equal-interval. [14] |
| 3662 | Line Of Apsides | The line connecting the two orbital points (called apsides) that are nearest and farthest from the center of attraction, as the perigee and the apogee in the case of an orbit about the earth, and the perihelion and the aphelion in the case of an orbit about the sun. [14] |
| 3663 | Log: Dutchman'S | A buoyant object thrown overboard to determine the speed of a vessel by timing its passage between two marks, of known distance apart, on the vessel. [14] |
| 3664 | Lookout Station | A distinctive structure or place on shore from which personnel keep watch upon events at sea or along the coast. [14] |
| 3665 | Low Water Stand | See stand of tide. [14] |
| 3666 | Magnetic Course | See course. [14] |
| 3667 | Magnetic Moment | The quantity obtained by multiplying the distance between two magnetic poles by the average strength of the poles. [14] |
| 3668 | Magnetic Survey | See survey. [14] |
| 3669 | Mammatus Clouds | Clouds that look like pouches hanging from the underside of a cloud. [1] |
| 3670 | Map: Anaglyphic | A map specially printed in two complementary colors in such a way that, when viewed through a twin eyepiece of the same colors, a three-dimensional impression of relief is seen. [14] |
| 3671 | Map: Manuscript | The original drawing of a map as compiled or constructed from various data, such as ground surveys, photographs, etc. [14] |
| 3672 | Map: Substitute | A hasty reproduction of wide-coverage aerial photographs, photomaps, or mosaics, or of provisional maps, or any document used in place of a map, when the precise requirements of a map cannot be met. [14] |
| 3673 | Marks And Deeps | The divisions used in marking a hand lead line. [14] |
| 3674 | Maunder Minimum | A period from about 1645 to 1715 when few, if any, sunspots were observed. [1] |
| 3675 | Mean Neap Range | See neap range. [14] |
| 3676 | Mean Tide Level | See half tide level. [14] |
| 3677 | Meridian: Local | The meridian through any particular place or observer, serving as the reference for local time, in contrast with Greenwich meridian. [14] |
| 3678 | Meridian: Prime | The meridian of longitude 0°, used as the origin for measurement of longitude. The meridian of Greenwich, England, is almost universally used for this purpose. [14] |
| 3679 | Meridional Flow | A type of atmospheric circulation pattern in which the north-south component of the wind is pronounced. [1] |
| 3680 | Micrometer Drum | A graduated drum by which the motion of a traveling wire in a microscope can be measured. [14] |
| 3681 | Minimum Squares | See least squares. [14] |
| 3682 | Month: Sidereal | The interval of time between two successive passages of the moon past as fixed star. The length of the sidereal month averages 27.321661 mean solar days. [14] |
| 3683 | Month: Tropical | The average period of revolution of the moon about the earth with respect to the vernal equinox. The length of the tropical month averages 27.321582 mean solar days. [14] |
| 3684 | Nacreous Clouds | Clouds of unknown composition that have a soft, pearly luster and that form at altitudes about 25 to 30 km above the earth's surface. They are also called mother-of-pearl clouds. [1] |
| 3685 | North: Magnetic | The direction indicated by the north seeking pole of a freely suspended magnetic needle influenced only by the earth's magnetic field. [14] |
| 3686 | Oceanic Plateau | A comparatively flat topped elevation of the sea-bed which rises steeply from the ocean floor on all sides, and is of considerable extent across the summit. [14] |
| 3687 | Operative Sheet | See field board. [14] |
| 3688 | Opposite Coasts | The geographical relationship of the coasts of two states facing each other. [14] |
| 3689 | Orchard Heaters | Oil heaters placed in orchards that generate heat and promote convective circulations to protect fruit trees from damaging low temperatures. Also called smudge pots. [1] |
| 3690 | Orthophotoscope | A photomechanical device, used in conjunction with a double-projection anaglyphic instrument, for producing orthophotographs. [14] |
| 3691 | Outgoing Stream | See ebb stream. [14] |
| 3692 | Overlay Tracing | A plotting on tracing cloth at the scale of the smooth sheet used in conjunction with the smooth sheet. See fair chart. [14] |
| 3693 | Parallax: Solar | The equatorial horizontal parallax of the sun. [14] |
| 3694 | Partial Eclipse | See eclipse. [14] |
| 3695 | Phosphorescence | The production of light without sensible heat. Emission of electromagnetic radiation by a substance as a result of previous absorption of radiation of shorter wavelength. In contrast to fluorescence, the emission may continue for a considerable time after cessation of the existing irradiation. [14] |
| 3696 | Photogoniometer | An instrument for measuring angles from the true perspective center to points on a photograph. [14] |
| 3697 | Photograph Axes | See fiducial axes. [14] |
| 3698 | Photolithograph | A lithograph produced by photolithography. See lithography. [14] |
| 3699 | Phototopography | The science of surveying in which the detail is plotted entirely from photographs taken at suitable ground stations. [14] |
| 3700 | Pilotage Waters | See pilot waters. [14] |
| 3701 | Plane: Vertical | Any plane passing through a point on the earth and containing the zenith and nadir of that point. In surveying, a plane at right angles to a horizontal plane and within which angles and distances are observed. [14] |
| 3702 | Planimetric Map | See map. [14] |
| 3703 | Platform Jacket | The section of a platform from base to deck level, on which deck modules are fitted. [14] |
| 3704 | Platform: Piled | A platform with a steel jacket fixed by piles to the seabed. [14] |
| 3705 | Pole: Depressed | The celestial pole below the horizon, of opposite name to the latitude. [14] |
| 3706 | Position Angles | The two sextant angles observed on a survey ship for determining its position. [14] |
| 3707 | Position: Field | A position computed while field work is in progress to determine the acceptability of the observa-tions or to provide a preliminary position for other purposes. [14] |
| 3708 | Preferred Datum | A geodetic datum selected as a base for consolidation of local independent datums within a geographical area. Also called major datum. [14] |
| 3709 | Pressure: Sound | The instantaneous pressure at a point in a medium in the presence of a sound wave, minus the static pressure at that point. [14] |
| 3710 | Prevailing Wind | The wind direction most frequently observed during a given period. [1] |
| 3711 | Principal Scale | See scale. [14] |
| 3712 | Printing Plates | Any one-piece printing surface of any size, strength, or surface preparation, bearing an image made manually, mechanically or photographically, specifically for the purpose of printing such an image onto some other material. [14] |
| 3713 | Prohibited Area | An area shown on charts within which navigation and/or anchoring is prohibited. In aviation terminology, a specified area within the land areas of a state or territorial waters adjacent thereto over which the flight of aircraft is prohibited. [14] |
| 3714 | Quality Control | All procedures which ensure that the product meets certain standards and specifications. [14] |
| 3715 | Quarantine Buoy | A buoy marking the location of a quarantine anchorage. [14] |
| 3716 | Radar Reflector | A device capable of or intended for reflecting radar signals. [14] |
| 3717 | Radar-Responder | See radar beacon. [14] |
| 3718 | Radio Frequency | See frequency. [14] |
| 3719 | Radiotheodolite | Electronic theodolite designed to give the direction in space of a radio transmitter carried by a free balloon. [14] |
| 3720 | Range: Cruising | see cruising radius. [14] |
| 3721 | Range: Magnetic | A range oriented in a given magnetic direction and used to assist in determination of the deviation of a magnetic compass. See deviation: magnetic. [14] |
| 3722 | Ratio Of Ranges | The ratio of the height of tide at the subordinate station to the height of tide at the reference station. [14] |
| 3723 | Resolving Power | A mathematical expression of definition in a radar or optical system, usually stated as the maximum number of lines per millimeter that can be seen as separate lines in the image. [14] |
| 3724 | Reverse Azimuth | See azimuth: back. [14] |
| 3725 | Revolving Light | See light: rotating. [14] |
| 3726 | Rho-Teta System | Positioning system measuring the distance (rho) and direction (teta) from an existing control station to a mobile or another point. [14] |
| 3727 | River Discharge | The rate of flow of water past a point in a stream, expressed as volume per unit time (usually cubic feet per second). [14] |
| 3728 | River Roadstead | A roadstead which lies in a river. [14] |
| 3729 | Roaring Forties | An expression often used to denote that belt in the oceans, between 40° and 50° south latitude, where strong westerly winds prevail. [14] |
| 3730 | Rocket Sounding | Determination of one or more upper-air meteorological elements by means of rocket-borne instruments. [14] |
| 3731 | Runway Light(S) | See light. [14] |
| 3732 | Safe Water Mark | in the IALA maritime buoyage system a navigation mark used to indicate that there is navigable water around its position with no known hazards nearby. [14] |
| 3733 | Scale: Latitude | The subdivided east and west borders of a Mercator chart into degrees and minutes. A variant of the bar scale, since a minute of latitude is very nearly equal to a nautical mile. [14] |
| 3734 | Secondary Radar | See radar: primary. [14] |
| 3735 | Sediment Survey | A survey to determine the nature and distribution of types of sea bottom sediments. [14] |
| 3736 | Separation Line | See separation zone. [14] |
| 3737 | Sextant: Bubble | A sextant with a bubble or spirit level to indicate the horizontal. [14] |
| 3738 | Sextant: Marine | A sextant designed primarily for marine navigation. [14] |
| 3739 | Shoaling Effect | The alteration of a wave proceeding from deep water to shallow water. [14] |
| 3740 | Shutter: Louver | A shutter consisting of a number of thin metal strips or louvers which operate like a venetian blind to make the exposure; usually located just in front of or just behind the lens. [14] |
| 3741 | Signal: Weather | A visual signal displayed to indicate a weather forecast. [14] |
| 3742 | Single Day Tide | See tide: diurnal. [14] |
| 3743 | Solar Radiation | Radiation emitted by the sun. [14] |
| 3744 | Sonic Frequency | See audio frequency. [14] |
| 3745 | Sono-Radio Buoy | See sonobuoy. [14] |
| 3746 | Sound Intensity | See intensity. [14] |
| 3747 | Sounding Bottle | A strong metal container fitted with non-return valves for taking water samples at great depths. See also water bottle. [14] |
| 3748 | Sounding Record | Bound record book in which all of the data taken on a hydrographic survey are entered, and become part of the permanent records of the survey. Also called sounding book. [14] |
| 3749 | Sounding: Drift | A method of finding the least depth in a shoal area by letting the boat drift along a series of closely spaced, previously run parallel sounding lines, while the leadsman sounds or 'feels' along the bottom. The operation is repeated until the shoal is found or the area is covered. [14] |
| 3750 | Speed Made Good | The actual velocity of the ship along a course measured in relation to the ocean bottom or to fixed objects ashore. [14] |
| 3751 | Speed: Relative | See relative motion. [14] |
| 3752 | St. Elmo'S Fire | A bright electric discharge that is projected from objects (usually pointed) when they are in a strong electric field, such as during a thunderstorm. [1] |
| 3753 | Stadia Constant | The constant which is multiplied by the stadia interval to obtain the length of a sight in meters. [14] |
| 3754 | Stadia Interval | The length of rod subtended between the top and the bottom cross wires in the levelling instrument as seen projected against the face of the levelling rod. [14] |
| 3755 | Standardization | The comparison of an instrument or device with a standard to determine the value of the instrument or device in terms of an adopted unit. See calibration. [14] |
| 3756 | Star Identifier | See star finder. [14] |
| 3757 | Station: 'Lost' | See station: unrecoverable. [14] |
| 3758 | Station: Survey | See station. [14] |
| 3759 | Stationary Wave | See wave: standing. [14] |
| 3760 | Stream: Ingoing | See flood stream. [14] |
| 3761 | Streamline Flow | See laminar flow. [14] |
| 3762 | Submarine Cable | An assembly of wires or fibres, or a wire rope or chain, which has been laid underwater or buried beneath the sea floor. [14] |
| 3763 | Submarine Ridge | An elongated elevation of the sea floor, with either irregular or relatively smooth topography and steep sides which constitutes a natural prolongation of land territory. [14] |
| 3764 | Subtense Method | A procedure by which distance measurements are obtained by use of a subtense bar. [14] |
| 3765 | Summer Solstice | Approximately June 21 in the northern hemisphere when the sun is highest in the sky and directly overhead at latitude 231d2°n, the tropic of cancer. [1] |
| 3766 | Summer Solstice | See solstice. [14] |
| 3767 | Supersaturation | A condition whereby the atmosphere contains more water vapor than is needed to produce saturation with respect to a flat surface of pure water or ice, and the relative humidity is greater than 100 percent. [1] |
| 3768 | Surface Current | See current. [14] |
| 3769 | Surface Current | The current at the sea surface, which is partly due to the effects of wind and waves. Empirically, it is found that the drift current at the surface is 2.5%–3.0% of the wind speed, and it decreases rapidly in the uppermost meter. [5] |
| 3770 | Surge: Negative | An occasion when the level of the sea is lower than the predicted level. It is caused by meteorological conditions. [14] |
| 3771 | Surge: Positive | An occasion when the level of the sea is higher than the predicted level. It is caused by meteorological conditions. [14] |
| 3772 | Surging Breaker | See breaker. [14] |
| 3773 | Survey Traverse | See traverse. [14] |
| 3774 | Survey: Coastal | Hydrographic survey of coastal area including coast lining. [14] |
| 3775 | Survey: Harbour | Hydrographic survey of a harbor area. [14] |
| 3776 | Survey: Running | A hydrographic survey in which the greater part of the work is done from the ship steaming along the coast. A line of sounding is run on the course made good and any additional information of a hydrographic nature which can be obtained whilst under way, is collected. [14] |
| 3777 | Survey: Tagline | A large scale survey made by employing a tagline. An accurate method sometimes adopted in river and harbor work. [14] |
| 3778 | Swath(E) System | Any of a number of systems which are capable of obtaining a strip or lane of elevations or soundings from a single survey platforms ™s track. In hydrography, systems that fall into this category are multi beam echo sounders (mbes), interferometric echo sounders and lidar. [14] |
| 3779 | Tape: Reference | See reference tape. [14] |
| 3780 | Teleconnections | A linkage between weather changes occurring in widely separated regions of the world. [1] |
| 3781 | Theodolite Axes | See axis: horizontal and axis: vertical. [14] |
| 3782 | Theodolite Drag | See drag (of theodolite). [14] |
| 3783 | Thermal Equator | See equator. [14] |
| 3784 | Threshold Speed | The minimum speed of current at which a particular current meter will measure at its rated reliabi-lity. [14] |
| 3785 | Tidal Amplitude | The average difference between water levels at high and low tide ; One-half of the difference in height between consecutive high water and low water; hence, half of the tidal range. [6][8] |
| 3786 | Tide(S): Spring | The tides of increased range occurring near the times of full moon and new moon. [14] |
| 3787 | Tide: Vanishing | The phenomenon occurring when a high and low water 'melt' together into a period of several hours with a nearly constant water level. The tide is in the diurnal category but is known as a 'vanishing tide'. [14] |
| 3788 | Time: Universal | See universal time (ut). [14] |
| 3789 | Tornado Warning | A warning issued when a tornado has actually been observed either visually or on a radar screen. It is also issued when the formation of tornadoes is imminent. [1] |
| 3790 | Torsion Balance | A device for measuring very small forces of attraction resulting from gravitation, magnetism, etc., and consisting of a bar suspended horizontally by an elastic filament, one end of the bar being subjected to the influence of the attracting force to a greater degree than the other end. The attracting force is balanced and its comparative strength measured by the torsional reaction of the filament. [14] |
| 3791 | Track: Intended | The anticipated path of a vessel relative to the earth. [14] |
| 3792 | Transit Bearing | See bearing. [14] |
| 3793 | Tripping Device | A device to pull equipment out of or to lower it into water. [14] |
| 3794 | Tubular Compass | See compass. [14] |
| 3795 | Ultrashort Wave | See wave. [14] |
| 3796 | Universal Level | See level: spirit. [14] |
| 3797 | Unsurveyed Area | An area where hydrographic survey data is non-existent. [14] |
| 3798 | Vanishing Point | In photogrammetry, the image in the plane of a photograph, of the point toward which a system of parallel lines in the object space converges. [14] |
| 3799 | Visible Horizon | See horizon: apparent. [14] |
| 3800 | Water Levelling | See levelling. [14] |
| 3801 | Wave Generation | The creation of waves by natural or mechanical means. In wave forecasting the growth of waves caused by a wind blowing over a water surface for a certain period of time. The area involved is called the generating area or fetch. [14] |
| 3802 | Wave(S): Damped | Wave(s) the amplitude of which becomes progressively smaller. [14] |
| 3803 | Wave: Capillary | A wave whose velocity of propagation is controlled primarily by the surface tension of the liquid in which the wave is travelling. Water waves of length less than one inch are considered to be capillary waves. [14] |
| 3804 | Wave: Cycloidal | A very steep, symmetrical wave whose crest forms an angle of 120 degrees. The wave form is that of a cycloid. A trochoidal wave of maximum steepness. [14] |
| 3805 | Wave: Reflected | A wave that has had its direction of motion changed by reflection. [14] |
| 3806 | Wave: Refracted | A wave that has had its direction of motion changed by refraction. [14] |
| 3807 | Wave: Spherical | A wave whose wave front surfaces are concentric spheres. Such waves propagate from a point source. [14] |
| 3808 | Weather Warning | A forecast indicating that hazardous weather is either imminent or actually occurring within the specified forecast area. [1] |
| 3809 | Well: Appraisal | A borehole drilled to evaluate an oil field or gas field. [14] |
| 3810 | Well: Suspended | A borehole that has been temporarily abandoned pending future development. An obstruction up to 5 meters high may remain on the sea-floor. [14] |
| 3811 | Yaw (Or Yawing) | The ship's oscillation about a vertical axis approximately through the center of gravity of the vessel. [14] |
| 3812 | Zonal Wind Flow | A wind that has a predominate west-to-east component. [1] |
| 3813 | Zone Of Silence | See blind zone. [14] |
| 3814 | Zone: Equiphase | That region in space within which the difference in phase of two radio signals is indistinguishable. [14] |
| 3815 | Accidental Error | See error. [14] |
| 3816 | Acoustic Bearing | See bearing: sonic. [14] |
| 3817 | Active Satellite | An artificial satellite which transmits an electromagnetic signal. A satellite with the capability to transmit, repeat, or retransmit electromagnetic information as contrasted with passive satellite. 2. As defined by the international telecommunication union (itu), an earth satellite carrying a station intended to transmit or retransmit radiocommunication signals. [14] |
| 3818 | Aeromarine Light | See light. [14] |
| 3819 | Altimeter: Radar | See altimeter: radio. [14] |
| 3820 | Altitude: Flight | The vertical distance above a given datum, usually mean sea level, or an aircraft in flight. [14] |
| 3821 | Angle: Concluded | In a triangulation, the third angle of a triangle, not measured, but computed from the other two angles. [14] |
| 3822 | Angle: Vectorial | See coordinates: plane polar and coordinates: polar. [14] |
| 3823 | Anomalistic Year | See year. [14] |
| 3824 | Anomaly: Gravity | See gravity anomaly, bouguer anomaly, free air anomaly, isostatic anomaly. [14] |
| 3825 | Antarctic Circle | The geographic parallel having a south latitude equal to the complement of the declination of the winter solstice (latitude = 66 deg 33' s approximately). [14] |
| 3826 | Atmosphere: Free | That part of the atmosphere above the friction layer, in which the air motion is affected to a negligible degree by surface friction. [14] |
| 3827 | Atmosphere: Icao | Standard atmosphere adopted by the international civil aviation organization (ICAO). Its main features are mean sea-level pressure of 1013.25 mb, and a temperature lapse rate of 6.5° c/km from surface to the tropopause situated at 11 km. [14] |
| 3828 | Atmospheric Drag | A major perturbation of close artificial satellite orbits by the resistance of the atmosphere. [14] |
| 3829 | Aurora Australis | Aurora of the southern hemisphere. [14] |
| 3830 | Autumnal Equinox | The equinox at which the sun approaches the southern hemisphere and passes directly over the equator. Occurs around September 23. [1] |
| 3831 | Axis: Horizontal | In a theodolite or transit, the axis about which the telescope of the instrument rotates when moved vertically. Also called trunnion axis, or transit axis. [14] |
| 3832 | Azimuth: Forward | See azimuth: geodetic. [14] |
| 3833 | Azimuth: Laplace | A geodetic azimuth derived from an astronomic azimuth by means of the Laplace equation. [14] |
| 3834 | Azimuth: Reverse | See azimuth: back. [14] |
| 3835 | Backrush Current | See current: backrush. [14] |
| 3836 | Ballistic Camera | See camera. [14] |
| 3837 | Baseline: Normal | The low-water line along the coast as marked on large-scale charts officially recognized by the coastal state. [14] |
| 3838 | Bathythermograph | A device for obtaining a record of temperature against depth in the ocean, from a ship underway. [14] |
| 3839 | Bay Closing Line | A line dividing the internal waters and territorial seas in a bay. [14] |
| 3840 | Bearing: Compass | See bearing. [14] |
| 3841 | Bearing: Transit | A bearing taken of two objects when in line. [14] |
| 3842 | Bifurcation Buoy | See buoy: bifurcation. [14] |
| 3843 | Block Correction | See chartlet. [14] |
| 3844 | Bottom Sediments | See sediments: bottom. [14] |
| 3845 | Bridge Clearance | See clearance. [14] |
| 3846 | Broad On The Bow | Bearing 045° relative (broad on the starboard bow) or 315° relative (broad on the port bow). If the bearings are approximate, the expression on the bow should be used. See also on the bow. [14] |
| 3847 | Bull'S Eye Level | See level: spirit. [14] |
| 3848 | Cable: Submarine | An insulated, waterproof wire or bundle of wires for carrying an electric current under water. [14] |
| 3849 | Cadastral Survey | See survey. [14] |
| 3850 | Calling-In Point | a designated position at which vessels are required to report to a traffic control center. Also called reporting point or radio reporting point. [14] |
| 3851 | Camera: Deep Sea | A camera system specially designed for obtaining photographs of the ocean bottom. [14] |
| 3852 | Camera: Tracking | See camera: ballistic. [14] |
| 3853 | Cathode-Ray Tube | A vacuum tube in which electrons emitted by a hot cathode are formed into a narrow beam, accelerated at high velocity and directed towards a specially prepared screen which fluoresces at the point where the electrons strike. [14] |
| 3854 | Chain Adjustment | A mathematical adjustment of a whole series of figures, for example, a chain of triangulation. [14] |
| 3855 | Chart Production | All processes in the design, compilation, draughting and reproduction of a chart. [14] |
| 3856 | Chart Projection | See projection. [14] |
| 3857 | Chronometer Rate | The amount gained or lost by a chronometer in a unit of time. It is usually expressed in seconds per 24 hours, and is sometimes called daily rate. [14] |
| 3858 | Circle: Vertical | A great circle on the celestial sphere passing through the zenith and nadir. Vertical circles are perpendicular to the horizon. In a surveying instrument, the graduated circle used for measuring vertical angles. [14] |
| 3859 | Collimator: Auto | A collimator provided with a means of illuminating its cross hairs so that, when a reflecting plane is placed normal to the emergent light beam, the reflected image of the cross hairs appears to be coincident with the cross hairs themselves. This device is used in calibrating optical and mechanical instruments. [14] |
| 3860 | Comb: Micrometer | See micrometer. [14] |
| 3861 | Compact Pack Ice | Pack ice in which the concentration is 10/10 (8/8) and no water is visible. [14] |
| 3862 | Compass: Dipping | See dip circle. [14] |
| 3863 | Compass: Tubular | A compass supplied for attachment to certain types of levels and theodolites. [14] |
| 3864 | Contour Interval | The difference in elevation between adjacent contours. [14] |
| 3865 | Contour Sweeping | A form of bar sweeping. A sweep, set at a predetermined depth, and passed over the bottom at right angles to the depth contours. When contact is made the position is recorded. [14] |
| 3866 | Convection: Free | In the atmosphere, convection caused by density differences within the air. [14] |
| 3867 | Convergence Zone | In oceanography, region of convergence. The region in the deep ocean where sound rays, refracted from the depths, arrive at the surface in successive intervals of 30 to 35 nautical miles. [14] |
| 3868 | Corer: Polyvinyl | See corer: hydroplastic. [14] |
| 3869 | Cosmic Radiation | Radiation, of very high energy and great penetrative power, which emanates from cosmic regions. [14] |
| 3870 | Course: Magnetic | See course. [14] |
| 3871 | Crepuscular Rays | Alternating light and dark bands of light that appear to fan out from the sun's position, usually at twilight. [1] |
| 3872 | Current: Coastal | A relatively uniform drift usually flowing parallel to the shore in the deeper water adjacent to the surf zone. [14] |
| 3873 | Current: Density | A gradient current caused by the horizontal gradient of water density. [14] |
| 3874 | Current: Diurnal | The type of tidal current having only one flood and one ebb period in a tidal day. [14] |
| 3875 | Current: Surface | A current that does not extend more than a few (2-3) meters below the surface. [14] |
| 3876 | Cycle Per Second | A unit of frequency more and more superseded by the hertz. [14] |
| 3877 | Cylindrical Buoy | See can buoy. [14] |
| 3878 | Datum: Levelling | See datum: vertical control. [14] |
| 3879 | Day: Constituent | The duration of one rotation of the earth on its axis, with respect to a fictitious star representing one of the periodic elements in the tidal forces. It approximates the length of a lunar or solar day. The expression is not applicable to a long-period constituent. [14] |
| 3880 | Deadbeat Compass | See compass. [14] |
| 3881 | Deep Water Route | A route in a designated area within defined limits which has been accurately surveyed for clearance of sea bottom and submerged obstacles to a minimum indicated depth of water. [14] |
| 3882 | Degaussing Cable | See cable. [14] |
| 3883 | Dendrochronology | The analysis of the annual growth rings of trees as a means of interpreting past climatic conditions. [1] |
| 3884 | Direct Levelling | See levelling. [14] |
| 3885 | Distortion: Lens | See distortion. [14] |
| 3886 | Double Low Water | See low water. [14] |
| 3887 | Drafted Original | A scribed or drafted chart or portion of a chart on stable base material, which may be processed for final reproduction. [14] |
| 3888 | Drifting Logship | A logship employed for the measurement of tidal streams and currents. It is allowed to drift freely while its positions are fixed, during the period of observation, by an accompanying boat, or from stations ashore. [14] |
| 3889 | Duration Of Tide | The time interval between low water and the following high water or between high water and the following low water. [14] |
| 3890 | Eagre (Or Eager) | See bore. [14] |
| 3891 | Eclipse: Annular | An eclipse in which a thin ring of the source of light appears around the obscuring body. Annular solar eclipses occur, but never annular lunar eclipses. [14] |
| 3892 | Eclipse: Partial | An eclipse in which only part of the source of light is obscured. [14] |
| 3893 | Electrostriction | Term applied to the creation of elastic tension and changes of shape and volume of an uncharged isolator by an electrical field. [14] |
| 3894 | Equation Of Time | The correction to be applied to 12 hours plus universal time to obtain the Greenwich hour angle of the sun, or more generally the correction to be applied to 12 hours plus local mean time to obtain the local hour angle of the sun. [14] |
| 3895 | Equation: Normal | One of a set of simultaneous equations derived from observation, condition or correlate equations. In a least-squares adjustment, values obtained from the solution of normal equations (either directly or through the correlate equations) are applied to the observation or condition equations to obtain the desired corrections. [14] |
| 3896 | Equator: Thermal | Line which circumscribes the earth and connects all points of highest mean annual temperature on each meridian. Also called heat equator. [14] |
| 3897 | Equatorial Calms | Zone of calm or light variable winds encountered, in certain regions, between the trade winds of the two hemispheres. [14] |
| 3898 | Equinoctial Year | See year: tropical. [14] |
| 3899 | Equivalent Scale | See scale. [14] |
| 3900 | Error: Irregular | See error: accidental. [14] |
| 3901 | Everest Spheroid | See reference spheroid. [14] |
| 3902 | Expansion Factor | In radiolocation, factor representing the degree to which the hyperbolae belonging to a given group of hyperbolic lines of position move apart as the distance from the base line increases. [14] |
| 3903 | Eye Of The Storm | See tropical cyclone. [14] |
| 3904 | Fahrenheit Scale | A temperature scale where 32 is assigned to the temperature where water freezes and 212 to the temperature at which water boils (at sea level). [1] |
| 3905 | Field Inspection | In photogrammetry, the process of comparing aerial photographs with conditions as they exist on the ground, and of obtaining information to supplement or clarify that not readily discernible on the photographs themselves. [14] |
| 3906 | Fiord (Or Fjord) | A long narrow arm of the sea, running up between high banks or cliffs, as on the coast of norway. Often has a relatively shallow sill across its entrance. [14] |
| 3907 | Fix: Three-Point | A fix obtained by simultaneously observing, with sextants, the two adjacent angles between three suitably disposed objects whose positions are known, and plotting the position by a station pointer. See also resection and three-point problem. [14] |
| 3908 | Flat-Bed Plotter | A plotter which uses a flat surface to mount the drawing base. [14] |
| 3909 | Fractional Scale | See scale: natural. [14] |
| 3910 | Free-Air Anomaly | The difference between observed gravity and theoretical gravity which has been computed for latitude and corrected for elevation of the station above or below the geoid, by application of the normal rate of change of gravity for change of elevation, as in free air. Also called faye anomaly. [14] |
| 3911 | Geostrophic Wind | That horizontal wind velocity for which the coriolis force exactly balances the horizontal pressure force. [14] |
| 3912 | Grid Declination | The angular difference in direction between grid north and true north. It is measured east or west from true north. [14] |
| 3913 | Hanging Traverse | See traverse: open. [14] |
| 3914 | Helmert Spheroid | See reference spheroid. [14] |
| 3915 | High Water (H.W) | The highest level reached at a place by the water surface in one oscillation. Also called high tide. [14] |
| 3916 | High Water Stand | See stand of tide. [14] |
| 3917 | Highland Climate | The climate of high elevations. Also called mountain climate. There is no single climatic type but a variety of different climate zones often characterized by a rapid change in temperature and precipitation as one ascends or descends in elevation. [1] |
| 3918 | Hydrologic Cycle | A model that illustrates the movement and exchange of water among the earth, atmosphere, and oceans. [1] |
| 3919 | Hydrologic Front | A relatively narrow transition zone separating two water masses in the ocean. [14] |
| 3920 | Index Correction | That correction due to index error. [14] |
| 3921 | Innocent Passage | Navigation through certain sea areas of a coastal state without being prejudicial to the peace, good order or security of that state. See also transit passage. [14] |
| 3922 | Intensity: Sound | At a point, the average rate of sound energy transmitted in a specified direction through a unit area normal to this direction at the point considered. The square of the sound pressure. [14] |
| 3923 | Inverted Compass | See compass: hanging. [14] |
| 3924 | Ionospheric Wave | See wave: sky. [14] |
| 3925 | Isomagnetic Line | A line connecting points of equality in some magnetic element. [14] |
| 3926 | Laplace Equation | See equation. [14] |
| 3927 | Large Correction | (British terminology). A new printing of a chart corrected from important information which is too comprehensive to promulgate by admiralty notices to mariners or to insert conveniently by hand on existing copies of the chart. When large corrections are made, the chart is not revised throughout but all copies in circulation are cancelled. [14] |
| 3928 | Leading Light(S) | See light. [14] |
| 3929 | Lenticular Cloud | A cloud in the shape of a lens. [1] |
| 3930 | Level: Universal | See level: spirit. [14] |
| 3931 | Levelling: Water | A method of obtaining relative elevations by observing heights with respect to the surface of a body of still water, such as a lake. The relative elevations of objects along its shores are obtained by taking the differences of their heights with respect to the surface of the water. [14] |
| 3932 | Light(S): Runway | Lights marking a runway. [14] |
| 3933 | Light: Catoptric | A light concentrated into a narrow beam by means of one or more reflectors (as opposed to dioptric). [14] |
| 3934 | Light: Occulting | A rhythmic light in which the total duration of light in a period is clearly longer than the total duration of darkness and all the eclipses are of equal duration. [14] |
| 3935 | Light: Revolving | See light: rotating. [14] |
| 3936 | Light: Unwatched | A navigational light, usually automatic in operation, without any permanently stationed personnel to superintend it. [14] |
| 3937 | Litre (Or Liter) | The basic unit of capacity in the metric system. It is equal to one cubic decimetre. [14] |
| 3938 | Local Hour Angle | See hour angle. [14] |
| 3939 | Log Factor Scale | See scale. [14] |
| 3940 | Longitude Factor | The change in longitude along a celestial line of position per 1' change in latitude. [14] |
| 3941 | Longitude Signal | See signal. [14] |
| 3942 | Low Water (L.W.) | The lowest level reached at a place by the water surface in one oscillation. Also called low tide. [14] |
| 3943 | Lowest Low Water | An arbitrary level conforming to the lowest tide observed at a place, or somewhat lower. [14] |
| 3944 | Loxodromic Curve | A loxodrome. A rhumb line. [14] |
| 3945 | Lunar Inequality | Variation in the moon's motion in its orbit, due to attraction by other bodies of the solar system. See evection, perturbation. A minute fluctuation of a magnetic needle from its mean position, caused by the moon. [14] |
| 3946 | Magnetic Azimuth | See azimuth. [14] |
| 3947 | Magnetic Equator | See equator. [14] |
| 3948 | Magnetic Station | See station. [14] |
| 3949 | Magnifying Glass | A lens or combination of lenses that increases the apparent size of an object seen through it. [14] |
| 3950 | Magnifying Power | The ratio of the apparent length of a linear dimension as seen through an optical instrument to that seen by the unaided eye. Sometimes shortened to power. [14] |
| 3951 | Maintained Depth | The depth at which a channel is kept by human influence, usually by dredging. [14] |
| 3952 | Map: Planimetric | A map which presents only the horizontal positions for the features represented; distinguished from a topographic map by the omission of relief in measurable form. [14] |
| 3953 | Map: Topographic | A map which represents the horizontal and vertical positions of the features represented; distinguished from a planimetric map by the addition of relief in measurable form. A topographic map uses contours or comparable symbols to show mountains, valleys and plains. [14] |
| 3954 | Marine Barometer | See barometer. [14] |
| 3955 | Mean Spring Rise | The height of mean high water springs above the chart datum. Also called spring rise. [14] |
| 3956 | Mercator Sailing | See sailing. [14] |
| 3957 | Meridian Sailing | See sailing. [14] |
| 3958 | Meridional Plane | Any plane containing the polar axis of the earth. [14] |
| 3959 | Metre (Or Meter) | The basic unit of length in the si system. [14] |
| 3960 | Mid-Channel Buoy | A buoy for marking the middle of a channel. [14] |
| 3961 | Middle Latitudes | The region of the world typically described as being between 30° and 50° latitude. [1] |
| 3962 | Mid-Extreme Tide | See tide. [14] |
| 3963 | Mirage: Inferior | Particular case of mirage, occurring over stretches of water, land, shores, roads, etc. Strongly heated by insolation, and in which the virtual image is found below the actual object. The case in which objects situated on or slightly above the normal horizon become invisible is popularly termed sinking. [14] |
| 3964 | Mirage: Superior | Special case of mirage, observable over snow-fields, cold seas, etc., in which the virtual image is above the actual object. The case in which objects below and beyond the normal horizon become visible is popularly termed looming. [14] |
| 3965 | Month: Dracontic | See month: nodical. [14] |
| 3966 | Month: Synodical | The interval of time between two successive conjunctions or oppositions of the moon. The length of the synodical month is 29.5305888 mean solar days. Also called lunation or lunar month. [14] |
| 3967 | Morse Code Light | See light. [14] |
| 3968 | Navigable Waters | Waters usable, with or without improvements, as routes for commerce in the customary means of travel on water. [14] |
| 3969 | Navigation: Grid | Navigation by the use of grid directions. [14] |
| 3970 | Nontidal Current | See current. [14] |
| 3971 | Obstruction Buoy | A buoy marking an obstruction. [14] |
| 3972 | Occasional Light | See light. [14] |
| 3973 | Operating System | System which controls and monitors the execution of programs in the computer. [14] |
| 3974 | Orthophotomosaic | An assembly of orthophotographs forming a uniform-scale mosaic. [14] |
| 3975 | Outfall Diffuser | A structure on an outfall through which liquids are discharged. The structure will usually project above the level of the outfall and can be an obstruction to navigation. [14] |
| 3976 | Outflow Boundary | A surface boundary separating cooler more-dense air from warmer less-dense air. Outflow boundaries formed by the horizontal spreading of cool air that originated inside a thunderstorm. [1] |
| 3977 | Overlapping Pair | In photogrammetry, two photographs taken at different exposure stations in such a manner that a portion of one photograph shows the same terrain as shown on a portion of the other photograph. This term covers the general case and does not imply that the photographs were taken for stereoscopic examination. See also stereoscopic pair. [14] |
| 3978 | Overshooting Top | A situation in a mature thunderstorm where rising air, associated with strong convection, penetrates into a stable layer (usually the stratosphere), forcing the upper part of the cloud to rise above its relatively flat anvil top. [1] |
| 3979 | Parachute Drogue | See drogue. [14] |
| 3980 | Parallactic Grid | See grid. [14] |
| 3981 | Parallax: Linear | See parallax: absolute stereoscopic. [14] |
| 3982 | Parallel Sailing | See sailing. [14] |
| 3983 | Parallel: Ground | In photogrammetry, the intersection of the plane of the photograph with the plane of reference of the ground. See also axis of homology. [14] |
| 3984 | Particular Scale | See scale. [14] |
| 3985 | Peak Wave Period | Tp ; The wave period with the highest energy. ; Determined by the inverse of the frequency at which a wave energy spectrum reaches its maximum. ; Reciprocal of the frequency corresponding to the largest value (peak) of the frequency wave spectrum. The frequency wave spectrum is obtained by integrating the two-dimensional wave spectrum over all directions. [9][10][11] |
| 3986 | Pelagic Division | In the classification of the marine environment and its inhabitants, a primary division of the sea which includes the whole mass of water. The division is made up of the neritic province which includes that water shallower than 200 meters, and the oceanic province which includes that water deeper than 200 meters. The other primary division of the sea is the benthic division. [14] |
| 3987 | Pendulum Sextant | See sextant. [14] |
| 3988 | Periodic Current | See current. [14] |
| 3989 | Periodic Wave(S) | See wave. [14] |
| 3990 | Perspective Grid | See grid. [14] |
| 3991 | Phase Inequality | Variations in the tides or tidal currents associated with changes in the phase of the moon. [14] |
| 3992 | Phase Modulation | See modulation. [14] |
| 3993 | Photodelineation | The delineation of features on a photograph. See also compilation. [14] |
| 3994 | Photolithography | That branch of lithographic printing in which photography is employed for production of the image on the final printing surface. The original printing surface, lithographic stone, has been almost completely displaced by thin and flexible sheets of metal (zinc, aluminium, stainless steel, bimetallic plates, polymetallic plates). [14] |
| 3995 | Photozincography | The use of a zinc plate in photoengraving. [14] |
| 3996 | Piezoelectricity | The property exhibited by some asymmetrical crystalline materials which when subjected to strain in suitable directions develop electric polarization proportional to the strain. Inverse piezoelectricity is the effect in which mechanical strain is produced in certain asymmetrical crystalline materials when subjected to an external electric field; the strain is proportional to the electric field. [14] |
| 3997 | Planet(S): Major | The four largest planets (jupiter, saturn, uranus and neptune). [14] |
| 3998 | Planet(S): Minor | See asteroid. [14] |
| 3999 | Plunging Breaker | See breaker. [14] |
| 4000 | Point Of Arrival | See arrival: point of. [14] |
| 4001 | Polar Easterlies | A shallow body of easterly winds located at high latitudes poleward of the subpolar low. [1] |
| 4002 | Progressive Wave | See wave. [14] |
| 4003 | Prolate Spheroid | See spheroid. [14] |
| 4004 | Prominent Object | Objects which are easily identifiable, but do not justify being classed as conspicuous. [14] |
| 4005 | Propagated Error | An error which occurs in one operation and contaminates subsequent operations. [14] |
| 4006 | Protractor: Cust | Square or rectangular sheet of transparent xylonite engraved with a circle graduated in degrees and half degrees. Observed angles are drawn, in general, on the under side. See protractor: three arm. [14] |
| 4007 | Pulse Modulation | See modulation. [14] |
| 4008 | Radar: Secondary | See radar: primary. [14] |
| 4009 | Radio Fog Signal | See fog signal. [14] |
| 4010 | Radiobeacon Buoy | See buoy. [14] |
| 4011 | Radius: Cruising | See cruising radius. [14] |
| 4012 | Reduced Latitude | See latitude: parametric. [14] |
| 4013 | Reference Object | A well-defined object selected as a starting point in the direction method of observation. [14] |
| 4014 | Relative Bearing | See bearing. [14] |
| 4015 | Scale: Numerical | See scale: natural. [14] |
| 4016 | Scale: Principal | The scale of a reduced or generating globe representing the sphere or spheroid defined by the fractional relation of their respective radii. [14] |
| 4017 | Scales Of Motion | The hierarchy of atmospheric circulations from tiny gusts to giant storms. [1] |
| 4018 | Seasonal Current | See current. [14] |
| 4019 | Seismic Sea Wave | See tsunami. [14] |
| 4020 | Sensible Horizon | See horizon. [14] |
| 4021 | Sensitive Bubble | See level: spirit. [14] |
| 4022 | Sequence Of Tide | The order in which the tides of a day occur, with special reference to whether the higher high water immediately precedes or follows the lower low water. [14] |
| 4023 | Signal: Luminous | In surveying, a signal consisting of heliotrope or heliostat by day, and selenotrope or signal lamp by night. [14] |
| 4024 | Skew Convergence | The angle, on a skewed projection, between true north and skew north. [14] |
| 4025 | Solsticial Point | See solstice. [14] |
| 4026 | Sonic Navigation | See navigation. [14] |
| 4027 | Sounding Machine | An instrument for measuring depth of water, consisting essentially of a reel of wire to one end of which is attached a weight which carries a device for recording the depth. A crank or motor is provided for reeling in the wire. [14] |
| 4028 | Sounding: Danger | A minimum sounding chosen for a vessel of specific draft in a given area to indicate the limit of safe navigation. [14] |
| 4029 | Space Modulation | See modulation. [14] |
| 4030 | Specific Gravity | The ratio of the density of a substance at a given temperature and the density of some other substance used as a standard. For liquids and solids, the standard assumed is the density of distilled water at 4°c. [14] |
| 4031 | Spilling Breaker | See breaker. [14] |
| 4032 | State Of The Sea | See sea state. [14] |
| 4033 | Station Pressure | The actual air pressure computed at the observing station. [1] |
| 4034 | Station: Control | See control. [14] |
| 4035 | Station: Laplace | A triangulation or traverse station at which a laplace azimuth is determined. At a laplace station both astronomical longitude and astronomical azimuth are determined. [14] |
| 4036 | Stationary Front | A front that is nearly stationary with winds blowing almost parallel and from opposite directions on each side of the front. [1] |
| 4037 | Steering Compass | See compass. [14] |
| 4038 | Stellar Parallax | See parallax: annual. [14] |
| 4039 | Stereocomparator | In photogrammetry, a stereoscopic instrument for measuring parallax; usually includes a means of measuring photograph coordinates of image points. [14] |
| 4040 | Storm High Water | See high water. [14] |
| 4041 | Stream: Outgoing | See ebb stream. [14] |
| 4042 | Submarine Sentry | A form of underwater kite towed at a predetermined constant depth in search of elevations of the bottom. The kite rises to the surface upon encountering an obstruction. [14] |
| 4043 | Submarine Spring | See spring. [14] |
| 4044 | Submarine Valley | See valley. [14] |
| 4045 | Substellar Point | The geographical position of a star; that point on the surface of the earth at which the star is in the zenith at a specified time. Also called subastral point. [14] |
| 4046 | Suction Vortices | Small, rapidly rotating whirls perhaps 10 m in diameter that are found within large tornadoes. [1] |
| 4047 | Superior Transit | See meridian transit. [14] |
| 4048 | Survey: Magnetic | A survey conducted to measure the strength and direction of the earth's magnetic field at specific points on or near the surface of the earth. [14] |
| 4049 | Survey: Offshore | Hydrographic surveys conducted in areas beyond a certain distance from the shore, e.g. In the high seas. [14] |
| 4050 | Survey: Revisory | Hydrographic surveys conducted for the revision of charts including checking depths, aids to navigation, existence of land and water features, and any changes or additions such as new features constructed that are important to the mariner. A revisory survey is not considered to be a detailed resurvey. [14] |
| 4051 | Surveying: Plane | A branch of the art of surveying in which the surface of the earth is considered a plane surface. In plane surveying, curvature of the earth is neglected, and computations are made using the formulae of plane geometry and plane trigonometry. [14] |
| 4052 | Tape Thermometer | See under thermometer. [14] |
| 4053 | Telemeteorograph | General term for meteorological instruments whose indications are recorded at a distance. [14] |
| 4054 | Telltale Compass | See compass. [14] |
| 4055 | Terrestrial Pole | See pole. [14] |
| 4056 | Thermohygrograph | See hygrothermograph. [14] |
| 4057 | Tidal Prediction | See tide prediction. [14] |
| 4058 | Tide(S): Apogean | Tides of decreased range occurring when the moon is near apogee. [14] |
| 4059 | Tide: Single Day | See tide: diurnal. [14] |
| 4060 | Time: Local Mean | The mean solar time for the meridian of the observer. [14] |
| 4061 | Time: Mean Solar | Time measured by the diurnal motion of the mean sun, which is supposed to move uniformly in the celestial equator, completing the circuit in one tropical year. Often termed simply mean time. [14] |
| 4062 | Time: True Solar | See time: apparent solar. [14] |
| 4063 | Topography Board | See field board. [14] |
| 4064 | Tornado Outbreak | A series of tornadoes that forms within a particular region?a region that may include several states. Often associated with widespread damage and destruction. [1] |
| 4065 | Transit Traverse | See traverse. [14] |
| 4066 | Transition Layer | A water layer with a distinct change of the vertical gradient of a given parameter relative to adjacent layers. [14] |
| 4067 | Traverse Sailing | See sailing. [14] |
| 4068 | Traverse Station | See station. [14] |
| 4069 | Traverse: Closed | A traverse which starts and ends upon the same station, or upon stations whose relative positions have been determined by other surveys. [14] |
| 4070 | Tropic Of Cancer | The northern parallel of declination, approximately 23°27' from the celestial equator, reached by the sun at its maximum northerly declination, or the corresponding parallel on the earth. [14] |
| 4071 | Turn Of The Tide | See change of tide. [14] |
| 4072 | Underground Mark | A station mark set and plumbed below the center of a surface mark and separated therefrom so as to preserve the station in case of accident to the surface mark. Also called subsurface mark. [14] |
| 4073 | Watch: Comparing | A hack watch, particularly one having its error determined by comparison with a chronometer. [14] |
| 4074 | Water Turbulence | The disturbance of water caused by the interaction of any combination of waves, currents, tidal streams, wind, shoal patches and obstructions. [14] |
| 4075 | Wave Forecasting | The theoretical determination of future wave characteristics; usually from observed or predicted meteorological or oceanographic phenomena. [14] |
| 4076 | Wave: Modulating | A wave which modulates a carrier wave. [14] |
| 4077 | Wave: Transverse | A wave in which the direction of propagation of the wave is normal to the displacements of the medium, for example, a vibrating string. The gravity wave in which fluid parcels move in circular orbits is an example of a mixed transverse-longitudinal wave. [14] |
| 4078 | Wave: Trochoidal | A progressive oscillatory wave whose form is that of a prolate cycloid or trochoid. It is approximated by waves of small amplitudes. [14] |
| 4079 | Wave: Ultrashort | A radio wave shorter than 10 meters. [14] |
| 4080 | Wind-Chill Index | The cooling effect of any combination of temperature and wind, expressed as the loss of body heat. Also called wind-chill factor. [1] |
| 4081 | Wire Drag Survey | See survey. [14] |
| 4082 | Working Pendulum | See pendulum. [14] |
| 4083 | Zenith Telescope | See telescope. [14] |
| 4084 | Zero Sounding(S) | See sounding. [14] |
| 4085 | Zone: Equisignal | That region in space within which the difference in amplitude of two radio signals (usually emitted by a single station) is indistinguishable. [14] |
| 4086 | Absolute Accuracy | See accuracy: absolute. [14] |
| 4087 | Acoustic Sounding | See echo sounding. [14] |
| 4088 | Adjusted Position | See position. [14] |
| 4089 | Aerial Navigation | See navigation: air. [14] |
| 4090 | Alignment Of Base | The laying out of a base line in correct alignment by means of a theodolite and range poles, before the length of the line is measured. [14] |
| 4091 | Almanac: Nautical | An annual publication containing various computed astronomical data primarily intended for use in marine navigation. See also ephemeris. [14] |
| 4092 | Altitude: Sextant | The altitude as indicated by a sextant before corrections are applied. [14] |
| 4093 | Amphidromic Point | A no-tide point, from which cotidal lines radiate. [14] |
| 4094 | Anchorage Buoy(S) | Buoy(s) marking the limits of an anchorage. [14] |
| 4095 | Angle: Conversion | See arc to chord correction. [14] |
| 4096 | Annual Inequality | Seasonal variation in water level or tidal current speed, more or less periodic, due chiefly to meteorological causes. [14] |
| 4097 | Anomaly: Magnetic | See local magnetic disturbance. [14] |
| 4098 | Antenna: Screened | Any antenna which is screened in some way to counteract disturbances. [14] |
| 4099 | Apochromatic Lens | A lens that has been corrected for chromatic aberration for at least three colors. [14] |
| 4100 | Apparent Altitude | See altitude: apparent. [14] |
| 4101 | Apparent Position | See position. [14] |
| 4102 | Arc Of Visibility | The arc of a light sector designated by its limiting bearings in which a light is visible as viewed from a vessel. [14] |
| 4103 | Arc: Astronomical | The apparent arc described above (diurnal arc) or below (nocturnal arc) the horizon by the sun or another celestial body. [14] |
| 4104 | Articulated Light | See articulated beacon. [14] |
| 4105 | Artificial Island | See installation offshore. [14] |
| 4106 | Automatic Plotter | See plotter. [14] |
| 4107 | Azimuth: Geodetic | For the geodesic line from a to b, the angle between the tangent to the meridian at a and the tangent to the geodesic line at a. This azimuth is called the forward azimuth for the line ab. See azimuth: back. [14] |
| 4108 | Azimuth: Magnetic | At the point of observation, the angle between the vertical plane through the observed object and the vertical plane in which a freely suspended symmetrically magnetized needle, influenced by no transient artificial magnetic disturbance, will come to rest. [14] |
| 4109 | Band Of Frequency | The range of frequency between two specific limits. Also called frequency band. [14] |
| 4110 | Barometer: Marine | Mercury barometer used on board ships, characterized by a constriction in the tube in order to damp out oscillations of the mercury caused by the movements of the ship. [14] |
| 4111 | Basal Orientation | See orientation. [14] |
| 4112 | Beacon: Responder | See transponder beacon. [14] |
| 4113 | Bearing: Acoustic | See bearing: sonic. [14] |
| 4114 | Bearing: Magnetic | Bearing relative to magnetic north. Compass bearing corrected for magnetic deviation. [14] |
| 4115 | Bearing: Relative | Bearing relative to the heading of a craft. [14] |
| 4116 | Bessel'S Spheroid | See reference spheroid. [14] |
| 4117 | Boundary Monument | A material object placed on or near a boundary line to preserve and identify the ground location of the boundary line. Where it is impracticable to establish a monument on or very close to a boundary line, the position of the boundary line on the ground is preserved by means of reference marks. The term monument is sometimes used to include both the mark on the boundary and the reference mark. [14] |
| 4118 | Breaking Of Waves | Disintegration of a wave which breaks with foam in shallows whose gradient is more or less regular. An incomplete breaking can likewise result from a sudden reduction in depth. [14] |
| 4119 | Broad On The Beam | Bearing 090° relative (broad on the starboard beam) or 270° relative (broad on the port beam). If the bearings are approximate, the expression on the beam or abeam should be used. See also on the beam. [14] |
| 4120 | Buoy: Bifurcation | A distinctive lateral buoy used to indicate both the point at which a channel divides and the channel that has been designated as preferred channel. [14] |
| 4121 | Buoy: Radiobeacon | A buoy equipped with a marker radio beacon. [14] |
| 4122 | Cable: Degaussing | Cable carrying an electric current for degaussing a vessel. [14] |
| 4123 | Camera: Ballistic | A precision terrestrial camera usually employing glass plates, used at night to photograph such objects as rockets or satellites against a star background. If the camera is mounted so that it tracks the stars or the object, it may be called a tracking camera. [14] |
| 4124 | Canyon: Submarine | A relatively narrow, deep depression with steep slopes, the bottom of which grades continuously downward. [14] |
| 4125 | Celestial Concave | See celestial sphere. [14] |
| 4126 | Centripetal Force | The force directed towards the center of curvature which constrains a body to move in a curved path. Equal and opposite to the centrifugal force. [14] |
| 4127 | Chart Compilation | The production of a new or revised map or chart, or portions thereof, from existing maps, aerial photographs, surveys, new data and other sources or the selection, assembly, and graphic representation of all relevant information required for the preparation of a map or chart. [14] |
| 4128 | Clamshell Snapper | See snapper. [14] |
| 4129 | Clarke'S Spheroid | See reference spheroid. [14] |
| 4130 | Clearance: Bridge | Minimum vertical or horizontal space available for passage. [14] |
| 4131 | Climatic Controls | The relatively permanent factors that govern the general nature of the climate of a region. [1] |
| 4132 | Closure: Error Of | See error of closure. [14] |
| 4133 | Collector Tracing | A comprehensive record of the work compiled while the hydrographic survey is in progress. [14] |
| 4134 | Colour Separation | Either the process of preparing a separate drawing, engraving or negative for each colour required in the production of a chart or a photographic process or electronic scanning procedure using colour filters to separate a multi-colored copy into separate images of each of the three primary colors. [14] |
| 4135 | Compass Needle(S) | Magnetized steel needle(s) of high retentivity that tends to keep north-south line of compass card in magnetic meridian. [14] |
| 4136 | Compass: Deadbeat | An aperiodic compass; one that, when deflected, returns by one direct movement to its proper reading. [14] |
| 4137 | Compass: Inverted | See compass: hanging. [14] |
| 4138 | Compass: Magnetic | A compass depending for its directive force upon the attraction of the magnetism of the earth for a magnet free to turn in an horizontal direction. [14] |
| 4139 | Compass: Overhead | See compass: hanging. [14] |
| 4140 | Compass: Standard | A compass designated as the standard for a vessel. It is located in a favorable position and is accurately calibrated. [14] |
| 4141 | Composite Sailing | See sailing. [14] |
| 4142 | Computer: Digital | A machine for carrying out mathematical processes by operations based on counting, as distinct from an analogue computer. [14] |
| 4143 | Control: Geodetic | A system of control stations established by geodetic methods. See survey: geodetic. [14] |
| 4144 | Control: Vertical | Control determined in elevation relative to a datum plane. [14] |
| 4145 | Controlling Depth | See depth. [14] |
| 4146 | Conversion Factor | That factor by which the numerical value made in one system of units must be multiplied to arrive at the numerical value in another system of units. [14] |
| 4147 | Coordinates: Grid | A plane rectangular coordinate system based on, and mathematically adjusted to, a map projection, so that geographic positions in terms of latitude and longitude can be readily transformed into plane coordinates, and the computation relating to them made by the ordinary methods of plane surveying. [14] |
| 4148 | Critical Sounding | The least depth in proximity to a known or potential navigational route. [14] |
| 4149 | Current: Backrush | A gradient current caused by the rise of water level near shores and in sea reaches. [14] |
| 4150 | Current: Gradient | A current due to the horizontal component of the hydrostatic pressure gradient. [14] |
| 4151 | Current: Nontidal | Any current that is caused by other than tide producing forces. See also stream. [14] |
| 4152 | Current: Periodic | An oscillating current the values of which recur at somewhat regular intervals. [14] |
| 4153 | Current: Residual | The mean current without periodic components. [14] |
| 4154 | Current: Seasonal | A current which has large changes in speed or direction due to seasonal winds. [14] |
| 4155 | Day: Astronomical | A mean solar day beginning at noon. [14] |
| 4156 | Declination: Grid | See grid. [14] |
| 4157 | Depth Differences | Those differences in depth which may be encountered in hydrographic surveys at crossing of cross lines and principal lines of soundings. [14] |
| 4158 | Detached Position | See position. [14] |
| 4159 | Detached Sounding | See sounding. [14] |
| 4160 | Difference: Tidal | See tidal difference. [14] |
| 4161 | Differential Mode | A method of accurate positioning; transmissions of an electromagnetic position fixing system are received at known positions ashore and the offsets between absolute known positions and system positions are transmitted to the ship in the vicinity. The offsets are applied to the measurements of the ship's receiver. [14] |
| 4162 | Direction Of Tilt | The direction (azimuth) of the principal plane of a photograph. Also, the direction of the principal line on a photograph. [14] |
| 4163 | Direction Of Wind | Direction from which the wind blows. Also called wind direction. [14] |
| 4164 | Dissipating Stage | The final stage in the development of an ordinary cell thunderstorm when downdrafts exist throughout the cumulonimbus cloud. [1] |
| 4165 | Double High Water | See high water. [14] |
| 4166 | Doubtful Sounding | See sounding. [14] |
| 4167 | Ecliptic Latitude | See latitude: celestial. [14] |
| 4168 | Eotvos Correction | A correction applied to gravity measurements to balance the effect of the vertical force experienced by a body moving in an east-west direction on the rotating earth. [14] |
| 4169 | Equation: Laplace | An equation which expresses the relationships between astronomic azimuth, geodetic azimuth, and the astronomic longitude and geodetic longitude. [14] |
| 4170 | Equator: Geodetic | The line on the spheroid connecting points of 0° geodetic latitude. [14] |
| 4171 | Equator: Magnetic | That line on the surface of the earth connecting all points at which the magnetic dip is zero. Also called aclinic line. [14] |
| 4172 | Equidistance Line | See median line. [14] |
| 4173 | Equinoctial Point | See equinox. [14] |
| 4174 | Erecting Eyepiece | See eyepiece. [14] |
| 4175 | Error: Accidental | An error whose occurrence depends on the law of chance only. Also calledrandom erroror irregular error. [14] |
| 4176 | Error: Systematic | An error whose magnitude changes in proportion to known changes in observational conditions. Also called regular error. [14] |
| 4177 | Evaluation Report | A report which summarizes pertinent facts relating to a given hydrographic survey. Included in the report are sections which address the quality of the hydrographic survey and detailed comparisons made with prior hydrographic surveys and the appropriate nautical chart. Specific evaluations and recommendations regarding the adequacy of the survey to supersede prior survey data and charted information are made. [14] |
| 4178 | Exposure Interval | The time interval between the taking of successive photographs. [14] |
| 4179 | First Nodal Point | See nodal point. [14] |
| 4180 | Focal-Plane Plate | A glass plate set in the camera so that the surface away from the lens coincides with the focal plane. Its purpose is to position the emulsion of the film in the focal plane when the film is physically pressed into contact with the glass plate. Also called contact glass or contact plate. [14] |
| 4181 | Fog Signal: Radio | A regularly recurring distinctive signal sent out by a radio beacon during thick weather. [14] |
| 4182 | Forced Convection | See convection. [14] |
| 4183 | Frequency Channel | See channel. [14] |
| 4184 | Front Nodal Point | See nodal point. [14] |
| 4185 | Geodetic Position | See position. [14] |
| 4186 | Geologic(Al) Time | See time. [14] |
| 4187 | Grid: Parallactic | In photogrammetry, a uniform pattern of rectangular lines drawn or engraved on some transparent material, usually glass, and placed either over the photographs of a stereoscopic pair or in the optical system of a stereoscope, in order to provide a continuous floating-mark system. [14] |
| 4188 | Grid: Perspective | In photogrammetry, a network of lines, drawn or superimposed on a photograph, to represent the perspective of a systematic network of lines on the ground or datum plane. See also grid method. [14] |
| 4189 | Groin (Or Groyne) | A low artificial wall-like structure of durable material extending from the land to seaward for a particular purpose, such as to protect the coast or to force a current to scour a channel. Sometimes called arip-rap in new england waters. [14] |
| 4190 | Ground Resolution | See resolution. [14] |
| 4191 | Hemispherical Map | See map. [14] |
| 4192 | High Water: Storm | The highest level to which the sea rises during a storm and usually marked by a line of debris high up on the beach. [14] |
| 4193 | Horizon: Rational | See horizon: celestial. [14] |
| 4194 | Horizon: Sensible | That circle of the celestial sphere formed by the intersection of the celestial sphere and a plane through any point, such as the eye of an observer, and perpendicular to the zenith-nadir line. [14] |
| 4195 | Hurricane Hunters | A popular term for aircraft and/or personnel engaged in the reconnaissance of hurricanes (tropical cyclones). [1] |
| 4196 | Hurricane Warning | A warning given when it is likely that a hurricane will strike an area within 24 hours. [1] |
| 4197 | Hydrologic Series | Simultaneous observations carried out to obtain oceanographic data at specified levels. [14] |
| 4198 | Hypsometric Curve | See hypsographic curve. [14] |
| 4199 | Hypsometric Tints | A succession of shades or colour graduations used to depict ranges of elevations. Also called gradient tints or elevation tints. [14] |
| 4200 | Ice Concentration | In sea ice reporting, the ratio of the areal extent of ice present to the total areal extent of ice and water. Concentration is usually reported in tenths. Also called ice cover. [14] |
| 4201 | Ionospheric Storm | Violent changes in the state of the ionosphere. [14] |
| 4202 | Isostatic Anomaly | The difference between an observed value of gravity and a theoretical value at the point of observation which has been corrected for elevation of the station above the geoid and for the effect of topography over the whole earth, and for its isostatic compensation. [14] |
| 4203 | Labour (Or Labor) | (v.i.). To pitch and roll heavily under conditions which subject the ship to unusually heavy stresses caused by confused or turbulent seas or unstable stowage or cargo. [14] |
| 4204 | Lake-Effect Snows | Localized snowstorms that form on the downwind side of a lake. Such storms are common in late fall and early winter near the great lakes as cold, dry air picks up moisture and warmth from the unfrozen bodies of water. [1] |
| 4205 | Latitude: Reduced | See latitude: parametric. [14] |
| 4206 | Level: Bull'S Eye | See level: spirit. [14] |
| 4207 | Levelling: Direct | The determination of differences of elevation by a continuous series of short horizontal lines. Vertical distances from these lines to adjacent ground marks are determined by direct observations on graduated rods with a levelling instrument equipped with a spirit level. [14] |
| 4208 | Levelling: Spirit | The determination of elevations of points with respect to each other or with respect to a common datum, by use of a levelling rod and an instrument using a spirit level to establish a horizontal line of sight. [14] |
| 4209 | Light(S): Leading | Two or more lights associated so as to form a leading line to be followed. [14] |
| 4210 | Light: Aeromarine | A marine-type light in which a proportion of the beam is deflected to an angle of 10°-15° above the horizon for the use of aircraft. [14] |
| 4211 | Light: Morse Code | A rhythmic light in which appearances of light of two clearly different durations are grouped to represent a character or characters in the morse code. [14] |
| 4212 | Light: Occasional | A light not regularly exhibited. [14] |
| 4213 | Light: Undulating | A continuously luminous light which alternatively increases and decreases in brightness in cyclic sequence. [14] |
| 4214 | Longitudinal Wave | See wave. [14] |
| 4215 | Low Water: Double | A low water consisting of two minima separated by a relatively small elevation. See tide: double. [14] |
| 4216 | Lower Culmination | See meridian transit. [14] |
| 4217 | Magnetic Latitude | See latitude. [14] |
| 4218 | Marine Stabilizer | See stabilizer. [14] |
| 4219 | Mean Sphere Depth | The uniform depth to which the water would cover the earth if the solid surface were smoothed off and were parallel to the surface of the geoid. The accepted figure for this depth is 2,440 meters. The mean depth of the sea is 3,800 meters. [14] |
| 4220 | Mean Spring Range | See spring range. [14] |
| 4221 | Mean Square Error | See error. [14] |
| 4222 | Measured Distance | A course at sea, whose ends are indicated by ranges ashore, and whose length has been accurately measured for determining the speed of vessels. [14] |
| 4223 | Mercury Barometer | A type of barometer that uses mercury to measure atmospheric pressure. The height of the mercury column is a measure of atmospheric pressure. [1] |
| 4224 | Meridian: Central | See meridian: initial. [14] |
| 4225 | Meridian: Compass | A line through the north-south points of a magnetic compass. The compass card axis lies in the compass meridian. [14] |
| 4226 | Meridian: Initial | A meridian through the origin of a system of grid coordinates and used as y-axis of the system. Also called central meridian. [14] |
| 4227 | Method Of Squares | See squares: method of. [14] |
| 4228 | Micrometer: Filar | A device attached to a telescope or microscope, consisting of a wire thread (filament) connected with a screw in such manner that as the screw is turned, the wire moves through a continuous succession of parallel positions, all in the focal plane of the instrument. Any small angle may be measured by noting the number of turns and fractions of a turn of the screw which are made in moving the wire from one bisection to another, and multiplying this by the value of one turn. See micrometer: ocular, micrometer microscope, and micrometer comb. [14] |
| 4229 | Modulation: Pulse | The process of forming very short bursts of a carrier wave, separated by relatively long periods during which no carrier wave is transmitted. [14] |
| 4230 | Modulation: Space | The combining of signals in space to form a signal of desired characteristics. [14] |
| 4231 | Moment Of Inertia | The quantity obtained by multiplying the mass of each small part of a body by the square of its distance from an axis, and adding all the results. [14] |
| 4232 | Multiple Echo(Es) | See echo. [14] |
| 4233 | Nadir: Photograph | In photogrammetry, the point at which a vertical line through the perspective center of the camera lens pierces the plane of the photograph. Also called nadir point, or plumb point. [14] |
| 4234 | Natural Frequency | See frequency. [14] |
| 4235 | Nautical Twilight | See twilight. [14] |
| 4236 | Navigation: Astro | See navigation: celestial. [14] |
| 4237 | Navigation: Radio | See navigation: electronic. [14] |
| 4238 | Negative Gradient | In oceanography, a layer of water where temperature decreases with depth. [14] |
| 4239 | Nitric Oxide (No) | A colorless gas produced by natural bacterial action in soil and by combustion processes at high temperatures. In polluted air, nitric oxide can react with ozone and hydrocarbons to form other substances. In this manner, it acts as an agent in the production of photochemical smog. [1] |
| 4240 | No-Check Position | See station: intersection. [14] |
| 4241 | Nodal Point: Rear | See nodal point. [14] |
| 4242 | Observation Tower | A tower from which one's surroundings can be observed, but at which a watch is not habitually maintained, as at a lookout tower. Such towers are temporarily erected for observations in geodetic networks. [14] |
| 4243 | Obstruction Light | See light. [14] |
| 4244 | Ocular Micrometer | See micrometer. [14] |
| 4245 | Opacity (Optical) | The ratio of the incident to the transmitted (or reflected) light. It varies with the use of scattered or specular light. [14] |
| 4246 | Open End Traverse | See traverse: open. [14] |
| 4247 | Orographic Uplift | The lifting of air over a topographic barrier. Clouds that form in this lifting process are called orographic clouds. [1] |
| 4248 | Pair Of Compasses | See compass. [14] |
| 4249 | Parallactic Error | See error. [14] |
| 4250 | Parallax: Angular | See parallactic angle. [14] |
| 4251 | Parallax: Optical | See parallax: instrumental. [14] |
| 4252 | Parallel Sounding | A system of surveying in which the mother vessel takes soundings while following a given course; at the same time an array of satellite boats takes soundings along parallel courses at a fixed distance from the mother vessel. The satellite boats determine their position relative to the mother vessel. The term is also employed when a single vessel takes multiple lines of soundings with transducers arranged at regular intervals on outriggers. [14] |
| 4253 | Particle Velocity | In ocean wave studies, the instantaneous velocity of a water particle undergoing orbital motion. At the crest, its direction is the same as the direction of progress of the wave, and at the trough it is in the opposite direction. [14] |
| 4254 | Passage: Meridian | See meridian transit. [14] |
| 4255 | Pendulum: Working | A pendulum which is used (swung) in a determination of the intensity of gravity. [14] |
| 4256 | Permanent Current | See current. [14] |
| 4257 | Photograph Centre | The center of a photograph as indicated by the images of the fiducial mark or marks of the camera. In a perfectly adjusted camera the photograph center and the principal point are identical. [14] |
| 4258 | Photohead Plotter | A device used to plot information by exposure of a photographic film. [14] |
| 4259 | Pinnacled Iceberg | An iceberg weathered in such manner as to produce spires or pinnacles. Also called pyramidal iceberg, irregular iceberg. [14] |
| 4260 | Plane: Horizontal | A plane perpendicular to the direction of gravity; any plane tangent to the geoid or parallel to such a plane. In surveying, a plane perpendicular to the plumb line within which or on which angles and distances are observed. [14] |
| 4261 | Pole: Terrestrial | One of the poles of the earth. See pole. [14] |
| 4262 | Position Doubtful | Of uncertain position. The expression is used principally on charts to indicate that a wreck, shoal, etc., has been reported in various positions and not definitely determined in any. Usually shown by the abbreviation 'pd'. [14] |
| 4263 | Position: Assumed | A point at which a craft is assumed to be located, particularly one used as preliminary to establishing certain navigational data, as that point of the surface of the earth for which the computed altitude is determined in the solution of a celestial observation. [14] |
| 4264 | Positive Gradient | In oceanography, a positive rate of change with depth. [14] |
| 4265 | Potential Density | In oceanography, the density that a parcel of water would have if raised adiabatically to the surface, that is, if determined from the parcel's 'in situ' salinity and potential temperature. [14] |
| 4266 | Predicted Tide(S) | See tide. [14] |
| 4267 | Pressure-Altitude | An atmospheric pressure expressed in terms of altitude which corresponds to that pressure in the standard atmosphere. [14] |
| 4268 | Quadrantal Sphere | See quadrantal correctors. [14] |
| 4269 | Radial Distortion | See under distortion. [14] |
| 4270 | Radio Time Signal | A time signal sent by radio. [14] |
| 4271 | Radio Transmitter | Equipment for generating radio signals. [14] |
| 4272 | Recommended Route | See route: recommended. [14] |
| 4273 | Refraction: Angle | See angle of refraction. [14] |
| 4274 | Relative Accuracy | See accuracy: relative. [14] |
| 4275 | Relative Aperture | See aperture: relative. [14] |
| 4276 | Relief: Submarine | Inequalities of the ocean bed, or their representation on a chart. [14] |
| 4277 | Resection Station | See station. [14] |
| 4278 | Reversing Current | See current. [14] |
| 4279 | Roll (Or Rolling) | The oscillation of a ship about the longitudinal axis. In photogrammetry, a rotation of a camera or a photograph-coordinate system about either the photograph x axis or the exterior x axis. [14] |
| 4280 | Sailing: Mercator | A mathematical solution of the plot as made on a Mercator chart. It is similar to plane sailing, but uses meridional difference and difference of longitude in place of difference of latitude and departure, respectively. [14] |
| 4281 | Sailing: Meridian | Following a true course of 0° or 180°; sailing along a meridian. [14] |
| 4282 | Sailing: Parallel | A method of converting departure into difference of longitude, or vice versa, when the true course is 90° or 270°. [14] |
| 4283 | Sailing: Traverse | A method of determining the equivalent course and distance made good by a craft following a track consisting of a series of rhumb lines. The problem is customarily solved by the principles of plane sailing. [14] |
| 4284 | Saint Elmo'S Fire | Faintly luminous electrical discharge in the atmosphere: this discharge, more or less continuous and of slight or moderate intensity, emanates from objects which present a high surface electric field, in particular from points and sharp edges. [14] |
| 4285 | Satellite Geodesy | See geodesy. [14] |
| 4286 | Satellite Station | See eccentric station. [14] |
| 4287 | Scale: Equivalent | The relationship which a small distance on a map, chart or graphic bears to the corresponding distance on the earth, expressed as an equivalence. [14] |
| 4288 | Scale: Fractional | See scale: natural. [14] |
| 4289 | Scale: Log Factor | In hydrographic surveys, a proportional diagram constructed for the scale of the survey sheet by means of which the log factor can be quickly determined. [14] |
| 4290 | Scale: Particular | The relation between an infinitesimal linear distance in any direction at any point on a map projection and the corresponding linear distance on a globe. [14] |
| 4291 | Seabed Topography | See topography. [14] |
| 4292 | Secondary Station | See station: supplementary. [14] |
| 4293 | Secondary Tide(S) | See tide. [14] |
| 4294 | Sector Scan Sonar | A horizontal aperture sonar used to detect obstructions ahead of the vessel by mechanical or electronic scanning in the horizontal plane. [14] |
| 4295 | Sedimentary Rocks | Rocks formed by the accumulation of sediment in water (aqueous deposits) or from air (eolian deposits). The sediments may consist of rock fragments or particles of various sizes (conglomerate, sandstone, shale); of the remains or products of animals or plants (certain limestones and coal); of the product of chemical action or of evaporation (salt, gypsum, etc.); or of mixture of these materials. [14] |
| 4296 | Semi-Arid Climate | A dry climate where potential evaporation and transpiration exceed precipitation. Not as dry as the arid climate. Typical vegetation is short grass. [1] |
| 4297 | Semi-Enclosed Sea | See enclosed sea. [14] |
| 4298 | Separation Effect | In echo sounding instruments with separate transmitting and receiving units, the effect caused by such separation. This introduces an error depending on the distance between the acoustic units and varying with the depth of water. Such error makes the registered depth greater than the actual depth. Separation also causes a lag in registration of the transmitted signal. [14] |
| 4299 | Sextant: Pendulum | A sextant provided with a pendulum to indicate the horizontal. [14] |
| 4300 | Sextometer Method | A substitute for plane table traverse for short distances in unimportant areas where the use of the plane table is impracticable and the survey party operates in a launch. Azimuth is carried forward by means of angles accurately measured with a sextant. Distance is determined by measuring, also with the sextant, the small horizontal angle between fixed targets on a special rod held horizontally. The angle may be converted into a distance by means of a hypsography. [14] |
| 4301 | Signal: Eccentric | See eccentric signal. [14] |
| 4302 | Signal: Longitude | A sign indicating a time event, observable at different stations, and used in comparing local times of those stations, and determining the difference of their longitudes. [14] |
| 4303 | Skewed Projection | See projection. [14] |
| 4304 | Small Craft Chart | Chart designed for easy reference and plotting in limited spaces. It portrays regular nautical chart detail and other specific details of special interest to the small craft operator, such as enlargements of harbors; tide, current and weather information; rules of the road information; locations of marine facilities; anchorages; courses; and distances. [14] |
| 4305 | Solsticial Colure | See colure: solsticial. [14] |
| 4306 | Sounding Interval | The interval between successive soundings along a line of sounding. See density of soundings. [14] |
| 4307 | Sounding(S): Zero | (US Terminology). Soundings that reduce to heights above the sounding datum but shown on the smooth sheet as zero soundings regardless of height. A practice now discontinued. See sounding: minus. [14] |
| 4308 | Sounding: Line Of | See line of sounding. [14] |
| 4309 | Space Coordinates | See coordinates. [14] |
| 4310 | Spherical Sailing | See sailing. [14] |
| 4311 | Spoil Ground Buoy | A buoy marking the limit of a spoil ground. [14] |
| 4312 | Station: Magnetic | The geographic location at which any set of magnetic observations was taken. [14] |
| 4313 | Station: Traverse | A definite point on the earth whose position has been determined from another known point by linear measurements controlled in azimuth by angular measurements. [14] |
| 4314 | Steering Repeater | A compass repeater by which a craft is steered. See also compass: steering. [14] |
| 4315 | Stereocompilation | See compilation. [14] |
| 4316 | Still Water Level | The level that the sea surface would assume in the absence of wind waves; not to be confused with mean sea level or half-tide level. [14] |
| 4317 | Submarine Volcano | A seabed volcano, submerged at the chart sounding datum, which may or may not be active. [14] |
| 4318 | Substitute Centre | A point which, because of its ease of identification on overlapping photographs, is used instead of the principal point as a radial center. [14] |
| 4319 | Sunshine Recorder | See heliograph. [14] |
| 4320 | Survey: Cadastral | A survey relating to land boundaries and subdivisions, made to create units suitable for transfer or to define the limitations of title. Also called land survey. [14] |
| 4321 | Survey: Wire-Drag | A hydrographic survey made utilizing a wire drag. In areas of rocky bottom or where submerged obstacles such as wrecks are present, a wire-drag survey represents the most practical way of making sure that all obstructions or dangers have been found and least depths over them obtained. Also called wire drag sweep. [14] |
| 4322 | Surveying Sextant | See sextant: sounding. [14] |
| 4323 | Synoptic Analysis | See weather analysis. [14] |
| 4324 | Synoptic Forecast | Weather forecast based on synoptic observation. [14] |
| 4325 | Taut Wire Mooring | A mooring arrangement in which a submerged float provides the upward force necessary to maintain the system in a fixed position with reference to the sea bottom. [14] |
| 4326 | Telescope: Zenith | An astronomical instrument for determining the latitude by observing zenith distances of two stars that culminate as close as possible in time, and at nearly the same altitude on opposite sides of the zenith. [14] |
| 4327 | Terrestrial Globe | See globe. [14] |
| 4328 | Theoretical Error | See error. [14] |
| 4329 | Thermometer: Tape | A precision thermometer fitted in a specially designed case to clip on and against a metal tape in order to determine temperature corrections for precision base or traverse tape measurements. [14] |
| 4330 | Tide(S): Perigean | Tides of increased range occurring when the moon is near perigee. [14] |
| 4331 | Tide: Equilibrium | A hypothetical tide based upon the assumption that the water responds, instantly to the tide-producing forces of the moon and sun, and forms a surface of equilibrium under the action of these forces, disregarding friction, inertia and the irregular distribution of the land masses. [14] |
| 4332 | Tide: Mid-Extreme | A level midway between the extreme high water and extreme low water occurring at a place. See half-tide level. [14] |
| 4333 | Tide: Semidiurnal | A tide in which the tidal cycle consists of two high waters and two low waters each tidal day, with comparatively little diurnal inequality. [14] |
| 4334 | Topographic Model | See relief model. [14] |
| 4335 | Traverse: Hanging | See traverse: open. [14] |
| 4336 | Traverse: Transit | A traverse in which the angles are measured with a transit or theodolite and the lengths with a suitable measuring device. [14] |
| 4337 | Triangle Of Error | See cocked hat. [14] |
| 4338 | Turbidity Current | See current. [14] |
| 4339 | Upper Culmination | Upper transit. [14] |
| 4340 | Urban Heat Island | The increased air temperatures in urban areas as contrasted to the cooler surrounding rural areas. [1] |
| 4341 | Valley: Submarine | A relatively shallow wide depression, the bottom of which usually has a continuous gradient. This term is generally not used for features that have canyon-like characteristics for a significant portion of their extent. [14] |
| 4342 | Vertical Light(S) | See light. [14] |
| 4343 | Vertical Parallax | See parallax: y-. [14] |
| 4344 | Wave Interference | The phenomenon which results when waves of the same or nearly the same frequency are superposed. It is characterized by a spatial or temporal distribution of amplitude of some specified characteristic differing from that of the individual superposed waves. [14] |
| 4345 | Wave(S): Periodic | Waves which are repeated at regular intervals. [14] |
| 4346 | Wave: Oscillatory | A wave in which each individual particle oscillates about a point with little or no permanent change in position. The term is commonly applied to progressive oscillatory waves in which only the form advances, the individual particles moving in closed orbits, as ocean waves in deep waters. Distin-guished from a wave of translation. [14] |
| 4347 | Wave: Progressive | A wave which is manifested by the progressive movement of the wave form. The opposite is a standing wave. Also called travelling wave. [14] |
| 4348 | Wave: Propagation | The travel of waves through or along a medium. [14] |
| 4349 | Well: Development | A borehole drilled, usually from a production platform, after an oil field or gas field has been judged capable of economic production. [14] |
| 4350 | Year: Anomalistic | The period of one revolution of the earth around the sun, from perihelion to perihelion, averaging 365 days, 6 hours, 13 minutes, 53.0 seconds in 1900, and increasing at the rate of 0.26 second per century. [14] |
| 4351 | Accuracy: Absolute | The evaluation of all errors encountered in defining the position of a single feature or point on a geodetic datum or system. [14] |
| 4352 | Accuracy: Relative | The evaluation of the random errors in determining the positional orientation of one point or feature with respect to another. [14] |
| 4353 | Aeronautical Chart | See chart. [14] |
| 4354 | Altitude: Meridian | The altitude of a celestial body when it is on the celestial meridian of the observer. [14] |
| 4355 | Altitude: Observed | The sextant altitude of a celestial body after all corrections (see altitude: apparent) have been applied. In american terminology the term is usually employed in the place of true altitude. [14] |
| 4356 | Angle: Parallactic | See parallactic angle. [14] |
| 4357 | Angular Distortion | See distortion. [14] |
| 4358 | Aperture: Relative | For a photographic or telescopic lens, the ratio of the equivalent focal length to the diameter of the entrance pupil. Expressed as f: 4.5; also called f-number, f-stop, or speed of lens. [14] |
| 4359 | Apparent Solar Day | See day: solar. [14] |
| 4360 | Archipelagic Apron | A gentle slope with a generally smooth surface of the sea floor, characteristically found around groups of islands or seamounts. [14] |
| 4361 | Area To Be Avoided | A routing measure comprising an area within defined limits in which either navigation is particularly hazardous or it is exceptionally important to avoid casualties and which should be avoided by all ships, or certain classes of ships. [14] |
| 4362 | Articulated Beacon | A vertical pipe structure that oscillates around a universal coupling connected to a sinker. The structure is kept upright by the buoyancy of a submerged floating chamber. Primarily designed to mark narrow channels with greater precision than conventional buoys. [14] |
| 4363 | Astronomic(Al) Arc | See arc. [14] |
| 4364 | Astronomic(Al) Day | See day. [14] |
| 4365 | Atmospheric Models | Simulation of the atmosphere's behavior by mathematical equations or by physical models. [1] |
| 4366 | Atmospheric Window | The region in the radiation spectrum containing wavelengths between 8.5 and 11 micrometers, which are not absorbed to any great extent by atmospheric gases. In the absence of cloud, terrestrial radiation of this wavelength is lost to space, enabling the cooling of the earth to take place. Other narrower wavebands also do not absorb long-wave radiation, but these are of less importance in this context. [14] |
| 4367 | Barometer: Aneroid | Barometer whose sensitive element comprises one or a series of aneroid capsules. [14] |
| 4368 | Base Height Ration | In photogrammetry, the ratio between the air base and the flight altitude of a stereoscopic pair of photographs. [14] |
| 4369 | Baseline: Straight | Straight baselines are a system of straight lines joining specified or discrete points on the low-water line, usually known as straight baseline turning points. Straight baselines are used in delimitation. [14] |
| 4370 | Bucket Temperature | Temperature of surface sea water trapped and measured in a bucket or similar receptacle. [14] |
| 4371 | Cassini Projection | See projection. [14] |
| 4372 | Channel: Frequency | A continuous portion of the frequency spectrum appropriate for a transmission utilizing a specified class of emission. [14] |
| 4373 | Character Of Light | The distinct character, such as fixed, flashing, or occulting, which is given to each light to avoid confusion with neighbouring ones. [14] |
| 4374 | Chart: Bathymetric | A topographic chart of the bed of a body of water, or a part of it. Generally, bathymetric charts show depths by contour lines and gradient tints. [14] |
| 4375 | Chart: Geophysical | A chart which primarily shows parameters of geophysical nature. [14] |
| 4376 | Chart: Layer Depth | A chart showing the synoptic distribution of layer depths. [14] |
| 4377 | Chart: New Edition | See new edition (of chart). [14] |
| 4378 | Chart: Provisional | A special chart, usually for which there is an urgent need. The chart is compiled from approved source materials and may be drafted for direct reproduction. All charted information is usually combined on the black printing plate and no other colors are shown. [14] |
| 4379 | Circle Of Position | The small circle on the surface of the earth on which an observation shows the observer to be. The expression is most frequently used to indicate the circle of equal altitude. Also called position circle. [14] |
| 4380 | Circle: Horizontal | In a surveying instrument, the graduated circle used for measuring horizontal angles. [14] |
| 4381 | Coastal Refraction | See refraction. [14] |
| 4382 | Colure: Solsticial | The hour circle through the solstices. [14] |
| 4383 | Compacted Ice Edge | A close, clear-cut ice edge compacted by wind or current. It is usually on the windward side of an area of pack ice. [14] |
| 4384 | Compasses: Pair Of | See compass. [14] |
| 4385 | Compensating Coils | The coils placed near a magnetic compass to neutralize the effect of the vessel's degaussing system on the compass. [14] |
| 4386 | Compensation Depth | See depth. [14] |
| 4387 | Compression Ratios | See flattening of the earth. [14] |
| 4388 | Computer: Analogue | A physical device or system which behaves in a manner analogous to some system under study, simulating the processes and producing results which are measured in terms of physical quantities. Often an electrical system. [14] |
| 4389 | Concentration: Ice | See ice. [14] |
| 4390 | Condensation Level | The level above the surface marking the base of a cumuliform cloud. [1] |
| 4391 | Constant Deviation | See deviation. [14] |
| 4392 | Convection: Forced | In the atmosphere, convection caused by mechanical forces, such as those arising from air motion over a rough or sloping surface. [14] |
| 4393 | Coordinates: Polar | A system of coordinates used to describe the position of a point in space with respect to an arbitrarily chosen origin by means of two directions and one distance; i.e., the vectorial angles and radius vector magnitude. [14] |
| 4394 | Coordinates: Space | In photogrammetry the term may refer to any general three-dimensional coordinate system used to define the position of a point in the object space, as distinguished from the image of the same point on a photograph. [14] |
| 4395 | Coordinates: Strip | The coordinates of any point in a strip, whether on the ground or actually an air station, referred to the origin and axes of the air coordinate system of the first overlap. [14] |
| 4396 | Correlate Equation | See equation: correlate. [14] |
| 4397 | Course Over Ground | The direction of the path over the ground actually followed by a vessel. It is normally a somewhat irregular line. This is a misnomer in that courses are directions steered or intended to be steered through the water with respect to a reference meridian. Also called track over ground. [14] |
| 4398 | Current Difference | The difference between the time of slack water or strength of current at a subordinate station and at its reference station. [14] |
| 4399 | Current: Ocean/Sea | A movement of ocean water characterized by regularity, either of a cyclic nature or as a continuous stream flowing along a definable path. [14] |
| 4400 | Current: Permanent | A current which continues with relatively little periodic or seasonal change. [14] |
| 4401 | Current: Turbidity | A highly turbid, relatively dense current carrying large quantities of clay, silt and sand in suspension which flows down a submarine slope through less dense sea water. [14] |
| 4402 | Datum For Sounding | See datum: sounding. [14] |
| 4403 | Declination Circle | See hour circle. [14] |
| 4404 | Deep-Draught Route | A route which is primarily selected for use by ships which, because of their deep draught, may not be able to navigate safely outside such route. [14] |
| 4405 | Depression Contour | See contour. [14] |
| 4406 | Depth: Controlling | The least depth in the approach or channel to an area, such as a port or anchorage, governing the maximum draft of vessels that can enter. [14] |
| 4407 | Dip Of The Horizon | See dip. [14] |
| 4408 | Distance Reduction | See reduction to sea level. [14] |
| 4409 | Distortion: Radial | A lens aberration that is corrected on the photograph by displacing the image along a radial line from the principal point. [14] |
| 4410 | Doppler Navigation | See navigation. [14] |
| 4411 | Draft (Or Draught) | The vertical distance, at any section of a vessel from the surface of the water to the bottom of the keel. When measured at or near the bow, it is referred to as draft forward and when measured at or near the stern as draft aft. The mean draft is the mean of the drafts forward and aft. These drafts are more specifically described as displacement drafts as opposed to navigational drafts which are measured to the lowest appendage to the hull as opposed to the keel. [14] |
| 4412 | Echo(Es): Multiple | In echo sounding, any of the echoes received subsequent to the first one and due to a multiplicity of reflections back and forth between the bottom and surface. These reflections often register on the dial of a usual indicator, or on the fathogram of a graphic recorder, at multiplies of the true depth. Such echoes are sometimes mistaken for the first echo. [14] |
| 4413 | Elevation Of Sight | Also called height of eye. The visibility distances are relevant with the elevation of the observer's sight. When measuring a long distance by optics a line of sight should be maintained over the convex curvature of the earth and all obstacles between the measuring points. [14] |
| 4414 | Equation: Personal | See personal equation. [14] |
| 4415 | Equator: Celestial | The great circle on the celestial sphere whose plane is perpendicular to the axis of the earth. Also called equinoctial. [14] |
| 4416 | Equatorial Tide(S) | See tide. [14] |
| 4417 | Equinoctial Colure | See colure. [14] |
| 4418 | Error: Mean Square | The quantity whose square is equal to the sum of the squares of the individual errors divided by the number of those errors. [14] |
| 4419 | Error: Parallactic | An error caused by personal or instrumental parallax. [14] |
| 4420 | Error: Theoretical | A systematic error arising from natural physical conditions, beyond the control of the observer. Also called external error. [14] |
| 4421 | Existence Doubtful | Of uncertain existence. The expression is used principally on charts to indicate the possible existence of a rock, shoal, etc., the actual existence of which has not been established. Usually shown by the abbreviation 'ed'. [14] |
| 4422 | Exploratory Survey | See survey. [14] |
| 4423 | Eye (Of Hurricane) | A region in the center of a hurricane (tropical cyclone) where the winds are light and skies are clear to partly cloudy. [1] |
| 4424 | Floe (Or Ice Floe) | A piece of sea ice other than fast ice. Floes over 10 km across are described as vast; those between 1 and 10 km across as big; those between 200 and 1,000 m across as medium; those between 10 and 200 m across as small. Floes less than 10 m across are called ice cakes. [14] |
| 4425 | Fog Detector Light | A light used to automatically determine conditions of visibility which warrant the turning on or off of a sound signal. [14] |
| 4426 | Formation Sounding | See sounding. [14] |
| 4427 | Frequency: Natural | The lowest resonant frequency of a body or system. [14] |
| 4428 | Gas Chromatography | An analysis method used to determine dissolved oxygen and nitrogen content of sea water. [14] |
| 4429 | Geodesy: Satellite | The discipline which employs observations of an earth satellite to extract geodetic information. [14] |
| 4430 | Geodetic Levelling | See levelling. [14] |
| 4431 | Geology: Submarine | A field of study which applies the science of geology to the earth beneath the sea. [14] |
| 4432 | Gravimetric Survey | See survey. [14] |
| 4433 | Gravity: Centre Of | A point at which the mass of the entire body may be regarded as being concentrated. [14] |
| 4434 | Great Circle Chart | See chart: gnomonic. [14] |
| 4435 | Great Tropic Range | See range. [14] |
| 4436 | Growing Degree-Day | A form of the degree-day used as a guide for crop planting and for estimating crop maturity dates. [1] |
| 4437 | Heating Degree-Day | A form of the degree-day used as an index for fuel consumption. [1] |
| 4438 | Heave Compensation | The removal of the effect of wave motion from the recorded seabed profile. [14] |
| 4439 | High Water: Double | A high water consisting of two maxima of nearly the same height separated by a relatively small depression. See also tide: double. [14] |
| 4440 | Horizon Photograph | In aerial photography, a photograph of the horizon, taken simultaneously with a vertical photograph and used to determine the relative tilt between adjacent vertical photographs. [14] |
| 4441 | Horizon: Celestial | That circle of the celestial sphere, formed by the intersection of the celestial sphere and a plane through the center of the earth, and perpendicular to the zenith-nadir line. Also called rational horizon. [14] |
| 4442 | Horizontal Coplane | See coplane: basal. [14] |
| 4443 | Hydrographic Chart | See chart: nautical. [14] |
| 4444 | Hydrographic Datum | See datum: chart. [14] |
| 4445 | Hydroplastic Corer | See corer. [14] |
| 4446 | Indirect Levelling | See levelling. [14] |
| 4447 | Instrument Shelter | A boxlike (often wooden) structure designed to protect weather instruments from direct sunshine and precipitation. [1] |
| 4448 | Inverting Eyepiece | See eyepiece: erecting. [14] |
| 4449 | Isometric Latitude | See latitude. [14] |
| 4450 | Latitude: Magnetic | The angle whose tangent is one half the tangent of the magnetic inclination or dip. [14] |
| 4451 | Layer Of No Motion | A layer, assumed to be at rest at some depth in the ocean. [14] |
| 4452 | Librations Of Moon | Motions of the moon due to which certain margins round the moon's limb occasionally pass out of view while a corresponding margin on the other side comes into view. The librations enable 59 per cent of the moon's surface to be seen at one time or another. [14] |
| 4453 | Light(S): Boundary | Lights marking the boundary of a landing area. [14] |
| 4454 | Light(S): Vertical | Two or more lights disposed vertically to give a different character or appearance. [14] |
| 4455 | Light: Alternating | A signal light that shows, in any given direction, two or more colors in a regularly repeated sequence with a regular periodicity. [14] |
| 4456 | Light: Group Quick | A light in which flashes are combined in groups including the same number of quick flashes (repetition rate : 50-79 per minute) and in which groups are repeated at regular intervals. [14] |
| 4457 | Light: Obstruction | Light indicating the presence of an obstruction. [14] |
| 4458 | Lighted Sound Buoy | See buoy. [14] |
| 4459 | Longwave Radiation | A term most often used to describe the infrared energy emitted by the earth and the atmosphere. [1] |
| 4460 | Low Frequency (Lf) | See frequency: radio. [14] |
| 4461 | Low Velocity Layer | Any layer in which the velocity of compressional wave propagation is lower than in the adjacent layers. Such a layer can act as an efficient channel for the propagation of elastic waves for great distances. [14] |
| 4462 | Low-Tide Elevation | A naturally formed area of land which is surrounded by and above water at low tide, but submerged at high tide. [14] |
| 4463 | Magnetic Induction | The act or process by which material becomes magnetized when placed in a magnetic field. [14] |
| 4464 | Magnetic Variation | See variation. [14] |
| 4465 | Magnetism: Induced | Magnetism acquired by a piece of magnetic material while it is in a magnetic field. [14] |
| 4466 | Map: Hemispherical | A map of one half of the earth's surface, bounded by the equator, or by meridians. [14] |
| 4467 | Maregraph Plongeur | An instrument for measuring changes in sea level by automatically recording changes in pressure at sea bottom. Two bourdon tubes are open to pressure and a mechanism records the resultant movements of their free ends. [14] |
| 4468 | Marker Radiobeacon | See marker beacon. [14] |
| 4469 | Mathematical Model | A mathematical representation, usually of a process, device, or concept, which permits mathematical manipulation of variables as a means to determine how the process, device, or concept would behave in various situations as e.g. The application of a specific simulation. [14] |
| 4470 | Meridian Telescope | See telescope. [14] |
| 4471 | Meridian: Geodetic | A line on a spheroid which has the same geodetic longitude at every point. [14] |
| 4472 | Meridian: Magnetic | A line of horizontal magnetic force of the earth. The vertical plane in which a freely suspended, symmetrically magnetized needle, influenced by no transient, artificial, magnetic disturbance, will come to rest. [14] |
| 4473 | Meridian: Standard | The meridian used for reckoning standard time. A meridian of a map projection, along which the scale is as stated. [14] |
| 4474 | Micrometer: Run Of | See error of run. [14] |
| 4475 | Middle Ground Buoy | A buoy marking a shoal with channels on both sides. See bifurcation buoy, junction buoy. [14] |
| 4476 | Minor Control Plot | See radial triangulation. [14] |
| 4477 | Moat (Or Sea Moat) | an annular depression that may not be continuous, located at the base of many seamounts, oceanic islands and other isolated elevations. [14] |
| 4478 | Month: Anomalistic | The interval of time between two successive passages of the moon in its orbit through perigee. The length of the anomalistic month is 27.55455 mean solar days. [14] |
| 4479 | Mosaic: Controlled | A mosaic oriented and scaled to horizontal ground control; usually assembled from rectified photographs. See also orthophoto mosaic, uncontrolled mosaic. [14] |
| 4480 | Navigation: Aerial | See navigation: air. [14] |
| 4481 | Navigation: Marine | Navigation of watercraft. [14] |
| 4482 | Navigational Stars | Selected bright stars whose positions are precisely tabulated in nautical almanacs for navigational purposes. [14] |
| 4483 | Negative Engraving | A chart reproduction process in which the compilation manuscript, or other data, is photographed onto a plastic or glass negative. The art of creating facsimile images on a reproduction media by utilizing hand engraving techniques. [14] |
| 4484 | Noctilucent Clouds | Wavy, thin, bluish-white clouds that are best seen at twilight in polar latitudes. They form at altitudes about 80 to 90 km above the surface. [1] |
| 4485 | Nodal Point: Front | See nodal point. [14] |
| 4486 | Nonharmonic Method | In tide prediction, an approximate method based on the principle that 'the tide follows the moon'. It makes use of the close relationship that exists between the time of tide at most places and the moon's meridian transit. [14] |
| 4487 | Notice To Mariners | A periodical or casual notice issued by hydrographic offices, or other competent authorities, regarding changes in aids to navigation, dangers to navigation, important new soundings, and, in general, all such information as affects nautical charts, sailing directions, light lists and other nautical publications. [14] |
| 4488 | Oceanographic Cast | See cast. [14] |
| 4489 | Offset Lithography | A method of printing in which an image is transferred from a printing plate on to a rubber-surfaced blanket and thence on the paper. The image on the plate is a right reading image. [14] |
| 4490 | Orientation: Inner | See orientation: interior. [14] |
| 4491 | Orientation: Outer | See orientation: exterior. [14] |
| 4492 | Parallax: Personal | See parallax: instrumental. [14] |
| 4493 | Parallax: Vertical | See parallax: y-. [14] |
| 4494 | Parallel: Geodetic | A line on the spheroid which has the same geodetic latitude at every point. A geodetic parallel, other than the equator, is not a geodetic line. In form, it is a small circle whose plane is parallel with the plane of the geodetic equator. [14] |
| 4495 | Parallel: Standard | A parallel of latitude which is used as a control in the computation of a map projection. For a tangent cone, this is the parallel of tangency. For a secant cone, the two parallels of intersection are the standards. [14] |
| 4496 | Paraselenic Circle | Photometeor of the halo family, analogous to the parhelic circle, the luminary being the moon. [14] |
| 4497 | Particulate Matter | Solid particles or liquid droplets that are small enough to remain suspended in the air. Also called aerosols. [1] |
| 4498 | Photocontrol Point | See control point. [14] |
| 4499 | Photograph: Aerial | Any photograph taken from the air. Sometimes called air photograph. [14] |
| 4500 | Photograph: Ground | See photograph: terrestrial. [14] |
| 4501 | Platform: Offshore | A permanent offshore structure, either fixed or floating, used in the production of oil or natural gas. [14] |
| 4502 | Polar Front Theory | A theory developed by a group of Scandinavian meteorologists that explains the formation, development, and overall life history of cyclonic storms that form along the polar front. [1] |
| 4503 | Polaris Correction | A correction to be applied to the observed altitude of Polaris to obtain the latitude. [14] |
| 4504 | Polarization Error | See error. [14] |
| 4505 | Position: Adjusted | An adjusted value of the coordinate position of a point on the earth. [14] |
| 4506 | Position: Apparent | In astronomy, the position of a celestial body reduced to the center of the earth. It differs from the position in which the object is observed as to the effects of refraction, diurnal aberration, and diurnal parallax. [14] |
| 4507 | Position: Geodetic | A point on the earth, the coordinates of which have been determined by triangulation from an initial station whose location has been established as a result of astronomical observations. The coor-dinates of such a position depend upon the reference spheroid used. [14] |
| 4508 | Position: Relative | A point defined with reference to another position, either fixed or moving. [14] |
| 4509 | Precautionary Area | A routing measure comprising an area within defined limits where ships must navigate with particular caution and within which the direction of traffic flow may be recommended. [14] |
| 4510 | Principal Distance | The perpendicular distance from the internal perspective center to the plane of a particular finished negative or print. This distance is equal to the calibrated focal length corrected for both the enlargement or reduction ratio of the film or paper shrinkage or expansion and maintains the same perspective angles at the internal perspective center to points on the finished negative or print, as existing in the taking camera at the moment of exposure. [14] |
| 4511 | Principal Meridian | See meridian. [14] |
| 4512 | Projection: Skewed | Any standard projection used in map or chart construction, which does not conform to a general north-south format with relation to the neat lines of the map or chart. [14] |
| 4513 | Pulse (Or Impulse) | A variation of quantity whose value is normally constant (often zero), the variation being characterized by a rise and a decay. A common example is a very short burst of electromagnetic energy. See wave: continuous. [14] |
| 4514 | Range Of Mountains | See mountain range. [14] |
| 4515 | Rayleigh Criterion | Used in tidal analysis. Only those harmonic constituents which are separated by at least a complete period from their neighbouring constituents over the length of data available should be included in the harmonic analysis of a given time series. [14] |
| 4516 | Recommended Course | See track: recommended. [14] |
| 4517 | Reconnaissance Map | See map. [14] |
| 4518 | Rectified Altitude | See altitude: apparent. [14] |
| 4519 | Rectilinear Stream | See current: reversing. [14] |
| 4520 | Reduction Of Tides | The processing of observed tidal data to obtain mean values of tidal constants. [14] |
| 4521 | Residual Deviation | See deviation. [14] |
| 4522 | Residual Magnetism | See magnetism. [14] |
| 4523 | Rhumb Line Sailing | See sailing. [14] |
| 4524 | Route: Recommended | A route of undefined width, for the convenience of ships in transit, which is often marked by centerline buoys. [14] |
| 4525 | Rudite (Or Rudyte) | Rock or sediment deposits composed of grains larger than 2 millimeters. [14] |
| 4526 | Sailing Directions | Information published in book form describing coasts, waters, channels, harbor facilities, etc., for use by mariners. [14] |
| 4527 | Sailing: Composite | A modification of great-circle sailing used when it is desired to limit the highest latitude. [14] |
| 4528 | Sailing: Spherical | Any of the sailings which consider the spherical or spheroidal shape of the earth. [14] |
| 4529 | Satellite Sounding | Sounding effected by means of instruments placed on board an artificial satellite. [14] |
| 4530 | Scale: Logarithmic | A scale graduated in the logarithms of uniformly-spaced consecutive numbers. [14] |
| 4531 | Sea-Level Pressure | The atmospheric pressure at mean sea level. [1] |
| 4532 | Seamount (Or Peak) | An isolated or comparatively isolated elevation rising 1 000 meters or more from the sea floor and of limited extent across the summit. [14] |
| 4533 | Second Nodal Point | See nodal point. [14] |
| 4534 | Seismic Reflection | The study of the shallower internal structure of the earth by generating acoustic waves and registering their reflection from subsurface layers. [14] |
| 4535 | Seismic Refraction | The study of the shallower internal structure of the earth by generating acoustic waves and registering their return at increasing distances from the acoustic source, thus detecting waves that have been transmitted along deeper layers of greater elasticity and rigidity. [14] |
| 4536 | Sextant Adjustment | The process of checking the accuracy of a sextant and removing or reducing its error. [14] |
| 4537 | Sextant: Surveying | See sextant: sounding. [14] |
| 4538 | Small Tropic Range | See range. [14] |
| 4539 | Solsticial Tide(S) | See tide. [14] |
| 4540 | Sounding Apparatus | Any apparatus designed for use in measuring the depth of water. [14] |
| 4541 | Sounding Selection | 1. Water depths numerically displayed on a chart. 2. The process of choosing individual water depths from a hydrographic survey in the compilation of a chart. [14] |
| 4542 | Sounding(S): Minus | (US Terminology). Soundings that reduce to height above the sounding datum (plane of reference) when corrected for height of tide. Minus soundings are shown on the smooth sheet preceded by a minus sign. [14] |
| 4543 | Sounding: Acoustic | See echo sounding. [14] |
| 4544 | Sounding: Doubtful | A depth shown on a chart over a shoal, a rock, etc., that may be less than that indicated. [14] |
| 4545 | Squares: Method Of | A method of transferring one survey to another of different scale. Also called squaring down or squaring up depending on whether the scale is being decreased or increased. [14] |
| 4546 | Stabilizer: Marine | A device installed on ships to reduce rolling. [14] |
| 4547 | State Of Sea Scale | Numerical scale of average wave height in which the numbers increase with the wave height. [14] |
| 4548 | Station: Eccentric | See eccentric station. [14] |
| 4549 | Station: Reference | A place where tide or tidal current constants have been determined from observations, and which is used as a standard for the comparison of simultaneous observations at a subordinate station. It is also a place for which independent daily predictions are given in the tide or tidal current tables, from which corresponding predictions are obtained for other locations by means of differences or factors. Also called standard station and standard port (British terminology). [14] |
| 4550 | Station: Resection | A station located by resection methods. [14] |
| 4551 | Station: Satellite | See eccentric station. [14] |
| 4552 | Station: Secondary | See station: supplementary. [14] |
| 4553 | Stereoscopic Model | See stereoscopic image. [14] |
| 4554 | Straight-Line Wind | Strong winds created by a thunderstorm's downdraft that flows outward, away from the storm in a straight line, more or less parallel to the ground. [1] |
| 4555 | Strength Of Figure | In geodesy, the comparative precision of computed lengths in a triangulation net as determined by the size of the angles, the number of conditions to be satisfied, and the distribution of bases and points of fixed position. [14] |
| 4556 | Sub-Sea Completion | See well: production. [14] |
| 4557 | Subsidiary Station | See station. [14] |
| 4558 | Subsurface Current | See current. [14] |
| 4559 | Superior Planet(S) | See planet(s): superior. [14] |
| 4560 | Superjacent Waters | The waters lying immediately above the sea-bed or deep ocean floor up to the surface. [14] |
| 4561 | Surface Navigation | See navigation. [14] |
| 4562 | Surface Reflection | The return of sound rays to depth after striking the sea surface. [14] |
| 4563 | Surveyor'S Compass | See compass. [14] |
| 4564 | System Development | The development of a program system comprising analysis, design, programming, testing, and implementation. [14] |
| 4565 | Telescopic Alidade | See alidade. [14] |
| 4566 | Terrestrial Camera | See camera. [14] |
| 4567 | Territorial Waters | See territorial sea. [14] |
| 4568 | Tide(S): Predicted | The expected times and heights of the tide as given in the tide tables in advance of their occurrence. [14] |
| 4569 | Tide(S): Secondary | Those additional tides higher low waters and lower high waters that occur twice a month (when the moon is over the equator) in a general pattern of diurnal tides. [14] |
| 4570 | Tide: Astronomical | Tide due to the attraction of the sun and moon, in contrast to a meteorological tide, caused by meterological conditions. Equilibrium tide. [14] |
| 4571 | Time: Geologic(Al) | The division into a number of great eras, each represented by a group of rocks. [14] |
| 4572 | Transit Theodolite | See transit. [14] |
| 4573 | Vertical Clearance | The minimum vertical space available for passage. [14] |
| 4574 | Very Open Pack Ice | Sea ice the concentration of which ranges between 1/10ths 3/10ths. [14] |
| 4575 | Visibility: Flight | The visibility forward from the cockpit of an aircraft in flight. [14] |
| 4576 | Warning: Hurricane | Meteorological message intended to warn those concerned of the occurrence or expected occurrence of a wind of beaufort force 12 over a specified area. Tropical cyclone warning relating to a hurricane. [14] |
| 4577 | Water Specimen Cup | See water bottle. [14] |
| 4578 | Wave: Longitudinal | A wave in which the direction of displacement of each particle in the medium is perpendicular to the wave front. [14] |
| 4579 | Wellhead: Offshore | See well: offshore. [14] |
| 4580 | Wire And Bar Sweep | See bar sweeping and wire drag sweep. [14] |
| 4581 | Acoustic Navigation | See navigation: sonic. [14] |
| 4582 | Altitude Difference | See intercept. [14] |
| 4583 | Altitude: Rectified | See altitude: apparent. [14] |
| 4584 | Aperture Of Antenna | The diameter of a reflector antenna, usually expressed in units of wavelength. [14] |
| 4585 | Apparent Precession | Apparent change in the direction of the axis of rotation of a spinning body, as a gyroscope, due to the rotation of the earth. [14] |
| 4586 | Archipelagic Waters | The waters enclosed by archipelagic baselines. [14] |
| 4587 | Astronomic(Al) Tide | See tide. [14] |
| 4588 | Astronomic(Al) Time | See time. [14] |
| 4589 | Astronomic(Al) Year | See year: tropical. [14] |
| 4590 | Astronomy: Geodetic | Astronomy as applied to geodesy. [14] |
| 4591 | Axis Of Collimation | See collimation axis. [14] |
| 4592 | Axis Of Perspective | See axis of homology. [14] |
| 4593 | Barometric Gradient | See pressure gradient. [14] |
| 4594 | Barometric Pressure | See pressure: barometric. [14] |
| 4595 | Base Line Extension | In radiolocation, the extension of the base line beyond the transmitters. [14] |
| 4596 | Base Tape (Or Wire) | A tape or wire of metal or alloy, so designed and graduated that it is suitable for measuring the lengths of bases. See also tape: invar, tape: steel and wire: invar. [14] |
| 4597 | Beacon: Transponder | See transponder beacon. [14] |
| 4598 | Bearing: Reciprocal | A bearing differing by 180° from a given bearing. [14] |
| 4599 | Beaufort Wind Scale | A numerical scale for indicating wind speed, devised by admiral sir francis beaufort in 1805. Beaufort numbers (or forces) range from force 0 (calm) to force 12 (hurricane). [14] |
| 4600 | Buoy: Lighted Sound | A light buoy provided with a sound signal. [14] |
| 4601 | Buoyancy: Centre Of | Centre of gravity of liquid displaced by a floating body. [14] |
| 4602 | Buoy-Control Method | A system of accurately located buoys on which three-point fixes could be observed, or to which distances could be measured by radio acoustic methods, for extending hydrographic surveys beyond the visibility of shore control. [14] |
| 4603 | Camera: Terrestrial | A camera designed for use on the ground. See phototheodolite. [14] |
| 4604 | Cardanic Suspension | See gimbals. [14] |
| 4605 | Cay (Also Kay, Key) | A low, flat island of sand, coral, etc. Awash or drying at low water; a term originally applied to the coral islets around the coast and islands of Caribbean sea. [14] |
| 4606 | Cesium Magnetometer | See magnetometer. [14] |
| 4607 | Chart: Aeronautical | A representation of a portion of the earth, its culture and relief, specifically designed to meet the requirements of air navigation. [14] |
| 4608 | Chart: Great Circle | See chart: gnomonic. [14] |
| 4609 | Chart: Hydrographic | See chart: nautical. [14] |
| 4610 | Chronometric Method | A former method of determining longitude by transporting chronometers between stations whose difference of longitude was to be determined. [14] |
| 4611 | Circle: Fundamental | See primary great circle. [14] |
| 4612 | Closing The Horizon | See horizon. [14] |
| 4613 | Coast Guard Station | a station at which a visual/radio/radar marine watch is kept either continuously or at certain times only. [14] |
| 4614 | Colour Of Sea Water | See sea water. [14] |
| 4615 | Colure: Equinoctial | The hour circle through the equinoxes. [14] |
| 4616 | Compass Calibration | See swinging ship. [14] |
| 4617 | Compass: Gyroscopic | A compass having one or more gyroscopes as the directive element, and tending to indicate true north. Also called gyro compass. [14] |
| 4618 | Compass: Surveyor'S | An instrument for determining a magnetic bearing of a line of sight by the use of a sighting device, a graduated horizontal circle and a pivoted needle. [14] |
| 4619 | Compilation Diagram | See source diagram. [14] |
| 4620 | Conical Projections | The map projections produced by projecting the geographic meridians and parallels onto a cone which is tangent to or intersects the surface of a sphere, and then developing the cone into a plane. [14] |
| 4621 | Contour: Depression | A closed contour inside of which the ground is at lower elevation than outside. See also form line. [14] |
| 4622 | Control: Horizontal | Control that is determined in horizontal position. The position may be referred to any recognized geographic or plane coordinate system. [14] |
| 4623 | Corer: Hydroplastic | A deep sea coring device, developed at the US Naval oceanographic office, to obtain 3 1/2-inch diameter cores up to 12 feet in length. The barrel is constructed of high-impact grade polyvinyl chloride plastic without an inner liner. Also called polyvinyl corer. [14] |
| 4624 | Correction(S): Tape | See tape correction(s). [14] |
| 4625 | Course: Recommended | See track: recommended. [14] |
| 4626 | Current: Subsurface | A current usually flowing below the thermocline generally at slower speeds and frequently in a different direction from the currents near the surface. [14] |
| 4627 | Day: Apparent Solar | See day: solar. [14] |
| 4628 | Delambre'S Spheroid | See reference spheroid. [14] |
| 4629 | Departure: Point Of | The point from which the initial course to reach the point of destination begins. [14] |
| 4630 | Depth: Compensation | The depth at which the light intensity is just sufficient to bring about a balance between the oxygen produced by algae through photosynthesis and that consumed by them through respiration. [14] |
| 4631 | Depth: Thermometric | The depth, in meters, at which paired protected and unprotected thermometers attached to a nansen bottle are reversed. The difference between the corrected readings of the 2 thermometers represents the effect of the hydrostatic pressure at the depth of reversal. This depth may then be determined by formula or from a depth anomaly graph. Depths obtained by this means are of greatest value when a wire angle occurs. [14] |
| 4632 | Detection Threshold | The lowest or highest level of a parameter above or below which sensing equipment can detect the parameter. [14] |
| 4633 | Deviation: Constant | Deviation which is the same on any heading, which may result from certain arrangements of asymmetrical horizontal soft iron. [14] |
| 4634 | Deviation: Magnetic | The angle between the compass needle and the magnetic meridian, expressed in degrees east or west of magnetic meridian. Also called deviation. [14] |
| 4635 | Deviation: Residual | Deviation of a magnetic compass after compensation. [14] |
| 4636 | Deviation: Standard | See error: standard. [14] |
| 4637 | Directional Antenna | See antenna. [14] |
| 4638 | Discontinuity Layer | See thermocline. [14] |
| 4639 | Displacement Drafts | See draft. [14] |
| 4640 | Distortion: Angular | In cartography, distortion in a projection because of non-conformality. See conformality. [14] |
| 4641 | Dynamic Positioning | Manoeuvring of a vessel to keep a position relative to a seabed feature; normally underwater acoustic position fixing systems are used for this purpose. [14] |
| 4642 | Eccentric Reduction | In triangulation, the correction which must be applied to a direction observed by an instrument with either the instrument or signal, or both, eccentric, to reduce the observed value to what it would have been if there had been no eccentricity. [14] |
| 4643 | Electromagnetic Log | See log. [14] |
| 4644 | Elevation: Angle Of | See angle of elevation. [14] |
| 4645 | Epact (Of The Year) | The age of the moon at 00 hour on january 1. [14] |
| 4646 | Equation: Condition | An equation which expresses exactly certain relationships that must exist among related quantities, which are not independent of one another, exist a priori, and are separate from relationships demanded by observation. [14] |
| 4647 | Equation: Correlate | An equation derived from an observation or condition equation, using undetermined multipliers, and expressing the condition that the sum of the squares of the residual errors resulting from the application of these multipliers to the observation or condition equations shall be a minimum. [14] |
| 4648 | Error Of Graduation | Inaccuracy in the graduations of the scale of an instrument. Also called graduation error. [14] |
| 4649 | Eyepiece Micrometer | See micrometer: ocular. [14] |
| 4650 | Eyewall Replacement | A situation within a hurricane (tropical cyclone) where the storm's original eyewall dissipates and a new eyewall forms outward, farther away from the center of the storm. [1] |
| 4651 | Fish Trap (Or Weir) | A structure for catching fish. See also tunny net. [14] |
| 4652 | Flare Triangulation | See triangulation. [14] |
| 4653 | Floating Breakwater | A contrivance consisting of a series of square frames of timber connected by mooring chains or cables attached to anchors or stone blocks in such a manner as to form a basin within which vessels riding to anchor may be protected from the violence of the waves. [14] |
| 4654 | Focal-Plane Shutter | See shutter. [14] |
| 4655 | Frequency: Low (Lf) | See frequency: radio. [14] |
| 4656 | Frequency: Resonant | Any frequency at which a body or system vibrates more readily. [14] |
| 4657 | Frost (Or Freezing) | Lowering of air temperature to a value equal to or less than the freezing point of water (0°c). [14] |
| 4658 | Galton'S Sun Signal | See heliostat. [14] |
| 4659 | Geocentric Latitude | See latitude. [14] |
| 4660 | Geodetic Connection | See connection. [14] |
| 4661 | Geographic(Al) Pole | See pole. [14] |
| 4662 | Geologic(Al) Survey | See survey. [14] |
| 4663 | Geostrophic Current | A current in which the balance in the horizontal components of the equations of motion is between the horizontal pressure gradient and the Coriolis force. The vertical component is in hydrostatic balance and the pressure increases with depth in proportion to the mass of water above. If pressure is mapped on a level surface (geopotential), then geostrophic flow is parallel to the isobars, with high pressure to the right (left) of the flow in the Northern (Southern) Hemisphere. For the geostrophic balance to hold, the flow must be steady, very weak, large-scale, and friction-free. [3] |
| 4664 | Gnomonic Projection | See projection. [14] |
| 4665 | Great Diurnal Range | See range: diurnal. [14] |
| 4666 | Greatest Elongation | See elongation. [14] |
| 4667 | Grid Magnetic Angle | See variation: grid. [14] |
| 4668 | Halo (Solar, Lunar) | Group of optical phenomena, in the form of rings, arcs, pillars or bright spots, produced by the refraction or reflection of light by ice crystals suspended in the atmosphere (cirriform clouds, ice fog, etc.). [14] |
| 4669 | Harbour (Or Harbor) | A natural or artificially improved body of water providing protection for vessels, and generally anchorage and docking facilities. See also port. [14] |
| 4670 | Harmonic Prediction | In tidal terminology, the method of predicting tides and tidal currents by combining the harmonic constituents into a single curve. The work was usually done mechanically by a machine designed for this purpose, called a tide predicting machine; nowadays the work is done by computers. [14] |
| 4671 | Helium Magnetometer | See magnetometer. [14] |
| 4672 | High Frequency (Hf) | See frequency: radio. [14] |
| 4673 | Horizon: Artificial | A device for indicating the horizontal, as a bubble, gyroscope, pendulum, or the flat reflecting surface of a liquid. [14] |
| 4674 | Horizon: Dip Of The | See dip. [14] |
| 4675 | Humidity Of The Air | Water vapor content of the air. [14] |
| 4676 | Hydrographic Circle | See circle. [14] |
| 4677 | Hydrophone Streamer | A chain of separate receivers for seismic sound sources towed by a ship. The streamer contains many individual hydrophone elements and is divided electronically into a number of discrete sections or channels. [14] |
| 4678 | Incidence: Angle Of | See angle of incidence. [14] |
| 4679 | Index Of Refraction | See refraction: index of. [14] |
| 4680 | Inertia: Gyroscopic | See gyroscopic inertia. [14] |
| 4681 | Inertial Navigation | See navigation. [14] |
| 4682 | Inferior Planet (S) | See planet (s): inferior. [14] |
| 4683 | Intensity: Magnetic | See magnetic field intensity. [14] |
| 4684 | Intercardinal Point | Any of the four directions midway between the cardinal points: north-east, north-west, south-east, south-west. [14] |
| 4685 | Interglacial Period | A time interval of relatively mild climate during the ice age when continental ice sheets were absent or limited in extent to greenland and the antarctic. [1] |
| 4686 | Latitude: Celestial | Angular distance north or south of the ecliptic; the arc of a circle of latitude between the ecliptic and a point on the celestial sphere, measured northward or southward from the ecliptic through 90°, and labelled n or s to indicate the direction of measurement. Also called ecliptic latitude. [14] |
| 4687 | Latitude: Geometric | See latitude: parametric. [14] |
| 4688 | Latitude: Isometric | An auxiliary latitude used in the conformal mapping of the spheroid on a sphere. [14] |
| 4689 | Levelling: Geodetic | Spirit levelling of a high order of accuracy, usually extended over large areas, to furnish accurate vertical control as a basis for the control in the vertical dimension for all surveying and mapping operations. [14] |
| 4690 | Levelling: Indirect | The determination of differences of elevation from (a) vertical angles and horizontal distances, as in trigonometric levelling; (b) comparative elevations derived from values of atmospheric pressure determined with a barometer, as in barometric levelling; and (c) elevations derived from values of the boiling point of water determined with a hypsometer, as in thermometric levelling. [14] |
| 4691 | Life Saving Station | a place where equipment for saving life at sea is maintained. Also called rescue station. [14] |
| 4692 | Light: Intermittent | See light: rhythmic. [14] |
| 4693 | Local Apparent Noon | See noon. [14] |
| 4694 | Local Sidereal Time | See time. [14] |
| 4695 | Long-Range Forecast | Generally used to describe a weather forecast that extends beyond about 8.5 days into the future. [1] |
| 4696 | Magnetism: Residual | Magnetism which remains after removal of the magnetizing force. [14] |
| 4697 | Magnetometer Survey | See survey. [14] |
| 4698 | Main Scheme Station | See station. [14] |
| 4699 | Map: Reconnaissance | The plotted result of a reconnaissance survey. [14] |
| 4700 | Master Gyro Compass | See compass. [14] |
| 4701 | Mature Thunderstorm | The second stage in the three-stage cycle of an ordinary thunderstorm. This mature stage is characterized by heavy showers, lightning, thunder, and violent vertical motions inside cumulonimbus clouds. [1] |
| 4702 | Maximum Thermometer | A thermometer with a small constriction just above the bulb. It is designed to measure the maximum air temperature. [1] |
| 4703 | Maximum Wave Height | Estimated highest wave height from the significant wave height calculated. [-] |
| 4704 | Mean Rise (Of Tide) | The height of mean high water above the chart datum. [14] |
| 4705 | Meridian: Celestial | A great circle of the celestial sphere through the celestial poles and the zenith. The expression usually refers to the upper branch. [14] |
| 4706 | Meridian: Greenwich | The astronomical meridian through the center of the transit instrument of the observatory of Greenwich, England, serving as the reference for Greenwich time, in contrast with local meridian. [14] |
| 4707 | Meridian: Principal | (US Terminology). A true north-south line (a meridian) extending both north and south of the initial point in the rectangular system of surveys. Together with the base line they constitute the axes of a system and the initial point the origin of that system. See principal line. [14] |
| 4708 | Meridian-Arc Method | A method of determining the dimensions of the ellipsoid by measuring (by triangulation) the linear distances between three points on a meridian and the angular distances between them from observed differences in their astronomical latitudes. [14] |
| 4709 | Meridional Distance | The difference of latitude between two points on a map projection's graticule converted to suitable linear units. [14] |
| 4710 | Meteorological Tide | See tide. [14] |
| 4711 | Milankovitch Theory | A theory proposed by Milutin Milankovitch in the 1930s suggesting that changes in the earth's orbit were responsible for variations in solar energy reaching the earth's surface and climatic changes. [1] |
| 4712 | Minimum Thermometer | A thermometer designed to measure the minimum air temperature during a desired time period. [1] |
| 4713 | Monsoon Wind System | A wind system that reverses direction between winter and summer. Usually the wind blows from land to sea in winter and from sea to land in summer. [1] |
| 4714 | Most Probable Value | That value of a quantity which is mathematically determined from a series of observations and is more probably free of the effects of blunders and errors than any other value that might stem from the same series of observations. [14] |
| 4715 | Multiple Tide Staff | See tide staff. [14] |
| 4716 | Navigation: Doppler | Navigation using equipment employing doppler shift measurement techniques with respect to transmitted and reflected signals to automatically compute drift angle and ground speed. Drift angle and ground speed are used in dead reckoning performed either manually or, as in many installations, by dead reckoning computers. In either case, craft heading is a necessary input. [14] |
| 4717 | Navigation: Surface | Navigation of a craft on the surface of the earth. The expression is used particularly with reference to navigation of vessels on the surface of water. See navigation: land and navigation: underwater. [14] |
| 4718 | Navigational Drafts | See draft. [14] |
| 4719 | Oceanic Circulation | A unique interrelated system of major ocean currents within a large area; usually a closed circular pattern such as in the north Atlantic, Mediterranean, etc. [14] |
| 4720 | Orange Peel Sampler | A bottom sediment sampling device capable of obtaining as much as 1/2 cubic foot of sample from the ocean floor. Named for its likeness to an orange that has its peel quartered. [14] |
| 4721 | Parallax Correction | A correction due to parallax, particularly that sextant altitude correction due to the difference between the apparent direction from a point on the surface of the earth to a celestial body and the apparent direction from the center of the earth to the same body. [14] |
| 4722 | Parallax Difference | In photogrammetry, the difference in the absolute stereoscopic parallaxes of two points imaged on a pair of photographs. Customarily used in determination of the difference in elevations of objects. [14] |
| 4723 | Parallax Inequality | The variation in the range of tide or in the speed of tidal currents due to the continual change in the distance of the moon from the earth. [14] |
| 4724 | Parallel: Celestial | See parallel of declination. [14] |
| 4725 | Parallel: Isometric | In photogrammetry, the intersecting line between the plane of a photograph and a horizontal plane having an equal perpendicular distance from the same perspective center. [14] |
| 4726 | Parallel: Principal | See parallel: photograph. [14] |
| 4727 | Personal Correction | The correction due to personal error. [14] |
| 4728 | Photoelectric Pilot | A device for automatic steering in conjunction with the magnetic compass. Its pinnacle unit, or directive element, consists of a high-grade magnetic compass of special construction, a simple light system, and a photoelectric cell, so arranged that the slightest deviation of the vessel from its course is detected and relayed to the steering engine unit. [14] |
| 4729 | Photograph: Oblique | A photograph taken with the camera axis intentionally directed between the horizontal and the vertical. [14] |
| 4730 | Photography: Aerial | The art, science, or process of taking aerial photographs. [14] |
| 4731 | Planet(S): Inferior | The planets with orbits smaller than that of the earth: mercury and venus. [14] |
| 4732 | Planet(S): Superior | The planets with orbits larger than that of the earth: mars, jupiter, saturn, uranus, neptune, and pluto. [14] |
| 4733 | Position: Estimated | The most probable position of a craft determined from incomplete data or data of questionable accuracy. Such a position might be determined by applying a correction to the dead reckoning position. [14] |
| 4734 | Precision Ephemeris | The ephemeris which describe the orbit of a navigational satellite precisely. They are of higher precision than the broadcast ephemeris but not available in real time. [14] |
| 4735 | Pressure Hydrophone | A hydrophone in which the electric output substantially corresponds to the instantaneous sound pressure of the impressed sound wave. [14] |
| 4736 | Prismatic Astrolabe | See astrolabe. [14] |
| 4737 | Production Platform | A term used to indicate a permanent offshore structure equipped to control the flow of oil or gas. For charting purposes, the use of the term is extended to include all permanent platforms associa-ted with oil or gas production, e.g., field terminal, drilling and accommodation platforms, and "booster" platforms located at intervals along some pipelines. It does not include entirely submarine structures. See also platform. [14] |
| 4738 | Projection: Cassini | A conventional projection constructed by computing the lengths of arcs along a selected geographic meridian and along a great circle perpendicular to that meridian, and plotting these as rectangular coordinates on a plane. [14] |
| 4739 | Radar Guided Tracks | Recommended tracks along which ships can be guided by coastal radar stations in the event of bad visibility. [14] |
| 4740 | Radiation Inversion | An increase in temperature with height due to radiational cooling of the earth's surface. Also called a nocturnal inversion. [1] |
| 4741 | Radiational Cooling | The process by which the earth's surface and adjacent air cool by emitting infrared radiation. [1] |
| 4742 | Radiocommunications | Any telecommunication by means of radio waves. [14] |
| 4743 | Range: Great Tropic | The difference in height between tropic higher high water and tropic lower low water. [14] |
| 4744 | Range: Small Tropic | The difference in height between tropic lower high water and tropic higher low water. [14] |
| 4745 | Recording Barometer | See barometer. [14] |
| 4746 | Recoverable Station | See station. [14] |
| 4747 | Recovery Of Station | In surveying, the identifying and checking of an original station. This is considered as recovered when its mark (monument) is identified as authentic and proved to be occupying its original site. [14] |
| 4748 | Rectilinear Current | See current: reversing. [14] |
| 4749 | Rectoblique Plotter | A mechanical device intended for rectification of individual rays on tilted or oblique photographs. [14] |
| 4750 | Reduction To Centre | The amount which must be applied to a direction observed at an eccentric station, or to an eccentric signal, to reduce such direction to what it would be if there were no such eccentricity. [14] |
| 4751 | Refraction Of Light | The bending of light rays in passing from one transparent medium into another which has a different index of refraction. [14] |
| 4752 | Refraction: Coastal | A small change in the direction of travel of a radio wave when it crosses a shoreline obliquely due to a difference in conducting and reflecting properties between land and water, and thus velocity. [14] |
| 4753 | Relief Displacement | Displacement of images radially inward or outward with respect to the photograph nadir, according as the ground objects are, respectively, below or above the elevation of the ground nadir. [14] |
| 4754 | Right Reading Image | An image which may be read or observed normally whether in negative or positive form. [14] |
| 4755 | Sailing: Rhumb Line | Any sailing when a rhumb line is involved. [14] |
| 4756 | Saturation (Of Air) | An atmospheric condition whereby the level of water vapor is the maximum possible at the existing temperature and pressure. [1] |
| 4757 | Sediment(S): Bottom | In general all sedimentary material regardless of origin found on or in the submarine bottom, including ballast or other material dumped into the sea by man. More specifically it is limited to unconsolidated mineral and organic material forming the sea bottom, not including coral reefs or bedrocks. [14] |
| 4758 | Selective Absorbers | Substances such as water vapor, carbon dioxide, clouds, and snow that absorb radiation only at particular wavelengths. [1] |
| 4759 | Semidiurnal Current | See current. [14] |
| 4760 | Sequence Of Current | The order of occurrence of the tidal current strengths of a day, with special reference to whether the greater flood immediately precedes or follows the greater ebb. [14] |
| 4761 | Serial Temperatures | The observations required to determine the vertical distribution of temperature and salinity with depth at any one place in the ocean. [14] |
| 4762 | Set Of Observations | A set of two or more observations at different settings of the apparatus made in order to eliminate certain errors which, for the apparatus concerned, are inherent in a single observation. [14] |
| 4763 | Ship Of Opportunity | An expression designating ships of commercial lines employed in gathering oceanographic data. [14] |
| 4764 | Shortwave Radiation | A term most often used to describe the radiant energy emitted from the sun, in the visible and near ultraviolet wavelengths. [1] |
| 4765 | Signal: Topographic | Any object, existing or specially erected, used for the control of topographic survey. [14] |
| 4766 | Sky-Wave Correction | The correction to be applied to the time difference reading of received sky waves to convert it to an equivalent ground wave reading. [14] |
| 4767 | Small Diurnal Range | See range. [14] |
| 4768 | Sounding: Formation | Sounding carried out by two or more ships in formation searching for a reported danger. [14] |
| 4769 | Sounding: Hand Lead | Sounding with hand lead. Hand lead soundings are usually taken from a slowly moving vessel. [14] |
| 4770 | South Magnetic Pole | See magnetic pole. [14] |
| 4771 | Special Purpose Map | See map. [14] |
| 4772 | Specular Reflection | The type of reflection, in optics or microwave theory, characteristic of a highly polished plane surface from which all rays are reflected at an angle equal to the angle of incidence. [14] |
| 4773 | Standard Rain Gauge | A nonrecording rain gauge with an 8-inch diameter collector funnel and a tube that amplifies rainfall by tenfold. [1] |
| 4774 | Station: Subsidiary | A station established to overcome some local obstacle to the progress of a survey, and not to determine position data for the station point. [14] |
| 4775 | Stereometric Camera | See camera. [14] |
| 4776 | Stereoscopic Vision | The particular application of binocular vision which enables the observer to obtain the impression of depth, usually by means of two different perspectives of an object, as two photographs taken from different air stations. [14] |
| 4777 | Stereotriangulation | A triangulation procedure that uses a stereoscopic plotting instrument to obtain the successive orientation of the stereoscopic pairs of photographs into a continuous strip. The spatial solution for the extension of horizontal and/or vertical control using these strip coordinates may be obtained by either graphical or computational procedures. Also called bridging. [14] |
| 4778 | Stream: Rectilinear | See current: reversing. [14] |
| 4779 | Strength Of Current | The phase of a tidal current at which the speed is a maximum; also the speed at this time. [14] |
| 4780 | Stripes (Of Colour) | Areas of contrasting colour separated from one another by straight lines, and used as distinguishing characteristic for navigation marks. In British terminology horizontal stripes are denoted as bands. [14] |
| 4781 | Sub-Bottom Profiler | A form of active, low frequency sonar in which acoustic beams penetrate the bottom. A recorder produces a chart which represents a cross section of the geological structure of the subbottom. See also: echo sounder. [14] |
| 4782 | Sub-Celestial Point | See sub-point. [14] |
| 4783 | Subordinate Station | See station. [14] |
| 4784 | Surface Of Position | A surface on some point of which a craft is located. [14] |
| 4785 | Survey: Exploratory | A survey executed for the purpose of obtaining general information concerning areas about which such information was not, previously, a matter of record. [14] |
| 4786 | Survey: Gravimetric | A survey made to determine the acceleration of gravity at various places on the earth's surface. [14] |
| 4787 | Survey: Large Scale | A hydrographic survey at a large scale. Large scale surveys are usually intended to furnish detailed information for dredging, or other types of harbor improvement. [14] |
| 4788 | Survey: Preliminary | See survey: reconnaissance. [14] |
| 4789 | Survey: Topographic | A survey which has for its major purpose the determination of the configuration (relief) of the surface of the earth and the location of natural and artificial objects thereon. [14] |
| 4790 | Talweg (Or Thalweg) | The line joining the lowest points of a valley throughout its length. Sometimes called valley line. [14] |
| 4791 | Telescope: Meridian | A telescope whose motion along a vertical circle is intended to lie in the plane of the meridian. [14] |
| 4792 | Telluric Current(S) | See current: telluric. [14] |
| 4793 | Temporary Magnetism | See magnetism. [14] |
| 4794 | Terrestrial Equator | See equator. [14] |
| 4795 | Theodolite: Transit | See transit. [14] |
| 4796 | Three-Point Problem | The determination of the horizontal position of a point of observation from data comprising two observed horizontal angles between three objects of known position. The problem is solved either graphically by the use of a three-arm protractor, or analytically by trigonometrical computation. [14] |
| 4797 | Tidal Current Chart | See chart. [14] |
| 4798 | Tide(S): Equatorial | Tides that occur approximately every two weeks when the moon is over the equator. At these times, the moon produces minimum diurnal inequality in the tide. [14] |
| 4799 | Tide(S): Solsticial | Tides occurring near the times of the solstices, when the tropic range is especially large. [14] |
| 4800 | Topographic Station | See station. [14] |
| 4801 | Track: Great-Circle | The track of a craft following a great circle, or a great circle which a craft intends to follow approximately. [14] |
| 4802 | Track: Radar Guided | See radar. [14] |
| 4803 | Triangulation Tower | A triangulation signal consisting of two separate structures, independent of one another an inner structure which supports the theodolite and sometimes the target or signal lamp, and an outer structure which supports the observer and his assistants and sometimes the target or signal lamp. Triangulation towers are used to elevate the line of sight above trees, topographic features, and other obstacles that might interfere with the observations. See bilby steel tower. [14] |
| 4804 | Tropic Of Capricorn | The southern parallel of declination, approximately 23°27' from the celestial equator, reached by the sun at its maximum southerly declination, or the corresponding parallel on the earth. [14] |
| 4805 | Tropical Depression | A mass of thunderstorms and clouds generally with a cyclonic wind circulation of between 20 and 34 knots. [1] |
| 4806 | Uncontrolled Mosaic | A mosaic composed of uncorrected prints, the detail of which has been matched from print to print without ground control or other orientation. [14] |
| 4807 | Underkeel Allowance | The minimum under keel clearance estimated, or specified by a relevant authority for a defined area or vessel type, to account for vessels' static and dynamic characteristics, sea state, chart reliability, and variance from predicted height of tide. [14] |
| 4808 | Underkeel Clearance | The distance between the lowest point of the ship's hull, normally some point on the keel, and the sea floor. [14] |
| 4809 | United Nations (Un) | The major international organization established to maintain international peace and security, to develop friendly relations among nations, to achieve cooperation in solving international problems. [14] |
| 4810 | Vertical Deflection | See deflection of the vertical. [14] |
| 4811 | Vertical Photograph | See photograph. [14] |
| 4812 | Very Close Pack Ice | Sea ice the concentration of which is practically 10/10ths with little if any water present. [14] |
| 4813 | Warning: Navigation | See navigational warning. [14] |
| 4814 | Wave Of Translation | A wave in which the individual particles of the medium are shifted in the direction of wave travel, as ocean waves in shoal waters. Distinguished from an oscillatory wave. [14] |
| 4815 | Wave: Compressional | A wave in an elastic medium which causes an element of the medium to change its volume without undergoing rotation. [14] |
| 4816 | Wellhead: Submerged | A submarine structure projecting some distance above the seabed and capping a temporarily abandoned or suspended oil or gas well. [14] |
| 4817 | Wind Driven Current | See current. [14] |
| 4818 | Younger-Dryas Event | A cold episode that took place about 11,000 years ago, when average temperatures dropped suddenly and portions of the northern hemisphere reverted back to glacial conditions. [1] |
| 4819 | Zenithal Projection | See projection: azimuthal. [14] |
| 4820 | Absolute Orientation | See orientation. [14] |
| 4821 | Accuracy: Repeatable | See repeatable accuracy. [14] |
| 4822 | Aerial Triangulation | See phototriangulation. [14] |
| 4823 | Angle Of Convergence | See parallactic angle. [14] |
| 4824 | Angular Acceleration | See acceleration. [14] |
| 4825 | Antenna: Directional | An antenna for transmitting or receiving signals in, or from, a given direction. [14] |
| 4826 | Anticrepuscular Rays | Bands of light extending across the sky that appear to converge toward the horizon opposite from the sun. [1] |
| 4827 | Apparent Temperature | What the air temperature ?feels like? For various combinations of air temperature and relative humidity. [1] |
| 4828 | Approximate Position | A position that is considered to be less than third-order accuracy, but is generally considered to be within 100 feet (30.5 meters) of its correct geographic location. The method of location may be an indication of the recorded accuracy. [14] |
| 4829 | Arc Of Triangulation | See triangulation: arc of. [14] |
| 4830 | Artificial Satellite | See satellite. [14] |
| 4831 | Astrolabe: Prismatic | An astrolabe consisting of a telescope in a horizontal position, with a prism and artificial horizon attached at its objective end, used for determining astronomic positions. [14] |
| 4832 | Atmosphere: Standard | Conventional reference atmosphere, chosen to represent in a simple way the approximate average condition in the vertical. [14] |
| 4833 | Automatic Tide Gauge | See gauge: tide. [14] |
| 4834 | Axis Of Spirit Level | The line tangent to the surface of a spirit level tube against which the bubble forms, at the center of the graduated scale of the level, and in the plane of the tube and its center of curvature. Also called level axis or spirit level axis. [14] |
| 4835 | Back-Door Cold Front | A cold front moving south or southwest along the atlantic seaboard of the united states. [1] |
| 4836 | Barometer: Recording | Barometer which gives a continuous graphic representation of the atmospheric pressure variations with time. [14] |
| 4837 | Barometric Altimeter | See altimeter. [14] |
| 4838 | Barometric Elevation | See elevation. [14] |
| 4839 | Barometric Levelling | See levelling. [14] |
| 4840 | Beacon: Aeronautical | An aeronautical ground light visible at all azimuths, either continuously or intermittently, to designate a particular point on the surface of the earth. A radio beacon may be coterminous with the aeronautical beacon. [14] |
| 4841 | Beneaped (Or Neaped) | Said of a vessel left aground following a spring high tide. [14] |
| 4842 | Bottom Contour Chart | A chart designed for surface and sub-surface bathymetric navigation seaward of the 100-fathom contour. Bottom configuration is portrayed by depth contours and selected soundings. [14] |
| 4843 | Bottom Relief Survey | A survey conducted to obtain information on the spatial characteristics of the sea bottom relief. [14] |
| 4844 | Broad On The Quarter | Bearing 135° relative (broad on the starboard quarter) or 225° relative (broad on the port quarter). If the bearings are approximate, the expression on the quarter should be used. See also on the quarter. [14] |
| 4845 | Camera: Stereometric | A combination of two cameras mounted with parallel optical axes on a short rigid base; used in terrestrial photogrammetry for making photographs in stereoscopic pairs. [14] |
| 4846 | Cantilever Extension | Phototriangulation from a controlled area to an area of no control. Also, the connection by relative orientation and scaling of a series of photographs in a strip to obtain strip coordinates. [14] |
| 4847 | Carbon Dioxide (Co2) | A colorless, odorless gas whose concentration is about 0.039 percent (390 ppm) in a volume of air near sea level. It is a selective absorber of infrared radiation and, consequently, it is important in the earth's atmospheric greenhouse effect. Solid co2 is called dry ice. [1] |
| 4848 | Carbon Monoxide (Co) | A colorless, odorless, toxic gas that forms during the incomplete combustion of carbon-containing fuels. [1] |
| 4849 | Celestial Navigation | See navigation. [14] |
| 4850 | Centre: Reduction To | See reduction. [14] |
| 4851 | Chart Sounding Datum | The tidal datum to which soundings and drying heights on a chart are referred. It is usually taken to correspond to a low water stage of the tide. Often shortened to chart datum, especially when it is clear that reference is not being made to a horizontal datum. [14] |
| 4852 | Chart: Tidal Current | A chart showing by arrows and numbers the average direction and speed of tidal currents at a particular part of the current cycle. [14] |
| 4853 | Chromatic Aberration | See aberration of light. [14] |
| 4854 | Circle Of Visibility | That circle surrounding an aid to navigation and in which the aid is visible. See range of visibility. [14] |
| 4855 | Circle: Hydrographic | A double-reflecting instrument intended primarily for use in hydrographic survey; enables measurement of angles up to 180°. See also sextant: sounding. [14] |
| 4856 | Cloud Classification | System of distinguishing and grouping clouds according to one or more of the following criteria: a) appearance, b) process of formation, c) common height, d) particulate composition. [14] |
| 4857 | Collimation: Line Of | The line through the optical center of the objective lens of a telescope and the center of the reticle. Also called line of sight, sight line, pointing line or aiming line of the instrument. [14] |
| 4858 | Collimator: Vertical | A telescope so mounted that its collimation axis can be made to coincide with the vertical (or direction of plumb-line). The vertical collimator serves as an optical plumb-line, and may be designed for use in placing a mark on the ground directly under an instrument or in centering an instrument directly over a mark on the ground. [14] |
| 4859 | Compass: Master Gyro | A gyroscopic compass for controlling one or several remote indicators, called gyro repeaters. [14] |
| 4860 | Composite Photograph | See photograph. [14] |
| 4861 | Connection: Geodetic | Observations on one or more stations common to the two different geodetic schemes of triangulation to be incorporated. [14] |
| 4862 | Correction: Sky-Wave | The correction to be applied to the signals received via the ionosphere to convert them to their groundwave equivalent. [14] |
| 4863 | Current(S): Telluric | Natural electric currents that flow on or near the earth's surface in large sheets. Also called earth current. [14] |
| 4864 | Current: Drift Angle | The angle between the true heading and the track of a vessel caused by the action of current. [14] |
| 4865 | Current: Geostrophic | A current existing when the horizontal pressure gradient and the coriolis force are in balance. [14] |
| 4866 | Current: Rectilinear | See current: reversing. [14] |
| 4867 | Current: Semidiurnal | The type of tidal current having two flood and two ebb periods of nearly the same duration during a tidal day. [14] |
| 4868 | Current: Wind Driven | A current formed by the force of the wind. [14] |
| 4869 | Curvature Correction | In astronomy, a correction applied to the mean of a series of observations on a star or planet to take account of the divergence of the apparent path of the star or planet from a straight line. In geodesy, the correction applied in some geodetic work to take account of the divergence of the surface of the earth (spheroid) from a plane. [14] |
| 4870 | Danger To Navigation | Any feature or condition that might hinder, obstruct, endanger or otherwise constitute danger to safe navigation. [14] |
| 4871 | Daylight Saving Time | See time. [14] |
| 4872 | Deep Sea Thermometer | See thermometer. [14] |
| 4873 | Depression: Angle Of | See angle of depression. [14] |
| 4874 | Dip Of A Sea Horizon | The vertical angle, at the eye of an observer, between the horizontal and the line of sight to the sea horizon. [14] |
| 4875 | Direction Theodolite | See theodolite. [14] |
| 4876 | Distortion Of Medium | Changes in the dimensions of surveys or charts due to expansion or contraction of the paper on which the survey or chart is drawn or printed. See also differential shrinkage. [14] |
| 4877 | Drag (Of Theodolite) | A slight movement of the graduated circle produced by the rotation of the alidade. [14] |
| 4878 | Dry Bulb Thermometer | See thermometer. [14] |
| 4879 | Electronic Telemeter | See telemeter. [14] |
| 4880 | Emergent Nodal Point | See nodal point. [14] |
| 4881 | Ensemble Forecasting | A forecasting technique that entails running several forecast models each beginning with slightly different weather information. The forecaster's level of confidence is based on how well the models agree (or disagree) at the end of some specified time. [1] |
| 4882 | Equator: Terrestrial | A great circle of the earth in the plane of the celestial equator, and equidistant from the two poles. [14] |
| 4883 | Equilibrium Argument | The theoretical phase of a constituent of the equilibrium tide. [14] |
| 4884 | Error Of Collimation | The angle between the line of collimation (line of sight) of a telescope and its collimation axis; i.e., the angle by which the line of sight of an optical instrument differs from what it should be. Also called collimation error. [14] |
| 4885 | Ex-Meridian Altitude | See altitude. [14] |
| 4886 | Exploration Drilling | Drilling operations aimed at the exploration of resources. [14] |
| 4887 | Explosive Fog Signal | See fog signal. [14] |
| 4888 | Exterior Orientation | See orientation. [14] |
| 4889 | First Point Of Aries | See equinox. [14] |
| 4890 | First Point Of Libra | See equinox. [14] |
| 4891 | Fixed Angle Sounding | See sounding. [14] |
| 4892 | Frequency Modulation | See modulation. [14] |
| 4893 | Frequency: High (Hf) | See frequency: radio. [14] |
| 4894 | Fusion: Stereoscopic | See stereoscopic fusion. [14] |
| 4895 | Geodetic Coordinates | See coordinates. [14] |
| 4896 | Geographic(Al) Range | See range. [14] |
| 4897 | Graticule Adjustment | The transportation or movement of the graticule in order to change the origin of reference. [14] |
| 4898 | Greenwich Civil Time | See time: Greenwich mean. [14] |
| 4899 | Greenwich Hour Angle | See hour angle. [14] |
| 4900 | Ground Control Point | See control point. [14] |
| 4901 | Height Of Cloud Base | Height above the earth's surface, at a given point, of the base of the lowest cloud whose cloud amount exceeds a given value. Called ceiling in US Terminology. [14] |
| 4902 | Horizon: Closing The | Measuring the last of a series of horizontal angles at a station required to make the series complete around the horizon. See also error of closure of horizon. [14] |
| 4903 | Hydrographic Sextant | See sextant: sounding. [14] |
| 4904 | Hyperbolic Number(S) | Numerical figures characterizing the hyperbolae of a pattern or lattice in a hyperbolic system of radiolocation. [14] |
| 4905 | Incident Nodal Point | See nodal point. [14] |
| 4906 | Inshore Traffic Zone | a routing measure comprising a designated area between the landward boundary of a traffic separation scheme and the adjacent coast, to be used in accordance with the provisions of rule 10(d), as amended, of the international regulations for preventing collisions at sea , 1972 (collision regulations). [14] |
| 4907 | Intensity Of Gravity | See gravity. [14] |
| 4908 | International Waters | A nonlegal term that refers to those waters subject to the high seas freedom of navigation and overflight, i.e., contiguous zone, eez, and high seas. [14] |
| 4909 | Isobaric Chart (Map) | A chart showing variables, such as temperature and wind, on a constant-pressure surface. Variations in height are usually shown by lines of equal height (contour lines). See constant-pressure chart. [1] |
| 4910 | Isolated Danger Mark | in the IALA maritime buoyage system a navigation mark erected on, moored over, or placed immediately adjacent to an isolated danger of limited extent, which has navigable water all around it. [14] |
| 4911 | Latitude: Parametric | The angle at the center of a sphere which is tangent to the spheroid along the geodetic equator, between the plane of the equator and the radius to the point intersected on the sphere by a straight line perpendicular to the plane of the equator and passing through the point on the spheroid whose parametric latitude is defined. Parametric latitude is an auxiliary latitude used in problems of geodesy and cartography. Also called reduced latitude, geometric latitude or eccentric angle. [14] |
| 4912 | Left-Right Indicator | An instrument indicating the orthogonal distance of a position from a pre-defined track. [14] |
| 4913 | Level: Self Aligning | See levelling instrument: self-aligning level. [14] |
| 4914 | Light: Long-Flashing | A flashing light in which a single flash of not less than two seconds duration is regularly repeated. [14] |
| 4915 | Line Of Delimitation | A line drawn on a map or chart depicting the separation of any type of maritime jurisdiction. [14] |
| 4916 | Line Of Equidistance | See median line. [14] |
| 4917 | Log: Electromagnetic | A log consisting of a pulsating magnet mounted on a probe pointing downwards with two contacts on the sides of the probe. The movement of the water through the magnetic field is reflected by the contacts and the ripple of voltage thus induced can be converted to measure the speed of the craft. [14] |
| 4918 | Longitude: Celestial | Angular distance east of the vernal equinox, along the ecliptic; the arc of the ecliptic or the angle at the ecliptic pole between the circle of latitude of the vernal equinox and the circle of latitude of a point on the celestial sphere, measured eastward from the circle of latitude of the vernal equinox, through 360°. [14] |
| 4919 | Low Water Inequality | See diurnal inequality. [14] |
| 4920 | Lunicurrent Interval | The interval between the moon's transit (upper or lower) over the local or Greenwich meridian and a specified phase of the tidal current following the transit. Examples are strength of flood interval and strength of ebb interval, which may be abbreviated to flood interval and ebb interval, re-spectively. The interval is described as local or Greenwich according to whether the reference is to the moon's transit over the local or Greenwich meridian. When not otherwise specified, the reference is assumed to be local. [14] |
| 4921 | Magnetic Compensator | See compensator. [14] |
| 4922 | Magnetic Declination | See variation. [14] |
| 4923 | Magnetic Inclination | See dip. [14] |
| 4924 | Magnetism: Transient | See magnetism: temporary. [14] |
| 4925 | Magnetometer: Cesium | An optical pumping magnetometer which employs a cesium absorption cell. [14] |
| 4926 | Magnetometer: Helium | An optical pumping magnetometer which employs a helium absorption cell. [14] |
| 4927 | Map: Special Purpose | Any map designed primarily to meet specific requirements. [14] |
| 4928 | Maritime Meteorology | Branch of the meteorology which is concerned with the interaction between the sea and atmosphere. [14] |
| 4929 | Mean Range (Of Tide) | The difference in the height between mean high water and mean low water. [14] |
| 4930 | Mercator: Transverse | See projection: transverse Mercator. [14] |
| 4931 | Meridian: Photograph | In photogrammetry, the image on a photograph of any horizontal line in the object space which is parallel to the principal plane. Since all such lines meet at infinity, the image of the meeting point is at the intersection of the principal line and the horizon trace, and all photograph meridians pass through that point. [14] |
| 4932 | Mid-Holocene Maximum | A warm period in geologic history about 5000 to 6000 years ago that favored the development of plants. [1] |
| 4933 | Modulation: Sideband | A particular kind of amplitude modulation in which one of the two frequency bands on both sides of the carrier (and possibly the carrier itself) is suppressed, allowing a considerable reduction of the spectral width of the signal. [14] |
| 4934 | Multiple Sea Sampler | An instrument which comprises six water bottles arranged so that they trip and take water samples at different selected depths from a vessel under way. [14] |
| 4935 | Navigable Semicircle | See dangerous semicircle. [14] |
| 4936 | Navigation: Acoustic | See navigation: sonic. [14] |
| 4937 | Navigation: Inertial | Dead reckoning performed automatically by a device which gives a continuous indication of position by double integration of acceleration since leaving a starting point. [14] |
| 4938 | Navigation: Offshore | Navigation at distance from a coast, in contrast with coastwise navigation. [14] |
| 4939 | New Print (Of Chart) | In US Terminology, a new issue of a chart embodying only minor corrections. Such corrections are applied to the negatives and a new printing plate made. New prints do not render previous printings of the current edition obsolete. [14] |
| 4940 | Noon: Local Apparent | Twelve o'clock local apparent time. Sometimes called high noon. [14] |
| 4941 | North Celestial Pole | See pole: celestial. [14] |
| 4942 | Observation Equation | See equation. [14] |
| 4943 | Ocean Remote Sensing | A kind of remote sensing especially for conducting investigations and surveys of the ocean and the sea. [14] |
| 4944 | One-Way Traffic Lane | See traffic lane. [14] |
| 4945 | Parallax In Altitude | Geocentric parallax of a body at any altitude. The expression is used to distinguish the parallax at the given altitude from the horizontal parallax when the body is in the horizon. [14] |
| 4946 | Parallax: Geocentric | See parallax: diurnal. [14] |
| 4947 | Parallax: Horizontal | In astronomy, the geocentric parallax of a body on the observer's horizon. In photogrammetry, parallax: absolute stereoscopic. [14] |
| 4948 | Parallel Of Altitude | See almucantar. [14] |
| 4949 | Parallel: Photograph | In photogrammetry, the image on a photograph of any horizontal line in the object space which is perpendicular to the principal plane. All photograph parallels are perpendicular to the principal line. The photograph parallel passing through the principal point is the principal parallel and that passing through the isocenter is the isometric parallel. [14] |
| 4950 | Peninsula: Submarine | An elevated portion of the submarine relief resembling a peninsula. The opposite is sac. [14] |
| 4951 | Peripheral Equipment | In computer systems, any unit of equipment, distinct from the central unit, which may provide the system with outside communication. [14] |
| 4952 | Persistence Forecast | A forecast that the future weather condition will be the same as the present condition. [1] |
| 4953 | Phase(S) Of The Moon | The various appearances of the moon during different parts of the synodical month. The cycle begins with new moon or change of the moon at conjunction. The visible part of the waxing moon increases in size during the first half of the cycle until full moon appears at opposition, after which the visible part of the waning moon decreases for the remainder of the cycle. First quarter occurs when the waxing moon is at east quadrature, last quarter when the waning moon is at west quadrature. From last quarter to new and from new to first quarter the moon is crescent; from first quarter to full and from full to last quarter it is gibbous. [14] |
| 4954 | Photograph: Vertical | An aerial photograph made with the camera axis vertical (or as nearly vertical as practicable in an aircraft). [14] |
| 4955 | Piezoelectric Effect | The phenomenon, exhibited by certain crystals, in which mechanical compression produces a potential difference between opposite crystal faces, or, an applied electric field produces corresponding changes in dimensions. [14] |
| 4956 | Point Of Destination | See destination: point of. [14] |
| 4957 | Polar Tundra Climate | A climate characterized by extremely cold winters and cool summers, as the average temperature of the warmest month climbs above freezing but remains below 10°c (50°f). [1] |
| 4958 | Pole: Geographic(Al) | Either of the two points of intersection of the surface of the earth with its axis, labelled n or s to indicate either the north geographical pole or the south geographical pole. [14] |
| 4959 | Polyconic Projection | See projection. [14] |
| 4960 | Position Approximate | Of inexact position. The expression is used principally on charts to indicate that the position of a wreck, shoal, etc., has not been accurately determined or does not remain fixed. Usually shown by the abbreviation 'pa'. [14] |
| 4961 | Pressure: Barometric | Atmospheric pressure as indicated by a barometer. [14] |
| 4962 | Primary Tide Station | See station: tide. [14] |
| 4963 | Probability Forecast | A forecast of the probability of occurrence of one or more of a mutually exclusive set of weather conditions. [1] |
| 4964 | Programming Language | A language used to prepare computer programs, for example Fortran, Pascal and many others. [14] |
| 4965 | Projection: Gnomonic | A perspective projection on a plane tangent to the surface of a sphere having the point of projection at the center of the sphere. The projection is neither conformal nor equal area. It is the only projection on which great circles on the sphere are represented as straight lines. For this reason this projection is used principally for charts for great circle sailing. [14] |
| 4966 | Projection: Mercator | A conformal projection of the cylindrical type. The equator is represented by a straight line true to scale; the geographic meridians are represented by parallel straight lines perpendicular to the line representing the equator; they are spaced according to their distance apart at the equator. The geographic parallels are represented by a second system of straight lines perpendicular to the family of lines representing the meridians, and therefore parallel with the equator. Conformality is achie-ved by mathematical analysis, the spacing of the parallels being increased with the increasing distance from the equator to conform with the expanding scale along the parallels resulting from the meridians being represented by parallel lines. Since rhumb lines appear as straight lines and directions can be measured directly, this projection is widely used in navigation. [14] |
| 4967 | Projection: Zenithal | See projection: azimuthal. [14] |
| 4968 | Quarantine Anchorage | An area where a vessel anchors when satisfying quarantine regulations. [14] |
| 4969 | Radius Of Visibility | See under visibility. [14] |
| 4970 | Range: Small Diurnal | The difference in height between mean lower high water and mean higher low water. [14] |
| 4971 | Reciprocal Levelling | See levelling. [14] |
| 4972 | Recording Anemometer | See anemograph. [14] |
| 4973 | Reflecting Projector | See projector. [14] |
| 4974 | Reflecting Telescope | See telescope. [14] |
| 4975 | Reflection: Angle Of | See angle of reflection. [14] |
| 4976 | Refracting Telescope | See telescope. [14] |
| 4977 | Refraction: Index Of | The ratio of the sine of the angle of incidence to the sine of the angle of refraction. [14] |
| 4978 | Relative Orientation | See orientation. [14] |
| 4979 | Repeating Theodolite | See theodolite. [14] |
| 4980 | Reprint (Of A Chart) | (US Terminology). An issue of a chart the supply of which is approaching exhaustion. The reprint is an exact duplicate of the current issue with no changes in printing or publication data. [14] |
| 4981 | Resource Exploration | The search for economic deposits of minerals, ore, gas, oil or coal. [14] |
| 4982 | Saffir-Simpson Scale | A scale relating a hurricane's winds to the possible damage it is capable of inflicting. It is now called the saffir-simpson hurricane wind scale. [1] |
| 4983 | Sea (Or Lake) Breeze | Wind of coastal regions, blowing by day from a large water surface (sea or lake) towards the land as a result of diurnal heating of the land surface. [14] |
| 4984 | Sea Water: Colour Of | The apparent colour of the surface layers of the sea caused by the reflection of certain components of the visible light spectrum coupled with the effects of dissolved material, concentration of plankton, detritus, or other matter. Colour of oceanic water varies from deep blue to yellow and is expressed by number values which are a variation of the forel scale. Plankton concentrations may cause a temporary appearance of red, white, green, or other colors. Also called water colour. See also discoloured water. [14] |
| 4985 | Seabed Texture Chart | A tracing showing the nature and texture of the bottom, depth contours and seabed features including wrecks and obstructions. Also called bottom texture tracing. [14] |
| 4986 | Sensible Temperature | The sensation of temperature that the human body feels in contrast to the actual temperature of the environment as measured with a thermometer. [1] |
| 4987 | Short-Range Forecast | Generally used to describe a weather forecast that extends from about 6 hours to a few days into the future. [1] |
| 4988 | Shutter: Focal-Plane | A shutter located near the focal plane; usually consisting of a curtain with a slot which is pulled across the focal plane to make the exposure. [14] |
| 4989 | Sidereal Chronometer | See chronometer. [14] |
| 4990 | Signal: Hydrographic | Any object, existing or specially erected, for the control of hydrographic survey. See also sounding mark. [14] |
| 4991 | Snow Squall (Shower) | An intermittent heavy shower of snow that greatly reduces visibility. [1] |
| 4992 | Snow-Albedo Feedback | A positive feedback whereby increasing surface air temperatures enhance the melting of snow and ice in polar latitudes. This reduces the earth's albedo and allows more sunlight to reach the surface, which causes the air temperature to rise even more. [1] |
| 4993 | South Celestial Pole | See pole: celestial. [14] |
| 4994 | Spectral Peak Period | Period of the maximum (peak) energy density in the spectrum. NOTE In practice there is often more than one peak in a spectrum. [15] |
| 4995 | Speed Of Propagation | The speed with which waves of energy travel through or along a medium other than a specially constructed path. [14] |
| 4996 | Spherical Aberration | See aberration of light. [14] |
| 4997 | Station: Main Scheme | A station through which the main computations and adjustments of the survey data are carried and serve for the continued extension of the survey. [14] |
| 4998 | Station: Recoverable | A station artificially marked by well defined natural or artificial objects, whose geographic position has been accurately determined and which has been described. [14] |
| 4999 | Station: Subordinate | One of the places for which tide or tidal current predictions are determined by applying a correction to the predictions of a reference station. A tide or tidal current station at which a short series of observations was made and reduced by comparison with simultaneous observations at a reference station. Called secondary port in British terminology. See station: tide. [14] |
| 5000 | Station: Topographic | A definite point on the earth, whose geographic position has been determined by graphic methods, usually by plane table traverse or graphic triangulation. Also a point located by geodetic methods but with less than third-order accuracy. [14] |
| 5001 | Statistical Forecast | A forecast based on a mathematical/statistical examination of data that represents the past observed behavior of the forecasted weather element. [1] |
| 5002 | Stereophotogrammetry | Photogrammetry utilizing stereoscopic equipment and methods. [14] |
| 5003 | Subsidence Inversion | A temperature inversion produced by compressional warming the adiabatic warming of a layer of sinking air. [1] |
| 5004 | Sulfur Dioxide (So2) | A colorless gas that forms primarily in the burning of sulfur-containing fossil fuels. [1] |
| 5005 | Superior Conjunction | See conjunction. [14] |
| 5006 | Supplemental Control | See control. [14] |
| 5007 | Survey: Geologic(Al) | A survey or investigation of the character and structure of the earth, of the physical changes which the earth's crust has undergone or is undergoing, and of the causes producing those changes. [14] |
| 5008 | Survey: Hydrographic | A survey having for its principal purpose the determination of data relating to bodies of water. A hydrographic survey may consist of the determination of one or several of the following classes of data: depth of water; configuration and nature of the bottom; directions and force of currents; heights and times of tides and water stages; and location of topographic features and fixed objects for survey and navigation purposes. [14] |
| 5009 | Survey: Magnetometer | A survey wherein the earth's magnetic field is mapped by the use of a magnetometer. [14] |
| 5010 | Sustained Wind Speed | Time-averaged wind speed with an averaging duration of 10 min or longer. [15] |
| 5011 | Synoptic Meteorology | Branch of meteorology which is concerned with the study of meteorological elements in space. It is based on the analysis of the synoptic charts on which are plotted synoptic observations for the purpose of the weather analysis or weather forecast. [14] |
| 5012 | Synoptic Observation | Meteorological observation made at the same time (synoptic hour) at numerous stations to obtain general representation of the state of the atmosphere at the given time. [14] |
| 5013 | Terrestrial Latitude | See latitude. [14] |
| 5014 | Thermal Circulations | Air flow resulting primarily from the heating and cooling of air. [1] |
| 5015 | Thermometer: Maximum | Thermometer used for measuring the highest temperature attained during a given interval of time, for example, a day. [14] |
| 5016 | Thermometer: Minimum | Thermometer used for measuring the lowest temperature attained during a given interval of time, for example, a day. [14] |
| 5017 | Tidal Current Signal | See signal. [14] |
| 5018 | Tide Staff: Multiple | A succession of tide staffs on a sloping shore, so placed that the vertical graduations on the several staffs form a continuous scale with reference to the same datum. [14] |
| 5019 | Tide: Meteorological | A change in water level caused by local meteorological conditions, in contrast to an astronomical tide caused by the attraction of the sun and moon. [14] |
| 5020 | Tides: Mixed Diurnal | Diurnal tides which become semidiurnal with a considerable decrease of range when the moon's declination is small. [14] |
| 5021 | Time: Apparent Solar | Time measured by the apparent diurnal motion of the (true) sun. Also called true solar time, and often apparent time. [14] |
| 5022 | Time: Astronomic(Al) | Solar time in a day (astronomical day) that begins at noon. [14] |
| 5023 | Time: Local Apparent | The apparent solar time for the meridian of the observer. [14] |
| 5024 | Time: Local Sidereal | The sidereal time for the meridian of the observer. [14] |
| 5025 | Trade Wind Inversion | A temperature inversion frequently found in the subtropics over the eastern portions of the tropical oceans. [1] |
| 5026 | Transforming Printer | A specially designed projection printer of fixed geometry used for transforming the oblique components of a coupled camera installation, a multiple-lens camera, or a panoramic camera onto a plane perpendicular to the axis of the system. [14] |
| 5027 | Transit Magnetometer | See magnetometer. [14] |
| 5028 | Triangulation Signal | See signal. [14] |
| 5029 | Triangulation: Flare | A method of triangulation in which simultaneous observations are made on parachute flares. This method is used for extending triangulation over lines too long to be observed by ordinary methods. [14] |
| 5030 | Underwater Acoustics | A special field of technical acoustics dealing with the physics of sound propagation in the water. [14] |
| 5031 | Wet-Bulb Temperature | The lowest temperature that can be obtained by evaporating water into the air. [1] |
| 5032 | Wet-Bulb Thermometer | See thermometer. [14] |
| 5033 | Wire Angle Indicator | A device used to measure the angle of the sounding wire, or the oceanographic wire, from the vertical. It consists of a protractor with a weighted plumb arm. The indicator is suspended from the wire at two points and the plumb arm points to the wire angle. Also called inclinometer. [14] |
| 5034 | Acceleration: Angular | The rate of change of angular velocity. [14] |
| 5035 | Actual Vapor Pressure | The pressure exerted by the water vapor molecules in a given volume of air. Also see vapor pressure. [1] |
| 5036 | Aerial Photogrammetry | See photogrammetry. [14] |
| 5037 | Altimeter: Barometric | A sensitive aneroid barometer calibrated to read the height above a pressure datum according to the standard atmospheric pressure-to-height relationship. [14] |
| 5038 | Archipelagic Sea Lane | Sea lanes designated by an archipelagic state for the passage of ships and aircraft. [14] |
| 5039 | Automated Cartography | The performance of cartographic functions in a fully automatic mode. [14] |
| 5040 | Bearing: Great Circle | The initial direction of a great circle through two terrestrial points, expressed as angular distance from a reference direction. Bearings obtained by any form of radiant energy are great-circle bearings. [14] |
| 5041 | Calling The Soundings | Announcement made by leadsman when heaving the lead. [14] |
| 5042 | Camera: Multiple Lens | A camera with two or more lenses, with the axes of the lenses systematically arranged at fixed angles in order to cover a wide field by simultaneous exposures in all chambers. [14] |
| 5043 | Chart Amendment Patch | See chartlet. [14] |
| 5044 | Chart Comparison Unit | A device which provides simultaneous, superimposed views of a chart and radar scope. [14] |
| 5045 | Chronometer: Sidereal | A chronometer that indicates sidereal time at a given place, or that corresponding to a given meridian. [14] |
| 5046 | Chronometer: Standard | The chronometer with which the others aboard a vessel are compared and to which all observations involving time are referred. [14] |
| 5047 | Circle Of Declination | See hour circle. [14] |
| 5048 | Circle Of Uncertainty | A circle having as its center a position, however determined, and as its radius the maximum probable error of the position; a circle within which a craft is considered to be located. [14] |
| 5049 | Compensator: Magnetic | A magnet, piece of soft iron such as a sphere or iron bar, placed in a binnacle or in vicinity of a magnetic compass for reducing magnetic deviation to a minimum. Also called compass corrector or corrector magnet. See flinders bar, heeling magnet, quadrantal correctors. [14] |
| 5050 | Conjunction: Inferior | The conjunction of an inferior planet and the sun when the planet is between the earth and the sun. [14] |
| 5051 | Conjunction: Superior | The conjunction of an inferior planet and the sun when the sun is between the earth and the planet. [14] |
| 5052 | Consolidated Pack Ice | Pack ice in which the concentration is 10/10 (8/8) and the floes are frozen together. [14] |
| 5053 | Control: Astronomical | Control determined from astronomical observations. [14] |
| 5054 | Control: Supplemental | Points established by subordinate surveys, to relate aerial photographs used in mapping with the system of geodetic control. The points must be positively photo-identified, that is, the points on the ground must be positively correlated with their images on the photographs. [14] |
| 5055 | Coordinates: Geodetic | Quantities which define the horizontal position of a point on the spheroid of reference with respect to the planes of geodetic equator and of a selected geodetic meridian. See latitude: geodetic and longitude: geodetic. [14] |
| 5056 | Coring (Or Core) Tube | See core barrel. [14] |
| 5057 | Dead Reckoning Tracer | A device that automatically provides a graphical record of the dead reckoning track. See course recorder. [14] |
| 5058 | Declination: Magnetic | See variation. [14] |
| 5059 | Deviation: Quadrantal | Deviation which changes its sign (e or w) approximately each 90° change of heading. It is caused by induced magnetism in horizontal soft iron. [14] |
| 5060 | Directional Gyroscope | See gyroscope. [14] |
| 5061 | Dispersion (Of Light) | The separation of white light into its different component wavelengths. [1] |
| 5062 | Elevation: Barometric | An elevation determined with a barometer. [14] |
| 5063 | Equal Area Projection | See projection. [14] |
| 5064 | Equation: Observation | A condition equation which connects interrelated unknowns by means of an observed function. [14] |
| 5065 | Equator: Astronomical | A line connecting points having 0° astronomical latitude. [14] |
| 5066 | Equipotential Surface | A surface having the same potential of gravity at every point. [14] |
| 5067 | Equivalent Projection | See projection: equal area. [14] |
| 5068 | First Point Of Cancer | See solstice. [14] |
| 5069 | Fog Signal: Explosive | Detonation of an explosive used as a navigational warning during low visibility. [14] |
| 5070 | Gravity Anomaly Chart | See chart. [14] |
| 5071 | Gravity: Direction Of | The direction indicated by a plumb line. It is perpendicular to the surface of the geoid. Also called direction of the force of gravity. [14] |
| 5072 | Gravity: Intensity Of | The magnitude with which gravity acts, expressed in suitable units, usually as an acceleration, in gals; as a force, in dynes. [14] |
| 5073 | Great Circle: Primary | See primary great circle. [14] |
| 5074 | Heliocentric Parallax | See parallax: annual. [14] |
| 5075 | High Water Inequality | See diurnal inequality. [14] |
| 5076 | Horizontal Photograph | See photograph. [14] |
| 5077 | Hydrostatic Levelling | The transfer of level between two points by the use of a pipe filled with water laid on the sea bed with vertical sections at each end. [14] |
| 5078 | Hydrostatic Stability | See stability: static. [14] |
| 5079 | Identification Beacon | See beacon. [14] |
| 5080 | Impersonal Micrometer | See micrometer: transit. [14] |
| 5081 | Inclination: Magnetic | See dip. [14] |
| 5082 | Katabatic (Fall) Wind | Any wind blowing downslope. It is usually cold. [1] |
| 5083 | Latitude: Terrestrial | Angular distance from the equator, measured northward or southward through 90° and labelled n or s to indicate the direction of measurement. [14] |
| 5084 | Levelling: Barometric | A method of determining differences of elevation from differences of atmospheric pressure observed with a barometer. [14] |
| 5085 | Levelling: Reciprocal | Trigonometric levelling wherein vertical angles have been observed at both ends of the line to eliminate errors. [14] |
| 5086 | Light: Equal-Interval | A light with all durations of light and darkness equal. The term 'equal-interval light' has been replaced byisophase light in many countries. [14] |
| 5087 | Light: Group-Flashing | A flashing light in which a group of two or more flashes, which are specified in number, is regularly repeated. [14] |
| 5088 | Light: Quick-Flashing | A light exhibiting without interruption very rapid regular alternations of light and darkness. [14] |
| 5089 | Light: Short-Flashing | A flashing light having individual flashes of less than two seconds duration. [14] |
| 5090 | Lithographic Transfer | A proof of design or type matter pulled with special transfer ink on transfer paper from a lithographic image or a relief image. Such proofs are used to transfer an image to the plate or stone. [14] |
| 5091 | Love Wave (Or Q-Wave) | See wave. [14] |
| 5092 | Magnetometer: Transit | An instrument used primarily for observing the declination of the earth's magnetic field. [14] |
| 5093 | Marine Nature Reserve | (US Marine sanctuary). An officially designated area in which there may be restrictions on entry, fishing, anchoring, and other activities in order to protect the marine environment. [14] |
| 5094 | Medium Frequency (Mf) | See frequency: radio. [14] |
| 5095 | Medium-Range Forecast | Generally used to describe a weather forecast that extends from about 3 to 8.5 days into the future. [1] |
| 5096 | Meridian: Terrestrial | See meridian: astronomical. [14] |
| 5097 | Meridional Difference | The difference between the meridional parts of any two given parallels. [14] |
| 5098 | Modulation: Amplitude | The process of changing the amplitude of a carrier wave in accordance with the variations of a modulating wave. [14] |
| 5099 | Modulation: Frequency | Angle modulation of a sine-wave carrier in which the instantaneous frequency of the modulated wave differs from the carrier frequency by an amount proportional to the instantaneous value of the modulating wave. [14] |
| 5100 | Multispectral Imagery | Images obtained simultaneously in a number of discrete bands in the electromagnetic spectrum. [14] |
| 5101 | Multispectral Scanner | A remote-sensing device which is capable of recording data in the ultraviolet and visible portions of the electromagnetic spectrum, as well as the infrared. [14] |
| 5102 | Navigation: Celestial | Navigation with the aid of celestial bodies. Also called astro-navigation. [14] |
| 5103 | Navigation: Coastwise | Navigation in the vicinity of a coast, in contrast with offshore navigation. [14] |
| 5104 | Navigation: Submarine | Navigation of a submarine, whether submerged or surfaced. [14] |
| 5105 | No-Bottom Sounding(S) | See sounding. [14] |
| 5106 | Nodal Point: Emergent | See nodal point. [14] |
| 5107 | Nodal Point: Incident | See nodal point. [14] |
| 5108 | Nonharmonic Constants | Tidal or tidal current constants such as lunitidal intervals, ranges, and inequalities, which can be derived directly from observation without regard to the harmonic constituents. [14] |
| 5109 | Observation(S): Tidal | A series of measurements taken in order to provide the information required for the reduction of soundings, and the data for tidal prediction and investigation. [14] |
| 5110 | Oceanographic Section | A successive series of oceanographic stations carried out in a specified direction. [14] |
| 5111 | Oceanographic Station | See station. [14] |
| 5112 | Omnidirectional Range | See omnirange. [14] |
| 5113 | Orientation: Absolute | In photogrammetry, the scaling, levelling, and orientation to ground control (in a photogrammetric instrument) of a relatively oriented stereoscopic model or group of models. [14] |
| 5114 | Orientation: Exterior | In photogrammetry, the determining (analytically or in a photogrammetric instrument) of the position of the camera station and the attitude of the taking camera at the instant of exposure. In stereoscopic instrument practice, exterior orientation is divided into two parts, relative and absolute orientation. Also called outer orientation. [14] |
| 5115 | Orientation: Relative | In photogrammetry, the determining (analytically or in a photogrammetric instrument) of the position and attitude of one of a pair of overlapping photographs with respect to the other photograph. [14] |
| 5116 | Origin Of Coordinates | See coordinates: origin of. [14] |
| 5117 | Photograph: Composite | In aerial photography, a photograph made by assembling the separate photographs, made by the several lenses of a multiple lens camera in simultaneous exposure, into the equivalent of a photo-graph taken with a single wide-angle lens. [14] |
| 5118 | Picture Control Point | See control point. [14] |
| 5119 | Polar Ice Cap Climate | A climate characterized by extreme cold, as every month has an average temperature below freezing. [1] |
| 5120 | Potential Temperature | In oceanography, the temperature that a water sample would attain if raised adiabatically to the sea surface. For the deepest points of the ocean, which are just over 10 000 meters, the adiabatic cooling would be less than 1.5° c. [14] |
| 5121 | Pressure: Atmospheric | Pressure (force per unit area) exerted by the atmosphere, on any surface, by virtue of its weight: it is numerically equal to the weight of a vertical column of air above the surface of unit base area, extending to the outer limit of the atmosphere. [14] |
| 5122 | Pressure: Hydrostatic | The pressure at a given depth due to the weight of the water column above that depth. [14] |
| 5123 | Prime Vertical Circle | The vertical circle through the east and west points of the horizon. Often shortened to prime vertical. [14] |
| 5124 | Projection: Geometric | See projection: perspective. [14] |
| 5125 | Projection: Polyconic | A projection having the central geographic meridian represented by a straight line, along which the spacing for lines representing the geographic parallels is proportional to the distances apart of the parallels; the parallels are represented by arcs of circles which are not concentric, but whose centers lie on the line representing the central meridian, and whose radii are determined by the lengths of the elements of cones which are tangent along the parallels. All meridians except the central one are curved. This projection is neither conformal nor equal area but it has been widely used for maps of small areas because of the ease with which it can be constructed. [14] |
| 5126 | Projector: Reflecting | In photogrammetry, an instrument by means of which the image of an aerial photograph can be projected onto a map. By varying the position of the projector lens, the scale of the projected image can be varied, and, by tilting the table top, compensation can be made for any tilt in the photograph. [14] |
| 5127 | Proportional Dividers | An instrument consisting in its simple form of two legs pointed at both ends and provided with an adjustable pivot, so that for any given pivot setting, the distance between one set of pointed ends always bears the same ratio to the distance between the other set. A change in the pivot changes the ratio. The dividers are used in transferring measurements between charts or other drawings which are not at the same scale. [14] |
| 5128 | Protractor: Three Arm | An instrument consisting essentially of a circle graduated in degrees, to which is attached one fixed arm and two arms pivoted at the center and provided with clamps so that they can be set at any angle to the fixed arm, within the limits of the instrument. It is used for finding a ship's position, when the angles between three fixed and known points are measured. In British terminology, a perspex (or transparent plastic) device used when the marks are too close for the use of a station pointer. This instrument has replaced the cust protractor. [14] |
| 5129 | Pulse Radio Altimeter | See altimeter: radio. [14] |
| 5130 | Pulse Repetition Rate | The rate at which recurrent pulses are transmitted, usually expressed in pulses per second. [14] |
| 5131 | Punch Register System | System involving the use of prepunched holes in the flat and plate and a set of plastic pins or buttons which are used in registering succeeding flats, positioning the image on the plate, and positioning the plate on the press. See also registration. [14] |
| 5132 | Quality Of The Bottom | See bottom: nature of. [14] |
| 5133 | Range: Geographic(Al) | The greatest distance at which a light can be seen as a function of the curvature of the earth and the heights of the light source and the observer. [14] |
| 5134 | Reconnaissance Survey | See survey. [14] |
| 5135 | Refraction Correction | A correction due to refraction, particularly such a correction to a sextant altitude, due to atmospheric refraction. [14] |
| 5136 | Retentivity: Magnetic | See magnetic retentivity. [14] |
| 5137 | Reticle (Or Reticule) | A system of wires, hairs, threads, etched lines, or the like, placed normal to the axis of a telescope at its principal focus, by means of which the telescope is sighted on a star, signal, or target, or by means of which appropriate readings are made on some scale, such as a levelling or stadia rod. See also cross wires, graticule, diaphragm. In photogrammetry, a mark such as a cross or system of lines lying in the image plane of a viewing apparatus and used singly as a reference mark in certain types of monocular instruments or as one of a pair to form a floating mark as in certain types of stereoscopes. [14] |
| 5138 | Sag Correction (Tape) | See tape: sag correction. [14] |
| 5139 | Sailing: Great Circle | Any sailing when a great circle track is involved. [14] |
| 5140 | Satellite: Artificial | An object placed by man in orbit around the earth, or other celestial body. See navigational (or navigation) satellite. [14] |
| 5141 | Sextant: Hydrographic | See sextant: sounding. [14] |
| 5142 | Shallow Water Tide(S) | See tide. [14] |
| 5143 | Signal: Tidal Current | A signal or message conveying information on condition of tidal current in the area in question. [14] |
| 5144 | Signal: Triangulation | A rigid structure erected close or over a triangulation station. Also any object, natural or artificial, whose position is obtained in a triangulation survey. The term may be applied to a structure whose position is determined by triangulation, but whose primary purpose is to serve later in a hydro-graphic or topographic survey, when it may become known as a hydrographic or topographic signal. [14] |
| 5145 | Sounding(S): Detached | Those soundings, including least depths on shoals, whose positions were accurately located. See position: detached. [14] |
| 5146 | Sounding: Fixed Angle | A method consisting in sounding along the arcs of circles subtended by two objects whose position is known. For each arc, an angle remains constant (fixed angle) and the second angle, between another pair of objects, defines the position of the vessel along the arc. By varying the fixed angle successively by equal amounts, a series of lines of sounding covering the area systematically can be run. See fixed angle plot. [14] |
| 5147 | Station: Astronomical | A point on the earth whose position has been determined by observations of celestial bodies. [14] |
| 5148 | Station: Intersection | In surveying, an object whose horizontal position is determined by observations from other stations, no observations being made at the object itself. Where the object is observed from only two stations, the position is termed a no check position as there is no proof that such observations are free from blunders. Intersection stations are either objects which would be difficult to occupy with an instrument, or survey signals whose positions can be determined with sufficient accuracy without being occupied. Also called intersected point. [14] |
| 5149 | Steady-State Forecast | A weather prediction based on the past movement of surface weather systems. It assumes that the systems will move in the same direction and at approximately the same speed as they have been moving. Also called trend forecasting. [1] |
| 5150 | Supplementary Station | See station. [14] |
| 5151 | Survey: Oceanographic | A study or examination of any physical, chemical, biological, geological or geophysical condition in the ocean, or any part of it. An expedition to gather data, samples or information to conduct such studies or examination. [14] |
| 5152 | Taiga (Boreal Forest) | The open northern part of the coniferous forest. Taiga also refers to subpolar climate. [1] |
| 5153 | Telemeter: Electronic | An electronic device that measures the phase difference or transit time between a transmitted electromagnetic impulse of known frequency and speed and its return. [14] |
| 5154 | Telescope: Reflecting | A telescope which collects light by means of a concave mirror. [14] |
| 5155 | Telescope: Refracting | A telescope which collects light by means of a lens or system of lenses. [14] |
| 5156 | Temperature Inversion | N oceanography, a layer in which temperature increases with depth. Also called inversion layer. [14] |
| 5157 | Template (Or Templet) | A pattern or guide, usually constructed of paper, plastic, or metal, used to shape, delimit, or locate an area. A device used in radial triangulation to represent the aerial photograph; the template provides a record of the directions of radials taken from the photograph. [14] |
| 5158 | Terrestrial Longitude | See longitude. [14] |
| 5159 | Terrestrial Magnetism | See geomagnetism. [14] |
| 5160 | Terrigenous Sediments | Deposits consisting of debris derived from the erosion of land areas and usually deposited in the shallow parts of the sea. [14] |
| 5161 | Theodolite: Direction | A theodolite in which the graduated horizontal circle remains fixed during a series of observations, the telescope being pointed on a number of signals or objects in succession, and the direction of each read on the circle, usually by the use of micrometer microscopes. [14] |
| 5162 | Thermometer: Deep Sea | A thermometer for ascertaining the temperature of sea water at any depth. See thermometer: protected reversing, thermometer: reversing, thermometer: unprotected reversing. [14] |
| 5163 | Thermometer: Dry-Bulb | That of the two thermometers of a psychrometer whose bulb is bare and which indicates the air temperature. [14] |
| 5164 | Thermometer: Wet-Bulb | That of the two thermometers of a psychrometer whose bulb is wet and covered by a film of pure water or ice. [14] |
| 5165 | Tidal (Or Tide) Cycle | A complete set of tidal conditions, as those occurring during a tidal day, lunar month or metonic cycle. [14] |
| 5166 | Time: Daylight Saving | A variation of zone time, usually one hour ahead of that time. Sometimes called summer time. [14] |
| 5167 | Time: Greenwich Civil | See time: Greenwich mean. [14] |
| 5168 | Track: Dead Reckoning | A line representing successive dead reckoning positions of a craft. [14] |
| 5169 | Transient Thermocline | See thermocline. [14] |
| 5170 | Traverse: Plane Table | A graphical traverse executed by plane table methods. [14] |
| 5171 | Triangulation: Radial | See radial triangulation. [14] |
| 5172 | Underwater Navigation | See navigation. [14] |
| 5173 | Unifilar Magnetometer | See magnetometer. [14] |
| 5174 | Unrecoverable Station | See station. [14] |
| 5175 | Variation Of The Pole | A wandering of the poles of the figure of the earth with respect to its poles of rotation. [14] |
| 5176 | Visibility: Radius Of | The radius of a circle limiting the area in which an object can be seen under specified conditions. [14] |
| 5177 | World Geodetic System | A global geodesic reference system developed by the USA for satellite position fixing and recommended by IHO for hydrographic and cartographic use. [14] |
| 5178 | Active Tracking System | A satellite system which operates by transmission of signals to and receipt of responses from the satellite. [14] |
| 5179 | Alt-Azimuth Instrument | An instrument equipped with both horizontal and vertical graduated circles, for the observation of horizontal and vertical directions or angles. [14] |
| 5180 | Altimeter: Pulse Radio | See altimeter: radio. [14] |
| 5181 | Astronomic(Al) Azimuth | See azimuth. [14] |
| 5182 | Astronomic(Al) Control | See control. [14] |
| 5183 | Astronomic(Al) Equator | See equator. [14] |
| 5184 | Astronomic(Al) Station | See station. [14] |
| 5185 | Astronomic(Al) Transit | See transit. [14] |
| 5186 | Atmospheric Refraction | See refraction. [14] |
| 5187 | Atmospheric Stagnation | A condition of light winds and poor vertical mixing that can lead to a high concentration of pollutants. Air stagnations are most often associated with fair weather, an inversion, and the sinking air of a high-pressure area. [1] |
| 5188 | Axis Of Optical System | The line formed by the coinciding principal axes of the series of optical elements. [14] |
| 5189 | Baseline: Archipelagic | Archipelagic baselines are straight lines joining the outermost points of the outermost islands and drying reefs of an archipelago. [14] |
| 5190 | Beacon: Identification | An aeronautical and/or radio and/or light beacon emitting a coded signal by means of which a particular reference point can be identified. [14] |
| 5191 | Bimetallic Thermometer | A temperature-measuring device usually consisting of two dissimilar metals that expand and contract differentially as the temperature changes. [1] |
| 5192 | Bottom Characteristics | Designations used on survey and nautical charts to indicate the consistency, colour, and classification of the sea bottom. Also called nature of the bottom, character of the bottom. [14] |
| 5193 | Calibration Of Compass | See swinging ship. [14] |
| 5194 | Chain Of Triangulation | See triangulation: arc of. [14] |
| 5195 | Chart: Gravity Anomaly | A chart on which current gravity anomalies are graphically depicted. [14] |
| 5196 | Chronometer Correction | The amount to be added algebraically to the time of the chronometer to obtain the correct time. [14] |
| 5197 | Collimation Adjustment | The process of bringing the line of collimation of a telescope into close agreement with the collimation axis. [14] |
| 5198 | Continental Borderland | A region adjacent to a continent, normally occupied by or bordering a continental shelf, highly irregular, with depths well in excess of those typical of a continental shelf. [14] |
| 5199 | Coordinates: Celestial | Any set of coordinates used to define a point on the celestial sphere. The horizon, celestial equator and ecliptic systems of celestial coordinates are based on the celestial horizon, celestial equator and ecliptic respectively, as the primary great circle. [14] |
| 5200 | Coordinates: Origin Of | The point of intersection of the coordinate axes, from which the coordinates are reckoned. In mathematical treaties, this origin is usually given the coordinates 0,0; in surveying, however, it is standard practice to give this origin, coordinates having large positive numerical values, thereby avoiding the use of negative coordinates. Also called point of origin. See coordinates: false. [14] |
| 5201 | Coordinates: Spherical | A system of polar coordinates in which the origin is the center of a sphere and the points all lie on the surface of a sphere. The polar axis of such a system cuts the sphere at its two poles. [14] |
| 5202 | Cross Wires (Or Hairs) | Wires or etched lines, at right angles, held at the focal plane of an astronomical or sighting telescope. See also reticle. [14] |
| 5203 | Cylindrical Projection | See projection. [14] |
| 5204 | Difference Of Latitude | The angular distance between the parallels of two places measured on a meridian. [14] |
| 5205 | Differential Levelling | See levelling. [14] |
| 5206 | Differential Shrinkage | In mapping, the difference in unit contraction along the grain structure of the material as compared to the unit contraction across the grain structure; frequently refers to photographic film and papers and to map materials in general. [14] |
| 5207 | Double Zenith Distance | See zenith distance. [14] |
| 5208 | Dust Devil (Whirlwind) | A small but rapidly rotating wind made visible by the dust, sand, and debris it picks up from the surface. It develops best on clear, dry, hot afternoons. [1] |
| 5209 | Electric Submerged Log | See log. [14] |
| 5210 | Ellipsoid Of Reference | See reference spheroid. [14] |
| 5211 | Extinction Coefficient | A measure of the space rate of diminution or extinction, of any transmitted light. In oceanography, the measure of attenuation of downward directed light radiation in the sea. [14] |
| 5212 | Floating Triangulation | See triangulation. [14] |
| 5213 | Frequency Of Soundings | See density of soundings. [14] |
| 5214 | Frequency: Medium (Mf) | See frequency: radio. [14] |
| 5215 | Geocentric Coordinates | See coordinates. [14] |
| 5216 | Graphic Control Survey | See survey. [14] |
| 5217 | Gyroscope: Directional | A gyroscopic device used to indicate a selected horizontal direction for a limited time. It requires periodic resetting dependent upon the gyro precession rate or change in the desired heading or horizontal direction. [14] |
| 5218 | Installation: Offshore | Man-made structure usually built for the exploration or exploitation of marine resources, marine scientific research, tide observations, etc. [14] |
| 5219 | International Shipping | Shipping engaged on international voyages. [14] |
| 5220 | Interrogator-Responsor | See interrogator and responsor. [14] |
| 5221 | Isogonal (Or Isogonic) | (Adj.). Having equal angles. [14] |
| 5222 | Isogonal (Or Isogonic) | (n.). See isogonic line. [14] |
| 5223 | Lagging Of The Tide(S) | The periodic retardation in the time of occurrence of high and low water due to changes in the relative positions of the moon and the sun. [14] |
| 5224 | Lagging Of The Tide(S) | The retardation in the time of occurrence of high and low water due to changes in the relative positions of the moon and the sun. The opposite effect is called priming of the tide(s). See also daily retardation. [14] |
| 5225 | Latitude: Astronomical | Angular distance between the direction of gravity and the plane of the equator. Astronomical latitude is the latitude which results directly from observations on celestial bodies, uncorrected for deflection of the vertical. [14] |
| 5226 | Layer Depth Prediction | Predetermining the depth to the top of the thermocline over a given ocean area. [14] |
| 5227 | Light: Group-Occulting | An occulting light in which a group of two or more eclipses, which are specified in number, is regularly repeated. [14] |
| 5228 | Line Of Constant Scale | Any line on a photograph which is parallel to the true horizon or to the isometric parallel. [14] |
| 5229 | Longitude: Terrestrial | The intercepted arc of equator, or the angle at the pole, between the meridian of a point on the earth, and the prime meridian, measured eastward or westward from the prime meridian through 180° and labelled e or w to indicate the direction of measurement. [14] |
| 5230 | Low Oblique Photograph | See photograph. [14] |
| 5231 | Magnetic Annual Change | The amount of secular change in the earth's magnetic field which occurs in one year. Also referred to as annual change. [14] |
| 5232 | Magnetism: Terrestrial | See geomagnetism. [14] |
| 5233 | Magnetometer: Unifilar | A magnetometer, designed for use on shore, employed to measure the horizontal intensity of the earth's magnetism; it can also be used to determine variation. [14] |
| 5234 | Mean Daily Temperature | The average of the highest and lowest temperature for a 24-hour period. [1] |
| 5235 | Mean Sounding Velocity | Mean values for velocity of sound through the vertical water column of specific depths based on different velocities of sound in different sections of the column. These values yield more nearly correct depths when sonic depth finders are used. The velocity of sound at any specific depth may differ considerably from the mean. [14] |
| 5236 | Meridian: Astronomical | A line on the surface of the earth connecting points having the same astronomical longitude. Because the deflection of the vertical is not the same at all points, an astronomical meridian is an irregular line, not lying in a single plane. Also called terrestrial meridian. [14] |
| 5237 | Micrometer: Impersonal | See micrometer: transit. [14] |
| 5238 | Military Practice Area | See exercise area. [14] |
| 5239 | Navigation: Electronic | Navigation by means of electronic equipment. The expression 'electronic navigation' is more inclusive than radio navigation, since it includes navigation involving any electronic device or instrument. [14] |
| 5240 | Navigation: Hyperbolic | Navigation by the use of hyperbolic lines of position. [14] |
| 5241 | Navigation: Long Range | Navigation requiring only aids usable at long range, relatively few of which could provide world coverage. The opposite is short range navigation. [14] |
| 5242 | Navigation: Underwater | The navigation of a submerged vessel. Occasionally called submarine navigation. [14] |
| 5243 | Navigational Astronomy | See astronomy: nautical. [14] |
| 5244 | Navigational Planet(S) | See planet(s): navigational. [14] |
| 5245 | New Edition (Of Chart) | In British terminology, a new printing of an existing chart embodying the latest information received in the hydrographic department. The chart is entirely revised throughout and modernized in style, all copies of the chart in circulation being cancelled. When a new edition is published the large and small corrections dates are removed (these corrections being embodied in the new edition). In US Terminology, a new printing of an existing chart embodying corrections that have become so extensive or of such importance to navigation as to render all previous printings obsolete. [14] |
| 5246 | Nitrogen Dioxide (No2) | A reddish-brown gas, produced by natural bacterial action in soil and by combustion processes at high temperatures. In the presence of sunlight, it breaks down into nitric oxide and atomic oxygen. In polluted air, nitrogen dioxide acts as an agent in the production of photochemical smog. [1] |
| 5247 | Oceanographic Features | Physical qualities characterizing the state of environment in water bodies of the world's oceans. These features include temperature and salinity, electric conductivity, density, hydrostatic pressure, transparency, the range and character of tidal and other water level oscillations, the speed and direction of currents, the characteristics of waves and ice, etc. [14] |
| 5248 | Omnidirectional Beacon | See omnirange. [14] |
| 5249 | Orthometric Correction | The correction to elevations which takes into account the spheroidal shape of the earth and brings the elevations to their true height above mean sea level. [14] |
| 5250 | Parallax: Heliocentric | See parallax: annual. [14] |
| 5251 | Parallel: Astronomical | A line on the surface of the earth which has the same astronomical latitude at every point. Because the deflection of the vertical is not the same at all points on the earth, an astronomical parallel is an irregular line, not lying in a single plane. [14] |
| 5252 | Permeability: Magnetic | See magnetic permeability. [14] |
| 5253 | Photogrammetric Camera | See camera. [14] |
| 5254 | Photogrammetric Survey | See survey. [14] |
| 5255 | Photogrammetry: Aerial | Photogrammetry utilizing aerial photographs. [14] |
| 5256 | Photograph Coordinates | See coordinates. [14] |
| 5257 | Photograph: Horizontal | Photograph taken with the camera axis horizontal. [14] |
| 5258 | Position: Astronomical | A point on the earth whose coordinates have been determined as a result of observation of celestial bodies. The expression is usually used in connection with positions on land determined with great accuracy for survey purposes. A point on the earth, defined in terms of astronomical latitude and longitude. [14] |
| 5259 | Preferred Channel Mark | A distinctive lateral mark used to indicate both the point at which a channel divides and the channel that has been designated as preferred channel. [14] |
| 5260 | Primary Air Pollutants | Air pollutants that enter the atmosphere directly. [1] |
| 5261 | Priming Of The Tide(S) | The acceleration in the times of occurrence of high and low water due to changes in the relative positions of the moon and the sun. The opposite effect is called lagging of the tides. [14] |
| 5262 | Program (Or Programme) | The complete sequence of computer instructions and routines necessary to solve a data processing problem. [14] |
| 5263 | Projection: Equivalent | See projection: equal area. [14] |
| 5264 | Radio Acoustic Ranging | Determining distance by a combination of radio and sound, the radio being used to determine the instant of transmission or reception of the sound, and distance being determined by the time of transit of sound, usually in water. Also called radio acoustic sound ranging. See distance finding station, echo ranging, sonobuoy. [14] |
| 5265 | Radio Signals: List Of | See list of radio signals. [14] |
| 5266 | Range Height Indicator | A scope which simultaneously indicates range and height of a radar target. [14] |
| 5267 | Reduction To Sea Level | A reduction applied to a measured horizontal length on the earth's surface to reduce it to the surface of the sea level datum. [14] |
| 5268 | Reversing Water Bottle | See water bottle. [14] |
| 5269 | Root Mean Square Error | See error: standard. [14] |
| 5270 | Sea Bottom Temperature | The temperature measured at or close to sea floor. [14] |
| 5271 | Secondary Tide Station | See station: tide. [14] |
| 5272 | Semicircular Deviation | See deviation. [14] |
| 5273 | Short Range Navigation | See navigation. [14] |
| 5274 | Side Scan Sonar Mosaic | An assembly of side scan sonar images whose edges have been cut or torn and matched to form a continuous side scan sonar image. [14] |
| 5275 | Simultaneous Altitudes | Altitudes of two or more celestial bodies observed at the same time. [14] |
| 5276 | Sounding(S): No Bottom | (US Terminology). Soundings where the bottom was not reached because the general depths were too great for the method of measurement. [14] |
| 5277 | Split Line Of Sounding | A line of sounding run to fill a void when the maximum spacing of principal lines is exceeded. [14] |
| 5278 | Station: Oceanographic | The geographic location at which any set of oceanographic observations are gathered. The station may be occupied by a mobile platform (a ship) or a fixed platform such as a tower. [14] |
| 5279 | Station: Supplementary | An auxiliary station, established to increase the number of control stations in a given area, or to place a station in a desired location where it is impracticable or unnecessary to establish a principal station. Also called secondary station. [14] |
| 5280 | Station: Trigonometric | See station: triangulation. [14] |
| 5281 | Station: Unrecoverable | A triangulation station that cannot be found and cannot be included in the triangulation to connect it with a new datum. Sometimes called 'lost' station. [14] |
| 5282 | Stationary Wave Theory | A theory which assumes that the basic tide motion in the open ocean consists of a system of standing wave oscillations; progressive waves are of secondary importance except where the tide advances into tributary waters. [14] |
| 5283 | Submarine Sound Signal | See sound signal. [14] |
| 5284 | Submarine Transit Lane | a lane where submarines may navigate under water or at the surface. [14] |
| 5285 | Subpermanent Magnetism | See magnetism: permanent. [14] |
| 5286 | Subtropical Jet Stream | The jet stream typically found between 20° and 30° latitude at altitudes between 12 and 14 km. [1] |
| 5287 | Surface Boundary Layer | See ground layer. [14] |
| 5288 | Survey: Reconnaissance | A hasty preliminary survey of a region made to provide some advance information regarding the area which may be useful, pending the execution of more complete surveys. Also called preliminary survey. [14] |
| 5289 | Temperature Lapse Rate | Rate of decrease of temperature with increasing height; usually an average rate over a distance, for example 100 meters, is considered. [14] |
| 5290 | Terrestrial Navigation | The kind of navigation which uses marks ashore for positioning. [14] |
| 5291 | Theodolite: Face(S) Of | See face(s) of theodolite. [14] |
| 5292 | Thermocline: Transient | A small decrease in vertical temperature observed above the thermocline. It is a short-term phenomenon associated primarily with diurnal heating and wind mixing. [14] |
| 5293 | Thermometer: Reversing | A deep-sea thermometer that records temperature at the desired depth upon being inverted and thereafter retains its reading until returned to the first position. Reversing thermometers are generally used in pairs on water bottles. [14] |
| 5294 | Thermometric Levelling | See levelling. [14] |
| 5295 | Three-Point Fix Method | One of the principal methods used on inshore hydrographic surveys for establishing the position of the survey vessel. It involves the measurement with sextants of two angles between three known stations, the middle station being common to both angles, and plotting the vessel's position gra-phically with a three-arm protractor. [14] |
| 5296 | Tide: Leeward (Or Lee) | A tidal current setting in the same direction as that in which the wind is blowing. Also called leeward tidal current. [14] |
| 5297 | Traverse: Astronomical | A traverse in which the geographic(al) positions of the stations are obtained from astronomical observations, and lengths and azimuths of lines are obtained by computation. [14] |
| 5298 | Tropic Lower Low Water | The lower low water of tropic tides. [14] |
| 5299 | Unidirectional Antenna | See antenna. [14] |
| 5300 | Universal Time 0 (Ut0) | The uncorrected time of the earth's rotation as measured by the transit of stars across the observer's meridian. This rotation is referred to a fiducial mark on the ecliptic which approximates the position of the mean sun. [14] |
| 5301 | Universal Time 1 (Ut1) | Ut0 corrected for polar motion. [14] |
| 5302 | Universal Time 2 (Ut2) | Ut1 corrected for seasonal variations in the earth's rotation. [14] |
| 5303 | Want Of Correspondence | See parallax: y-. [14] |
| 5304 | Wave: Love (Or Q-Wave) | A transverse wave propagated along the boundary of two elastic media which both have rigidity, i.e. Both media must be capable of propagating transverse waves. A surface seismic wave in which the particles of an elastic medium vibrate transverse to the direction of the wave's travel, with no vertical component. [14] |
| 5305 | Weather Chart (Or Map) | See chart. [14] |
| 5306 | Absorption: Atmospheric | Transformation of radiant energy into thermal, mechanical, electrical, etc. Energy, by interaction with atmospheric constituents. [14] |
| 5307 | Acceleration Of Gravity | The acceleration of a freely falling body caused by the force of gravity. [14] |
| 5308 | Age Of Phase Inequality | The time interval between new or full moon and the maximum effect of these phases upon the range of tide or the speed of the tidal current. [14] |
| 5309 | Air Quality Index (Aqi) | An index of air quality that provides daily air pollution concentrations. Intervals on the scale relate to potential health effects. [1] |
| 5310 | Antenna: Unidirectional | An antenna having a single well-defined direction of maximum radiation intensity or maximum gain. [14] |
| 5311 | Arc To Chord Correction | The quantity used by seamen to correct a great circle bearing of a point b from a point a to a Mercator bearing, and usually referred to as the half convergency on the Mercator projection, this quantity is equal to half the convergency, on the spheroid, of the meridians through the two points being considered. Also called conversion angle. See convergence of the meridians. [14] |
| 5312 | Arctic Oscillation (Ao) | A reversal of atmospheric pressure over the arctic that produces changes in the upper-level westerly winds over northern latitudes. These changes in upper-level winds influence winter weather patterns over North America, Greenland, and Europe. [1] |
| 5313 | Artificial Installation | See installation offshore. [14] |
| 5314 | Astronomic(Al) Latitude | See latitude. [14] |
| 5315 | Astronomic(Al) Meridian | See meridian. [14] |
| 5316 | Astronomic(Al) Parallel | See parallel. [14] |
| 5317 | Astronomic(Al) Position | See position. [14] |
| 5318 | Astronomic(Al) Traverse | See traverse. [14] |
| 5319 | Astronomic(Al) Triangle | The triangle on the celestial sphere formed by arcs of great circles connecting the celestial pole, the zenith and the celestial body. Also called navigational triangle. [14] |
| 5320 | Astronomic(Al) Twilight | See twilight. [14] |
| 5321 | Azimuth: Astronomic(Al) | The angle between the astronomic meridian plane of the observer and the plane containing the observed point and the vertical of the observer. [14] |
| 5322 | Beacon: Omnidirectional | See omnirange. [14] |
| 5323 | Bench Mark (Benchmarks) | A permanent, stable object containing a marked point of known elevation with respect to a datum used as a reference level for tidal observations or as a control point for levelling. [14] |
| 5324 | Calibrated Focal Length | See focal length. [14] |
| 5325 | Camera: Photogrammetric | A general term applicable to cameras used in any of the several branches of photogrammetry. [14] |
| 5326 | Centering (Or Centring) | The placing of an instrument with its vertical axis in the vertical through the ground mark. The setting of lenses of an optical instrument in such a manner that their optical axes are in the same straight line. [14] |
| 5327 | Chart Evaluation Survey | The chart evaluations surveys (CES) program is designed to: 1. Resolve all deficiencies reported or discovered. (a deficiency is defined as charted information that can be made more complete through field examination, or information which should be charted but is not.) 2. Evaluate the adequacy/accuracy of hydrographic information on existing charts. 3. Verify or revise information published in the appropriate coast pilot. 4. Conduct user evaluation and public relations efforts to provide an awareness of products and obtain user input. [14] |
| 5328 | Check Lines Of Sounding | Sounding lines run after completing the main system of sounding lines for the purpose of checking them. See also cross lines of sounding. [14] |
| 5329 | Climatological Forecast | A weather forecast, usually a month or more in the future, which is based upon the climate of a region rather than upon current weather conditions. [1] |
| 5330 | Compass Adjustment Buoy | A buoy placed at a favorable location to assist a vessel to adjust its compass or swing ship. Also called swinging buoy. See also swinging ship. [14] |
| 5331 | Continental Shelf Limit | The limit of the continental shelf or continental margin determined in accordance with the provisions of the united nations convention on the law of the sea. [14] |
| 5332 | Continuous Strip Camera | See camera. [14] |
| 5333 | Controls Of Temperature | The main factors that cause variations in temperature from one place to another. [1] |
| 5334 | Coordinates: Geocentric | Coordinates that define the position of a point with respect to the center of the earth. See latitude: geocentric. The term 'geocentric longitude' is never used, as the quantity which it would designate is the same as geodetic longitude. [14] |
| 5335 | Coordinates: Photograph | A system of coordinates, either rectangular or polar, to define the position of a point on a photograph. [14] |
| 5336 | Corrected Establishment | See lunitidal interval. [14] |
| 5337 | Correction Of Soundings | The correction of the observed depths for any departure from true depth due to the method of sounding or to a fault in the measuring apparatus. See also reduction of soundings. [14] |
| 5338 | Correction: Atmospheric | The statistical removal of meteorological effects from mean sea level changes. [14] |
| 5339 | Correction: Ionospheric | A correction for errors introduced by ionospheric refraction occurring when signals travel through the ionosphere. [14] |
| 5340 | Cross Lines Of Sounding | Sounding lines run approximately at right angles to those of normal direction, frequently useful when examining shoals. Cross lines are also run after completing the main system of sounding lines, with the purpose of checking them. [14] |
| 5341 | Cruise Line Of Sounding | See track line of sounding. [14] |
| 5342 | Datum: Vertical Control | Any level surface (e.g., mean sea level) taken as a surface of reference from which to reckon elevations. Also called datum level, reference level, reference plane, levelling datum, datum for heights. See also datum plane. [14] |
| 5343 | Dead Reckoning Position | See position. [14] |
| 5344 | Deviation: Semicircular | Deviation which changes sign (e or w) approximately each 180° change of heading. [14] |
| 5345 | Dip (Or Dipping) Needle | A magnetic needle suspended in such a manner as to be free to rotate about a horizontal axis. See dip circle. [14] |
| 5346 | Discrepancy In Position | The difference between a reckoned and an observed position at the same time. [14] |
| 5347 | Eccentricity Of Ellipse | The ratio of the distance between the center and a focus of an ellipse to the length of its semi-major axis. [14] |
| 5348 | Error: Root Mean Square | See error: standard. [14] |
| 5349 | Estimated Position (Ep) | See position. [14] |
| 5350 | Facility (Navigational) | See aid to navigation. [14] |
| 5351 | Geographic(Al) Latitude | See latitude. [14] |
| 5352 | Geographic(Al) Meridian | See meridian. [14] |
| 5353 | Geographic(Al) Parallel | See parallel. [14] |
| 5354 | Geographic(Al) Position | See position. [14] |
| 5355 | Grade Correction (Tape) | See tape: grade correction. [14] |
| 5356 | High Oblique Photograph | See photograph. [14] |
| 5357 | Highland (Or Highlands) | High or elevated land; a lofty headland or cliff. The mountainous or elevated part of any country; occasionally also in the names of geographical districts. [14] |
| 5358 | Hydrostatic Equilibrium | The state of the atmosphere when there is a balance between the vertical pressure gradient force and the downward pull of gravity. [1] |
| 5359 | Hydrostatic Instability | See instability: static. [14] |
| 5360 | Indian Spring Low Water | An arbitrary tidal datum approximating the level of the mean of the lower low water at spring tides. It was first used in waters surrounding India. Also called Indian tide plane. [14] |
| 5361 | International Date Line | See date line. [14] |
| 5362 | Interpupillary Distance | The distance between centers of the eye pupils of an individual. Also called eye base and used interchangeable with interocular distance. [14] |
| 5363 | Ionospheric Disturbance | A sudden outburst of ultraviolet light on the sun, known as a solar flare, which produces abnormally high ionization in the region of the d-layer. The result is a sudden increase in radio wave absorption, with particular severity in the upper medium and lower high frequencies. It has negligible effects on the heights of the reflecting/refracting layers and, consequently, upon critical frequencies, but enormous transmission may occur. [14] |
| 5364 | Landslide (Or Landslip) | The sliding down of a mass of land on a mountain or cliff-side; land which has so fallen. [14] |
| 5365 | Levelling (Or Leveling) | The operation of determining differences of elevation between points on the surface of the earth; the determination of the elevation of points relative to some arbitrary or natural level surface called a datum. Also called differential levelling. [14] |
| 5366 | Levelling: Thermometric | The determination of elevations above sea level from observed values of the boiling point of water. See hypsometer. [14] |
| 5367 | Light (Or Lighted) Buoy | See buoy. [14] |
| 5368 | Light: Group Very Quick | A light in which very quick flashes are combined in groups including the same number of flashes (repetition rate : 80-159 per minute) and in which groups are repeated at regular intervals. [14] |
| 5369 | Log: Electric Submerged | An electrically-operated log installed inside the hull of the vessel with a tube extending through the hull into the water. [14] |
| 5370 | Longitude: Astronomical | The angle between the plane of the celestial meridian and the plane of an initial meridian, arbitrarily chosen. Astronomical longitude is the longitude which results directly from observations on celestial bodies, uncorrected for deflection of the vertical. [14] |
| 5371 | Magnetic Field Strength | See magnetic field intensity. [14] |
| 5372 | Magnetic Lines Of Force | Closed lines indicating by their direction the direction of magnetic influence. [14] |
| 5373 | Magnetic Observation(S) | See observation. [14] |
| 5374 | Magnetic Secular Change | The temporal variation in the value of a magnetic element which occurs over a period of years. [14] |
| 5375 | Magnetism: Subpermanent | See magnetism: permanent. [14] |
| 5376 | Magnetometer: Flux-Gate | An instrument which uses a wire wound saturable core inductor to measure the earth's magnetic field. [14] |
| 5377 | Maritime Polar Air Mass | An air mass characterized by low temperatures and high humidity. [1] |
| 5378 | Mean Annual Temperature | The average temperature at any given location for the entire year. [1] |
| 5379 | Mean Low Water (M.L.W.) | The average height of all low waters at a place over a 19-year period. [14] |
| 5380 | Middle-Latitude Cyclone | A cyclonic storm that most often forms along a front in middle and high latitudes. Also called a middle- latitude cyclonic storm, a depression, and a low. It is not a tropical storm or hurricane. See extratropical cyclone. [1] |
| 5381 | Middle-Latitude Cyclone | A cyclonic storm that most often forms along a front in middle and high latitudes. Also called a middle- latitude cyclonic storm, a depression, and a low. It is not a tropical storm or hurricane. See extratropical cyclone. [1] |
| 5382 | Multi-Beam Echo Sounder | a type of swath(e) sounding system in which the equipment emits a timed pulse of sound that is narrow in the fore-aft direction and wide in the across track direction. The reflected sound is received by several receivers arranged as an array. By use of signal processing of the signal received at combinations of the receivers a much larger number, potentially many hundreds, of acoustic receive beam angles are formed. For each receive beam the time interval between emission and reception of the reflected sound is converted into a range. Geometry is then used to convert each range and receive beam angle to depths and also to position these depths within the swath(e) on the sea floor. Mbes systems may also be referred to as beam-formers. [14] |
| 5383 | Multicell Thunderstorms | Thunderstorms often in a line, each of which may be in a different stage of its life cycle. [1] |
| 5384 | Navigation: Short Range | Navigation employing only aids usable at short ranges. The opposite is long range navigation. [14] |
| 5385 | Navigational Parameters | All data characterizing the position and motion of a vessel in a system of coordinates. [14] |
| 5386 | Night Effect (Or Error) | See error: polarization. [14] |
| 5387 | Nomogram (Or Nomograph) | A diagram showing, to scale, the relationship between several variables in such manner that the value of one which corresponds to known values of the others can be determined graphically. See conversion scale, conversion table. [14] |
| 5388 | North Geographical Pole | See pole: geographical. [14] |
| 5389 | Odometer (Or Hodometer) | An instrument for measuring the distance travelled by a craft. See also speedometer. [14] |
| 5390 | Omnidirectional Antenna | See antenna. [14] |
| 5391 | Orthographic Projection | See projection. [14] |
| 5392 | Parallel Of Declination | A circle of the celestial sphere parallel to the celestial equator. Also called celestial parallel. [14] |
| 5393 | Photogrammetric Control | See control. [14] |
| 5394 | Photograph: Low Oblique | An oblique photograph in which the apparent horizon is not included within the field of view. [14] |
| 5395 | Photograph: Terrestrial | A photograph taken by a camera located on the ground. Sometimes called ground photograph. [14] |
| 5396 | Planet(S): Navigational | The four planets commonly used for celestial observations: Venus, Mars, Jupiter, and Saturn. [14] |
| 5397 | Precipitation Intensity | Amount of precipitation collected in unit time interval. See rainfall amount. [14] |
| 5398 | Prognostic Chart (Prog) | A chart showing expected or forecasted conditions, such as pressure patterns, frontal positions, contour height patterns, and so on. [1] |
| 5399 | Projection: Cylindrical | A projection produced by projecting the geographical meridians and parallels onto a cylinder which is tangent to (or intersects) the surface of a sphere, and then developing the cylinder into a plane. [14] |
| 5400 | Projection: Perspective | The representation of a figure on a surface, either plane or curved, by means of projecting lines emanating from a single point, which may be infinity. Also called geometric projection. [14] |
| 5401 | Properties Of Sea Water | See sea water, salinity. [14] |
| 5402 | Quarter-Diurnal Tide(S) | See tide. [14] |
| 5403 | Radiative Forcing Agent | Any factor (such as increasing greenhouse gases and variations in solar output) that can change the balance between incoming energy from the sun and outgoing energy from the earth and the atmosphere. [1] |
| 5404 | Rectangular Coordinates | See coordinates. [14] |
| 5405 | Refraction: Atmospheric | Refraction resulting when a ray of radiant energy passes obliquely through the atmosphere. It may be called astronomical refraction if the ray enters the atmosphere from outer space, or terrestrial refraction if it emanates from a point on or near the surface of the earth. [14] |
| 5406 | Regression Of The Nodes | Precessional motion of a set of nodes. The expression is used principally with respect to the moon, the nodes of which make a complete westerly revolution in approximately 18.6 years. [14] |
| 5407 | Representative Fraction | See scale: natural. [14] |
| 5408 | Run A Line Of Soundings | (v.t.). To obtain soundings along a line of sounding, for surveying purposes. [14] |
| 5409 | Sargasso (Or Sargassum) | A certain type of seaweed, or more generally, a large floating mass of this seaweed. [14] |
| 5410 | Semidiameter Correction | A correction due to semidiameter, particularly that sextant altitude correction resulting from observation of the upper or lower limb of a celestial body, rather than the center of that body. [14] |
| 5411 | Short-Term Distribution | Probability distribution of a variable within a short interval of time during which conditions are assumed to be statistically constant. NOTE The interval chosen is most often the duration of a sea state. [15] |
| 5412 | Slide (Or Sliding) Rule | A device used for performing rapid computations involving multiplication, division, proportion, roots, and powers. It has a body like a ruler, but with a sliding section. Both body and sliding section are graduated with numbers according to logarithmic scales. [14] |
| 5413 | Slope And Height Factor | In the measurement of distances with tellurometer, a factor to be reckoned when reducing distances to the spheroid. It takes into account the mean height of the stations (master and remote units) and the slope of the line. [14] |
| 5414 | Slope Correction (Tape) | See tape: grade correction. [14] |
| 5415 | Sound Signal: Submarine | A sound signal transmitted through water. [14] |
| 5416 | South Geographical Pole | See pole: geographical. [14] |
| 5417 | Survey: Graphic Control | A skeleton survey made by plane table for the purpose of (a) locating the hydrographic signals, (b) locating additional control from aerial surveys and clarification of indefinite detail on photographs, (c) a combination of the two. [14] |
| 5418 | Survey: Photogrammetric | A survey utilizing either terrestrial or aerial photographs. [14] |
| 5419 | Synoptic Chart (Or Map) | See chart (or map): weather. [14] |
| 5420 | Tide-Predicting Machine | An instrument that computes, sometimes for years in advance, the times and heights of high and low waters at a reference station by mechanically summing the harmonic constituents of which the tide is composed. [14] |
| 5421 | Tide-Producing Force(S) | That part of the gravitational attraction of a celestial body which is effective in producing the tides on earth. The sun and moon are the principal astronomic bodies that have a tide-producing effect. The force varies approximately as the mass of the attracting body and inversely as the cube of its distance. Also called tide-generating force. [14] |
| 5422 | Traffic Separation Line | see separation zone [14] |
| 5423 | Traffic Separation Zone | See separation zone [14] |
| 5424 | Transitional Water Wave | See wave. [14] |
| 5425 | Triangulation: Floating | In hydrographic surveying, a triangulation that may be carried out by means of anchored buoys when surveying at such a distance from the land that the signals on the shore cannot be directly used for locating the soundings. Floating triangulation can be either connected to and extended from the stations of a shore triangulation or of a fully floating type in which case the positions of the buoys are obtained by means of observations and measurements taken at sea. Buoys are anchored in such a position as to provide a framework for surveying the area. [14] |
| 5426 | Triangulation: Order Of | See triangulation classification. [14] |
| 5427 | Trigonometric Levelling | See levelling. [14] |
| 5428 | Tropic Higher Low Water | The higher low water of tropic tides. [14] |
| 5429 | Tropic Lower High Water | The lower high water of tropic tides. [14] |
| 5430 | Tropospheric Scattering | Diffusion of electromagnetic waves when traversing the troposphere. See also: scattering. [14] |
| 5431 | Ultrasonic Depth Finder | See echo sounder. [14] |
| 5432 | Underway (Or Under Way) | (adv.). Without moorings; not secured in any way to the ground or a wharf. In motion, particularly the start of such motion after a standstill. [14] |
| 5433 | Undulation Of The Geoid | The distance between the mathematical reference spheroid and the geoid. [14] |
| 5434 | Visual Line Of Position | A line of position determined by visual observation of a landmark, aid to navigation, etc. [14] |
| 5435 | Water Bottle: Reversing | A water bottle specially designed for use in deep sea waters. The bottle is lowered by wire and can be closed watertight at any desired depth, by means of a messenger allowed to slide down the wire and strike the reversing mechanism making the bottle turn upside down. Thus the enclosed water sample is not contaminated by water at higher levels or lost by leakage after the bottle is brought on board. Reversing thermometers are attached to reversing water bottles. See ekman bottle and nansen bottle. [14] |
| 5436 | Wollaston Current Meter | A current meter similar but much larger and heavier than the ekman current meter. It is equipped with recording mechanisms and is suitable for measuring currents up to six knots. The wollaston current meter is designed for use from ships at anchor. [14] |
| 5437 | Zenith Distance: Double | A value of twice the zenith distance of an object, obtained by observation and not by mathematical process. [14] |
| 5438 | Antenna: Omnidirectional | An antenna having essentially uniform response in azimuth and a directional pattern in elevation. [14] |
| 5439 | Archipelagic Baseline(S) | See baseline. [14] |
| 5440 | Astronomic(Al) Longitude | See longitude. [14] |
| 5441 | Automatic Volume Control | See automatic gain control. [14] |
| 5442 | Between-The-Lens Shutter | See shutter. [14] |
| 5443 | Broken Telescope Transit | See transit. [14] |
| 5444 | Buoy: Light (Or Lighted) | A buoy with a light having definite characteristics for detection and identification during darkness. See characteristics of light. [14] |
| 5445 | Calibration: Direct Base | The calibration of a positioning system with the help of one or more baselines of known length, which is determined with an instrument having an accuracy superior to that of the positioning system. [14] |
| 5446 | Camera: Continuous-Strip | A camera in which a continuous-strip exposure is made by rolling the film continuously past a narrow slit opening at a speed proportional to the ground speed of the aircraft. [14] |
| 5447 | Characteristics Of Light | All particularities of a light, such as colour, period, group number, visibility, height above sea level and character. Also called light characteristics. See also group. [14] |
| 5448 | Chart (Or Map): Synoptic | See chart (or map): weather. [14] |
| 5449 | Chart: Radionavigational | A chart with additional details for the determination of a vessel's position with the aid of radionavigation systems. [14] |
| 5450 | Circle Of Equal Altitude | A small circle on the surface of the earth at every point of which, at the instant of observation, the observed celestial body (sun, star, or planet) has the same altitude and, therefore, the same zenith distance. [14] |
| 5451 | Circum-Meridian Altitude | See altitude: ex-meridian. [14] |
| 5452 | Clearance: Safe Overhead | The height above the vertical control datum at which the highest points of a ship can pass under an overhead power cable without risk of electrical discharge from the cable to the ship or without making contact with a bridge. [14] |
| 5453 | Configuration Of Terrain | The topography of a region. [14] |
| 5454 | Control: Photogrammetric | Control established by photogrammetric methods, as distinguished from control established by ground methods. Also called minor control. [14] |
| 5455 | Coordinates: Plane Polar | The distance and direction from a central point of reference to a point whose position is being defined. The point of reference is termed the pole or origin; the line (distance) connecting the origin with the point whose position is being defined is the radius vector; and the angle between the fixed line (polar axis) which the direction is referred to and the radius vector is the vectorial angle. [14] |
| 5456 | Coordinates: Rectangular | Coordinates on any system in which the axes of reference intersect at right angles. [14] |
| 5457 | Correction: Relativistic | A correction for errors introduced by relativistic effects of the clock rates of positioning systems. [14] |
| 5458 | Declinational Inequality | See diurnal inequality. [14] |
| 5459 | Distance Finding Station | A radio beacon equipped with a synchronized sound signal to provide a means of determining distances from the source of the sound, by measuring the difference in the time of reception of the signals. [14] |
| 5460 | Double Meridian Distance | See meridian distance. [14] |
| 5461 | Equinoxes: Precession Of | See precession of the equinoxes. [14] |
| 5462 | Evaporation (Mixing) Fog | Fog produced when sufficient water vapor is added to the air by evaporation, and the moist air mixes with relatively drier air. The two common types are steam fog, which forms when cold air moves over warm water, and frontal fog, which forms as warm raindrops evaporate in a cool air mass. [1] |
| 5463 | Explosive Anchorage Area | An area set apart for anchored ships discharging or receiving explosives. [14] |
| 5464 | First Point Of Capricorn | See solstice. [14] |
| 5465 | Fish (Or Fishing) Stakes | Poles or stakes placed in shallow water to outline fishing grounds or to catch fish. [14] |
| 5466 | Focal Length: Calibrated | An adjusted value of the equivalent focal length computed to distribute the effect of lens distortion over the entire field used in an aerial camera. [14] |
| 5467 | Focal Length: Equivalent | The distance measured along the axis of lens from the rear nodal point to the plane of best average definition over the entire field used in an aerial camera. [14] |
| 5468 | Geographic(Al) Longitude | See longitude. [14] |
| 5469 | Gyroscopic Stabilization | Equilibrium in the attitude and/or course of a ship or airborne vehicle maintained by the use of gyroscopes. Also, the maintenance (by the use of gyroscopes) of a camera in a desired attitude within an airborne vehicle. [14] |
| 5470 | Height Of Eye Correction | See dip correction. [14] |
| 5471 | Higher Low Water (H.L.W) | The higher of two low waters occurring during a tidal day if diurnal inequality prevails. [14] |
| 5472 | Horizontal Control Datum | The position on the spheroid of reference assigned to the horizontal control (triangulation and traverse) of an area and defined by (1) the position (latitude and longitude) of one selected station in the area, and (2) the azimuth from the selected station to an adjoining station. See also datum: geodetic. [14] |
| 5473 | Interlines (Of Sounding) | Those sounding lines running between the normally spaced lines usually when the bottom is known or suspected to be irregular or if more detailed information about the sea bottom relief is required. [14] |
| 5474 | Isoclinal (Or Isoclinic) | (Adj.). Of or pertaining to equal magnetic dip. [14] |
| 5475 | Isotropic (Or Isotropus) | (Adj.). Having the same physical properties in all directions. [14] |
| 5476 | Latitude: Geographic(Al) | A general term, applying alike to astronomical and geodetic latitudes. [14] |
| 5477 | Length Correction (Tape) | See tape: length correction. [14] |
| 5478 | Levelling: Trigonometric | The determination of differences of elevations by means of observed vertical angles, combined with lengths of lines. [14] |
| 5479 | Lower Low Water (L.L.W.) | The lower of two low waters occurring during a tidal day if the diurnal inequality prevails. [14] |
| 5480 | Lower Low Water Interval | See lunitidal interval. [14] |
| 5481 | Lowest Astronomical Tide | The lowest tide level which can be predicted to occur under average meteorological conditions and under any combination of astronomical conditions. [14] |
| 5482 | Magnetic Field Intensity | The magnetic force exerted on a unit magnetic pole placed at any specified point of space. It is a vector quantity. Its direction is taken as the direction toward which a north magnetic pole would tend to move under the influence of the field. Also called magnetic intensity, magnetic field streng-th. [14] |
| 5483 | Marcq St. Hilaire Method | The establishing of a line of position from the observation of the altitude of a celestial body, and the calculation of its altitude and azimuth by the use of an assumed position. First introduced by Commandant Marcq St. Hilaire of the french navy. See intercept, sub-point. Also referred to as Saint Hilaire method or intercept method. [14] |
| 5484 | Mean High Water (M.H.W.) | The average height of all high waters at a place over a 19-year period. [14] |
| 5485 | Meridian: Geographic(Al) | A general term, applying alike to an astronomical or a geodetic meridian. [14] |
| 5486 | Multiple Lens Photograph | See photograph. [14] |
| 5487 | Narrow-Beam Echo Sounder | A sounder with a transducer of small aperture (typically 2° to 5°) required for high resolution mapping. [14] |
| 5488 | Navigational Observation | Observations necessary to fix the position of a vessel. [14] |
| 5489 | Nor'Easter (Northeaster) | A name given to a strong, steady wind from the northeast that is accompanied by rain and inclement weather. It often develops when a storm system moves northeastward along the coast of North America. [1] |
| 5490 | Observation(S): Magnetic | Measurement of any of the magnetic elements. [14] |
| 5491 | Oceanographic Slide Rule | A specially designed slide rule used for calculating the correction of thermal expansion of a deep sea reversing thermometer. [14] |
| 5492 | Parallel: Geographic(Al) | A line on the earth having the same latitude at every point. The term is applicable alike to an astronomical parallel or to a geodetic parallel. [14] |
| 5493 | Perigean Range (Of Tide) | The average of all monthly tide ranges occurring at the time of perigee. It is larger than the mean range, where the type of tide is either semidiurnal or mixed, and is of no practical significance where the type of tide is diurnal. [14] |
| 5494 | Photograph Perpendicular | The perpendicular from the interior perspective center to the plane of the photograph. [14] |
| 5495 | Photograph: High Oblique | An oblique photograph in which the apparent horizon is included within the field of view. [14] |
| 5496 | Polar Orbiting Satellite | A satellite whose orbit closely parallels the earth's meridian lines and thus crosses the polar regions on each orbit. [1] |
| 5497 | Position: Dead Reckoning | The position of a craft determined by dead reckoning, or by advancing a previous position for courses and distances. [14] |
| 5498 | Position: Geographic(Al) | The position of a point on the surface of the earth expressed in terms of latitude and longitude, either astronomical or geodetic. A sub-point. [14] |
| 5499 | Projection: Orthographic | A perspective azimuthal projection in which the projecting lines, emanating from a point at infinity, are perpendicular to a tangent plane. This projection is used chiefly in nautical astronomy for interconverting coordinates of the celestial equator and horizon systems. [14] |
| 5500 | Projection: Orthomorphic | See projection: conformal. [14] |
| 5501 | Radar Conspicuous Object | An object which returns a strong radar echo. [14] |
| 5502 | Raster Data Presentation | Method of digitally representing data of an image by a matrix-like scheme of pixels. [14] |
| 5503 | Recession Of A Shoreline | Landward movement of the shoreline. Also called retrogression of a beach. [14] |
| 5504 | Refraction: Astronomical | The apparent displacement of an object that results from light rays from a source outside the atmosphere being bent in passing the atmosphere. This results in all objects appearing to be higher above the horizon than they actually are. [14] |
| 5505 | Retired Line Of Position | A line of position which has been moved backward along the course line to correspond with a time previous to that at which the line was established. Called a transferred position line in British terminology. [14] |
| 5506 | Retrogression Of A Beach | See recession of a shoreline. [14] |
| 5507 | Sailing: Middle-Latitude | A method of converting departure into difference of longitude, or vice versa, when the true course is not 90° or 270°, by assuming that such a course is steered at the middle latitude. [14] |
| 5508 | Secondary Air Pollutants | Pollutants that form when a chemical reaction occurs between a primary air pollutant and some other component of air. Tropospheric ozone is a secondary air pollutant. [1] |
| 5509 | Sight (Or Sighting) Vane | See vane. [14] |
| 5510 | Single Beam Echo Sounder | (sbes) an echo sounder that transmits and receives a sound pulse providing a single spot depth, as opposed to a multi beam echo sounder. [14] |
| 5511 | Station Mark (Or Marker) | A buried mark-stone, a metal plug or disk, or any kind of permanent mark intended to provide a means of re-identifying main control stations. See surface mark and underground mark. [14] |
| 5512 | Stereographic Projection | See projection. [14] |
| 5513 | Subsurface Sound Channel | The submarine sound channel which is adjacent to the water surface. [14] |
| 5514 | Tape: Tension Correction | The correction applied to the nominal length of a tape to allow for a change in effective length because of its being used at a tension other than that for which its standard length is known. [14] |
| 5515 | Taut Wire Measuring Gear | An apparatus designed for measuring horizontal distances at sea. It is constructed so that a wire of small diameter, one end of which is anchored on the bottom, passes around a calibrated sheave as the ship steams along the route to be measured. [14] |
| 5516 | Tide(S): Quarter-Diurnal | The tide resulting from the distortion of the normal tide in shallow water with four high waters and four low waters during one day. See also tide(s): shallow water. [14] |
| 5517 | Tides: Mixed Semidiurnal | Semidiurnal tides with noticeable inequality in corresponding extremes. [14] |
| 5518 | Total Magnetic Intensity | The vector resultant of the intensity of the horizontal and vertical components of the earth's magnetic field at a specified point. [14] |
| 5519 | Trace (Of Precipitation) | An amount of precipitation less than 0.01 in. (0.025 cm). [1] |
| 5520 | Transverse Mercator Grid | The grid on a chart using the transverse Mercator projection. [14] |
| 5521 | Tropic Higher High Water | The higher high water of tropic tides. [14] |
| 5522 | Tropical Monsoon Climate | A tropical climate with a brief dry period of perhaps one or two months. [1] |
| 5523 | Vector Data Presentation | Method of representing image features digitally by points, lines and polygons given through their coordinates and appropriate code(s). [14] |
| 5524 | Very Low Frequency (Vlf) | See frequency: radio. [14] |
| 5525 | Wave: Transitional Water | A progressive gravity wave in water whose depth is less than 1/2 but more than 1/25 the wavelength. Often called shallow water wave. [14] |
| 5526 | Acoustic Line Of Position | See sonic line of position. [14] |
| 5527 | Aeronautical Ground Light | See light. [14] |
| 5528 | Age Of Diurnal Inequality | The time interval between the maximum semi-monthly north or south declination of the moon and the maximum effect of the declination upon the range of tide or the speed of the tidal current, this effect being manifested chiefly by an increase in the height or speed difference between the two high (low) waters or flood (ebb) currents during the day. The tides occurring at this time are called tropic tides. Also called diurnal age. [14] |
| 5529 | Astronomic(Al) Refraction | See refraction. [14] |
| 5530 | Base Course (Of A Vessel) | The true course between a vessel's point of departure and arrival. [14] |
| 5531 | Chart: Coast (Or Coastal) | A nautical chart intended for inshore coastwise navigation. [14] |
| 5532 | Circle Of Right Ascension | See hour circle. [14] |
| 5533 | Clamp (Or Clamping) Screw | A screw for holding in place a moving part of an instrument as during an observation or reading with a theodolite or sextant. [14] |
| 5534 | Coefficient Of Refraction | See refraction: coefficient of. [14] |
| 5535 | Contour (Or Contour Line) | A line connecting points of equal elevation or equal depth. See also form line, hachures, illuminated contours, index contours. [14] |
| 5536 | Datum Of Tide Predictions | The level from which the heights of tide are referenced in the tide tables. See also datum: chart. [14] |
| 5537 | Depression Of The Horizon | See dip. [14] |
| 5538 | Dispersion (Of Pollution) | The spreading out of atmospheric pollutants. [1] |
| 5539 | Dry (Or Dry Card) Compass | See compass. [14] |
| 5540 | Electronic Plotting Sheet | See plotting sheet. [14] |
| 5541 | Ellipticity Of An Ellipse | The ratio between the difference in length of the semi-axes of an ellipse and its semi-major axis. [14] |
| 5542 | Enhanced Group Call (Egc) | The system for broadcasting messages via the mobile satellite communications system operated by inmarsat. EGC is a part of the inmarsat-c system. [14] |
| 5543 | Error Of Magnetic Compass | The angle by which a compass direction differs from the true direction; the algebraic sum of variation and deviation. [14] |
| 5544 | Error Of Run (Micrometer) | The difference in seconds of arc, between the intended value of one turn of the micrometer screw and its actual value as determined by measuring the space between two adjacent graduation marks of the circle with the micrometer. Also called run of micrometer. [14] |
| 5545 | Establishment Of The Port | See establishment. [14] |
| 5546 | Extreme Water Level (Ewl) | Combination of design crest elevation, astronomical tide, and storm surge referenced to either lat or msl. [14] |
| 5547 | Final Great Circle Course | See course: great circle. [14] |
| 5548 | First Order Triangulation | See triangulation classification. [14] |
| 5549 | Fishery Conservation Zone | See fishing zone. [14] |
| 5550 | Frequency: Very Low (Vlf) | See frequency: radio. [14] |
| 5551 | Greenwich Mean Time (Gmt) | See time. [14] |
| 5552 | Halo: Large (Halo Of 46°) | Halo much less frequent and always less luminous than the small halo. It comprises a faintly luminous ring centered on the sun or moon and has an apparent radius of 46°. [14] |
| 5553 | Halo: Small (Halo Of 22°) | White, or mostly white, luminous ring of 22° radius with the luminary at its center. The small halo shows a faint red fringe on the inside and, in some rare cases, a violet fringe on the outside. The portion of the sky inside the ring is conspicuously darker than the rest of the sky. [14] |
| 5554 | Higher High Water (H.H.W) | The higher of two high waters occurring during a tidal day if the diurnal inequality prevails. [14] |
| 5555 | Higher Low Water Interval | See lunitidal interval. [14] |
| 5556 | Highest Astronomical Tide | The highest tidal level which can be predicted to occur under average meteorological conditions and under any combination of astronomical conditions. [14] |
| 5557 | Humid Continental Climate | A climate characterized by severe winters and mild to warm summers with adequate annual precipitation. Typically located over large continental areas in the northern hemisphere between about 40° and 70° latitude. [1] |
| 5558 | Humid Subtropical Climate | A climate characterized by hot muggy summers, cool to cold winters, and abundant precipitation throughout the year. [1] |
| 5559 | International (Int) Chart | A nautical chart with limits and scale in conformity with an internationally agreed scheme of such charts; carries the int number of that sheet; conforms to the chart specifications of the iho. [14] |
| 5560 | Isohaline (Or Isohalsine) | A line connecting points of equal salinity in the ocean. [14] |
| 5561 | Light (Or Lighted) Beacon | See beacon. [14] |
| 5562 | Light: Aerial Obstruction | Light marking an obstacle which constitutes a danger to air navigation. [14] |
| 5563 | Light: Fixed And Flashing | A rhythmic light in which a fixed light is combined with a flashing light of higher luminous intensity. [14] |
| 5564 | Longitude: Geographic(Al) | A general term, applying alike to astronomical and geodetic longitude. [14] |
| 5565 | Lower High Water (L.H.W.) | The lower of two high waters occurring during a tidal day if the diurnal inequality prevails. [14] |
| 5566 | Lower High Water Interval | See lunitidal interval. [14] |
| 5567 | Lubber (Or Lubber'S) Line | A reference line on any direction-indicating instrument, marking the reading which coincides with the heading. [14] |
| 5568 | Magnetic Annual Variation | The small systematic temporal variation in the earth's magnetic field which occurs after the trend for secular change has been removed from the average monthly values. Also referred to as annual variation. [14] |
| 5569 | Mandatory Routeing System | a routing system adopted by the international maritime organization, in accordance with the requirements of regulation v/10 of the 1974 solas convention, for mandatory use by all ships, certain categories of ships or ships carrying certain cargoes. [14] |
| 5570 | Meridian Distance: Double | The algebraic sum of the perpendicular distances from the two ends of any line of a traverse to the initial, or reference, meridian. [14] |
| 5571 | New Print Date (Of Chart) | In US Terminology, the date when a new print of a chart is issued which embodies changes or corrections of a relatively minor character. The new print date is added to the right of the edition date in the lower left-hand corner of the chart. [14] |
| 5572 | Obliquity Of The Ecliptic | The acute angle between the plane of the ecliptic and the plane of the celestial equator, about 23° 27'. [14] |
| 5573 | Ocean Acoustic Tomography | A method to determine the ocean structure based on precise measurements of transit time of acoustic waves between a net of transmitters and receivers. [14] |
| 5574 | Parallel Rulers (Or Rule) | An instrument for transferring a line parallel to itself. [14] |
| 5575 | Pelagic-Abyssal Sediments | Deep sea sediments that are free of terrestrial material except for a small proportion of very fine clay. [14] |
| 5576 | Photogrammetric Extension | See phototriangulation. [14] |
| 5577 | Photograph: Multiple Lens | A photograph made with a multiple lens camera. [14] |
| 5578 | Pingo-Like Features (Plf) | Small conical undersea features having the geomorphological appearance of pingos. [14] |
| 5579 | Plumb Line: Deflection Of | See deflection of the vertical. [14] |
| 5580 | Principal Vertical Circle | The vertical circle through the north and south points of the horizon, coinciding with the celestial meridian. [14] |
| 5581 | Reduction To The Meridian | The process of applying a correction to an altitude observed when a body is near the celestial meridian of the observer, to find the altitude at meridian transit. See altitude: ex-meridian. [14] |
| 5582 | Refraction Of Water Waves | The process by which the direction of a wave moving in shallow water at an angle to the contours is changed. That part of the wave advancing in shallower water moves more slowly than the other part still advancing in deeper water, causing the wave crest to bend toward alignment with the underwater contours. Also called wave refraction. The bending of wave crests by currents. [14] |
| 5583 | Route (Or Routeing) Chart | See chart. [14] |
| 5584 | Saturation Vapor Pressure | The maximum amount of water vapor necessary to keep moist air in equilibrium with a surface of pure water or ice. It represents the maximum amount of water vapor that the air can hold at any given temperature and pressure. (see equilibrium vapor pressure.) [1] |
| 5585 | Sea Bottom Sediment Chart | See chart: sea bottom sediment. [14] |
| 5586 | Separation Zone (Or Line) | A zone or line separating the traffic lanes in which ships are proceeding in opposite, or nearly opposite directions; or separating a traffic lane from the adjacent sea area; or separating traffic lanes designated for particular classes of ships proceeding in the same direction. [14] |
| 5587 | Shallow Water Corrections | Quantities to be applied to a tide prediction to correct for the quarter diurnal tides. [14] |
| 5588 | Shutter: Between-The-Lens | A shutter located between the lens elements of a camera; usually consisting of thin metal leaves which open and close or revolve to make the exposure. [14] |
| 5589 | Single Buoy Mooring (Sbm) | A large mooring buoy used by tankers to load and unload in port approaches or in offshore oil and gas fields. [14] |
| 5590 | Southern Oscillation (So) | The reversal of surface air pressure at opposite ends of the tropical pacific ocean that occur during major el niño events. [1] |
| 5591 | Stabilization: Gyroscopic | See gyroscopic stabilization. [14] |
| 5592 | Starred Lines Of Sounding | Lines of sounding which are 'starred' round a rock or islet. [14] |
| 5593 | Systems Of Sounding Lines | The predetermined lines that the survey platform is to follow for the best development of the depth contours in an area. [14] |
| 5594 | Tape: Catenary Correction | See tape: sag correction. [14] |
| 5595 | Telescope: Photo Zenithal | An instrument designed to take photos of stars culminating close to the zenith of a station in order to determine the position of the station with high accuracy. [14] |
| 5596 | Tension Correction (Tape) | See tape: tension correction. [14] |
| 5597 | Third Order Triangulation | See triangulation classification. [14] |
| 5598 | Transit: Broken Telescope | A precise astronomic transit or theodolite in which the light passing through the objective lens is reflected through a right angle by a prism placed in the horizontal axis. This hollow axis is continued beyond the supports, and the eyepiece is fitted at one end. [14] |
| 5599 | Underwater Photogrammetry | See photogrammetry. [14] |
| 5600 | Very High Frequency (Vhf) | See frequency: radio. [14] |
| 5601 | Visual Display Unit (Vdu) | See display. [14] |
| 5602 | Zero Crossing Wave Period | TZ ; The inverse of the average number of times that the ocean level moves up across the mean water level per second. [22] |
| 5603 | Age Of Parallax Inequality | The time interval between perigee of the moon and the maximum effect of parallax upon the range of tide or the speed of the tidal current. [14] |
| 5604 | Alignment Correction(Tape) | See tape: alignment correction. [14] |
| 5605 | Atomic Time: International | The time reference coordinate established by the bureau international de l'heure on the basis of atomic clocks. [14] |
| 5606 | Automatic Floating Station | A buoy equipped with instruments automatically recording oceanographic and meteorological data. Also called automatic buoy. [14] |
| 5607 | Beacon: Light (Or Lighted) | A beacon from which a light is exhibited. [14] |
| 5608 | Catenary Correction (Tape) | See tape: sag correction. [14] |
| 5609 | Celestial Line Of Position | A line of position determined by means of one celestial body. [14] |
| 5610 | Chart: Route (Or Routeing) | A chart showing routes between various places, usually with distances indicated. [14] |
| 5611 | Chart: Sea Bottom Sediment | A chart primarily showing information on the types and characteristics of sea bottom. [14] |
| 5612 | Clear Air Turbulence (Cat) | Turbulence encountered by aircraft flying through cloudless skies. Thermals, wind shear, and jet streams can each be a factor in producing cat. [1] |
| 5613 | Compass: Dry (Or Dry Card) | A compass without a liquid-filled bowl, particularly a magnetic compass having a very light compass card. Such a magnetic compass is seldom used in modern practice. See compass: liquid. [14] |
| 5614 | Compression (Of The Earth) | See flattening of the earth. [14] |
| 5615 | Continental Polar Air Mass | An air mass characterized by low temperatures and dry air. Not as cold as arctic air masses. [1] |
| 5616 | Cruising Radius (Or Range) | The distance a craft can travel at a given speed without refueling. [14] |
| 5617 | Daily Range Of Temperature | The difference between the maximum and minimum temperatures for any given day. [1] |
| 5618 | Draftsman (Or Draughtsman) | A person who makes drawings. [14] |
| 5619 | Electronic Data Processing | In a computer, data processing performed largely or exclusively on electronic equipment. [14] |
| 5620 | Enhanced Fujita (Ef) Scale | A modification of the original fujita scale that describes tornado intensity by observing damage caused by the tornado. [1] |
| 5621 | Equinoctial Spring Tide(S) | See tide. [14] |
| 5622 | Frequency: Very High (Vhf) | See frequency: radio. [14] |
| 5623 | Geographic(Al) Coordinates | See coordinates. [14] |
| 5624 | Higher High Water Interval | See lunitidal interval. [14] |
| 5625 | Intensity Of Magnetization | See magnetization. [14] |
| 5626 | Isothermal (Or Isothermic) | (Adj.). Of or relating to equal temperature. [14] |
| 5627 | Light: Aeronautical Ground | Any light specially provided as an aid to navigation, other than a light displayed on an aircraft. [14] |
| 5628 | Lighter Aboard Ship (Lash) | A cargo carrying system using specially built ships and lighters. Cargoes are loaded into lash lighters which are towed to a lash ship where they are embarked. At their destination the lash lighters are disembarked and towed away to their unloading berths. Special berths or anchorages are sometimes designated for lash ships. [14] |
| 5629 | Local Frequency Oscillator | An oscillator used to derive an intermediate frequency by beating with the signal carrying frequency in superheterodyne reception. [14] |
| 5630 | Local Magnetic Disturbance | An anomaly of the magnetic field of the earth, extending over a relatively small area, due to local magnetic influences. Also called local attraction or magnetic anomaly. [14] |
| 5631 | Magnetometric Zero Balance | A magnetic observatory instrument used for accurate measurement of the vertical component of the earth's magnetic field. [14] |
| 5632 | Maritime Tropical Air Mass | An air mass characterized by high temperatures and high humidity. [1] |
| 5633 | Metacentre (Or Metacenter) | That point in a floating body at which a vertical line drawn through its center of buoyancy when it is upright meets the vertical line drawn through its center of buoyancy when it is tipped. Centre of gravity of the unsubmerged part of a floating body; for stable equilibrium the meta center must be above the center of gravity. [14] |
| 5634 | Mountain And Valley Breeze | A local wind system of a mountain valley that blows downhill (mountain breeze) at night and uphill (valley breeze) during the day. [1] |
| 5635 | Occluded Front (Occlusion) | A complex frontal system that ideally forms when a cold front overtakes a warm front. When the air behind the front is colder than the air ahead of it, the front is called a cold occlusion. When the air behind the front is milder than the air ahead of it, it is called a warm occlusion. [1] |
| 5636 | Ocean Station Vessel (Osv) | Ship assigned to operate at the location of an ocean weather station. Also called weather ship. [14] |
| 5637 | Orientation Of Plane Table | Placing the plane table in such a position that every line drawn on the survey sheet from the point which represents the position of the table on the ground to any other point on the sheet, is parallel to the corresponding line in nature. [14] |
| 5638 | Parallel Motion Protractor | See protractor. [14] |
| 5639 | Plotting Sheet: Electronic | A chart showing time difference or phase difference curves of a circular or a hyperbolic navigational system. These lattice lines are used to accurately position the data collected during hydrographic or oceanographic surveys. [14] |
| 5640 | Potable Water Intake (Pwi) | A structure designed for the intake of drinking water. The intake is usually elevated above the bottom, supported and protected by a debris screening structure (crib), a separately charted feature. [14] |
| 5641 | Price-Gurley Current Meter | A battery powered electromechanical current meter which measures current speed only. [14] |
| 5642 | Radar Surveillance Station | A radar station established for traffic surveillance. [14] |
| 5643 | Radiant Energy (Radiation) | Energy propagated in the form of electromagnetic waves. These waves do not need molecules to propagate them, and in a vacuum they travel at nearly 300,000 km per sec (186,000 mi per sec). [1] |
| 5644 | Radio Navigational Warning | see navigational warning. [14] |
| 5645 | Refraction: Coefficient Of | The ratio of the angle of refraction at the point of observation to the angle at the center of the earth subtended by the arc connecting the point of observation and the observed point. [14] |
| 5646 | Second Order Triangulation | See triangulation classification. [14] |
| 5647 | Single Point Mooring (Spm) | A mooring structure used by tankers to load and unload in port approaches or in offshore oil and gas fields. The size of the structure can vary between a large mooring buoy and a manned floating structure. [14] |
| 5648 | Speed Of Relative Movement | See relative motion. [14] |
| 5649 | Super High Frequency (Shf) | See frequency: radio. [14] |
| 5650 | Supplemental Control Point | A photo image point for which an elevation or a horizontal position, or both, is to be, or has been determined. See also control point. [14] |
| 5651 | Tape: Alignment Correction | A correction applied to the measured length of a line to allow for the tape not being held exactly in a vertical plane containing the line. [14] |
| 5652 | Terrestrial Magnetic Field | See geomagnetic field. [14] |
| 5653 | Terrestrial Photogrammetry | See photogrammetry. [14] |
| 5654 | Tide (Or Tidal) Prediction | The mathematical process by which the times and heights of the tide are determined in advance from the harmonic constituents at a place. See harmonic analysis of tide. [14] |
| 5655 | Ultra High Frequency (Uhf) | See frequency: radio. [14] |
| 5656 | Ultraviolet (Uv) Radiation | Electromagnetic radiation with wavelengths longer than x-rays but shorter than visible light. [1] |
| 5657 | Underwater Sound Projector | A transducer used to produce sound in water. The conversion from electrical energy to sound is achieved through the use of either the piezoelectric or magneto strictive effect. See magnetostriction and piezoelectricity. [14] |
| 5658 | Universal Drafting Machine | See protractor: parallel motion. [14] |
| 5659 | Unsurveyed Clearance Depth | The estimated depth over an unsurveyed wreck or obstruction over which the exact depth is unknown but which is considered to have a safe clearance to the depth shown. [14] |
| 5660 | Visibility: Meteorological | The greatest distance at which a black object of suitable dimensions can be seen and recognized against the horizon sky, or, in the case of night observations, could be seen and recognized if the general illumination were raised to the normal daylight level. [14] |
| 5661 | Analogue Forecasting Method | A forecast made by comparison of past large-scale synoptic weather patterns that resemble a given (usually current) situation in its essential characteristics. [1] |
| 5662 | Annual Range Of Temperature | The difference between the warmest and coldest months at any given location. [1] |
| 5663 | Bathyscaphe (Or Bathyscaph) | A free, manned vehicle for exploring the deep ocean. [14] |
| 5664 | Continental Arctic Air Mass | An air mass characterized by extremely low temperatures and very dry air. [1] |
| 5665 | Coordinates: Geographic(Al) | A system of spherical coordinates for defining the positions of points on the earth. [14] |
| 5666 | Data Base Management System | A set of software for creating, maintaining and accessing the data of a data base. [14] |
| 5667 | Deep Scattering Layer (Dsl) | See phantom bottom. [14] |
| 5668 | Digital Terrain Model (Dtm) | A model representing the terrain surface by a collection of digital data, mainly coordinates in three dimensions, x, y, and z, and a digitally defined method to interpolate arbitrary terrain heights in between the stored values. Not to be confused with digital cartographic model which may also contain digital data representing terrain, but in a form suitable for the drawing of a particular kind of map. [14] |
| 5669 | Dilution Of Precision (Dop) | A parameter relating the precision of the position (and/or an unknown auxiliary) provided by a positioning system to that of the "observed quantities" directly measured by the system. Dop is a measure of the influence of the geometry of loci on the precision of position fixing. Dop is frequently used with a qualifying term such as geometric (gdop), horizontal (hdop), vertical (vdop) etc. To indicate that dop is related to all or some unknown quantities. [14] |
| 5670 | Electronic Line Of Position | A line of position established by means of electronic equipment. [14] |
| 5671 | Ellipticity Of The Spheroid | See flattening of the earth. [14] |
| 5672 | Error Of Closure Of Horizon | The amount by which the sum of a series of adjacent measured horizontal angels around a point fails to equal exactly 360°. [14] |
| 5673 | Exterior Perspective Centre | See perspective center. [14] |
| 5674 | Frequency: Super High (Shf) | See frequency: radio. [14] |
| 5675 | Frequency: Ultra High (Uhf) | See frequency: radio. [14] |
| 5676 | Horizon: Visible (Or Local) | See horizon: apparent. [14] |
| 5677 | Horizontal Force Instrument | See vibrating needle. [14] |
| 5678 | Hyperbolic Line Of Position | A line of position in the shape of a hyperbola, determined by measuring the difference in distance to two fixed points. [14] |
| 5679 | Incineration Areas (At Sea) | An offshore area officially designated as suitable for the burning of chemical waste by specially equipped ships. [14] |
| 5680 | Interior Perspective Centre | See perspective center. [14] |
| 5681 | International Nautical Mile | A unit of length equal to 1,852 meters. This value was approved by the international hydrographic conference of 1929 and has been adopted by nearly all maritime states. [14] |
| 5682 | Inverse Mercator Projection | See projection. [14] |
| 5683 | Light: Sector (Or Sectored) | A light presenting different appearances (in particular, different colors) over various parts of the horizon of interest to maritime navigation. [14] |
| 5684 | Liquid-In-Glass Thermometer | An instrument for measuring temperature. The most common is liquid-in-glass, which has a sealed glass tube attached to a glass bulb filled with liquid. See thermometer. [1] |
| 5685 | Longwaves In The Westerlies | A wave in the upper level of the westerlies characterized by a long length (thousands of kilometers) and significant amplitude. Also called Rossby waves. [1] |
| 5686 | Magnetic Temporal Variation | Any change in the earth's magnetic field which is a function of time. Also referred to as temporal variation. [14] |
| 5687 | Magnetostriction Transducer | See transducer. [14] |
| 5688 | Meteorological Observations | See observation. [14] |
| 5689 | Negative Feedback Mechanism | A process whereby an initial change in an atmospheric process will tend to either reinforce the process (positive feedback) or weaken the process (negative feedback). See feedback mechanism. [1] |
| 5690 | Niño/Southern Oscillation)" | A condition in the tropical pacific whereby the reversal of surface air pressure at opposite ends of the pacific ocean induces westerly winds, a strengthening of the equatorial countercurrent, and extensive ocean warming. [1] |
| 5691 | Oblique Plotting Instrument | An instrument (usually monocular) for plotting from oblique photographs. [14] |
| 5692 | Photogrammetry: Terrestrial | Photogrammetry utilizing terrestrial photographs. [14] |
| 5693 | Photographic Interpretation | The examination of photographic images for the purpose of identifying objects and deducing their significance. [14] |
| 5694 | Positive Feedback Mechanism | A process whereby an initial change in an atmospheric process will tend to either reinforce the process (positive feedback) or weaken the process (negative feedback). See feedback mechanism. [1] |
| 5695 | Precession Of The Equinoxes | The conical motion of the earth's axis about the vertical to the plane of the ecliptic, caused by the attractive force of the sun, moon, and other planets on the equatorial protuberance of the earth. [14] |
| 5696 | Protractor: Parallel Motion | An instrument consisting essentially of a protractor and one or more arms attached to a parallel motion device, so that the movement of the arms is everywhere parallel. The protractor can be rotated and set at any position so that it can be oriented to a chart. Also called universal drafting machine. [14] |
| 5697 | Roberts Radio Current Meter | An electro-mechanical current meter which measures current speed and direction. This meter can be suspended below an anchored buoy or ship which is equipped with a radio transmitter that transmits the current measurements to a ship or shore based monitor station. [14] |
| 5698 | Sensitivity Of Spirit Level | See sensibility of spirit level. [14] |
| 5699 | Sextant Altitude Correction | Any of several corrections applied to a sextant altitude in the process of converting it to true altitude. [14] |
| 5700 | Shelf Edge (Or Shelf Break) | The line along which there is a marked increase of slope at the seaward margin of a continental (or island) shelf. [14] |
| 5701 | Ship-To-Shore Triangulation | See triangulation. [14] |
| 5702 | Tachymeter (Or Tacheometer) | A surveying instrument designed for use in the rapid determination of distance, direction, and difference of elevation from a single observation, using a short base which may be an integral part of the instrument. [14] |
| 5703 | Tide(S): Equinoctial Spring | Those tides occurring near the equinoxes when the full or new moon and the sun have little or low declination and spring tides of greater range than the average occur, particularly if the moon is also nearly in perigee. [14] |
| 5704 | Tropic Low Water Inequality | See diurnal inequality. [14] |
| 5705 | Upper Limit Of Navigability | The character of a river will, at some point along its length, change from navigable to non navigable. Very often that point will be at a major fall or rapids, or other place where there is a marked decrease in the navigable capacity of the river. The upper limit will therefore often be the same point traditionally recognized as the head of navigation, but may, under some of the tests described above, be at some point yet farther upstream. [14] |
| 5706 | Absolutely Stable Atmosphere | An atmospheric condition that exists when the environmental lapse rate is less than the moist adiabatic rate. This results in a lifted parcel of air being colder than the air around it. [1] |
| 5707 | Adiabatic Temperature Change | Rise or fall of temperature due to compression or expansion without gain or loss of heat to the surroundings. [14] |
| 5708 | Base Extension Triangulation | (British terminology). A part of a triangulation net starting with a measured base and expanding that relatively short distance to a larger distance comparable to the average length of the triangulation sides. Called base net in US Terminology. [14] |
| 5709 | Cautionary (Or Caution) Note | Information calling special attention to some fact, usually a danger area shown on a chart, or other publication. [14] |
| 5710 | Centigrade Temperature Scale | See celsius temperature scale. [14] |
| 5711 | Circular Radiobeacon Station | A radio station which needs not necessarily be manned, the emissions of which, radiated around the horizon, enable its bearing to be determined by means of the radio direction finder of a ship. [14] |
| 5712 | Clearance: Overhead Pipeline | Minimum vertical or horizontal space available for passage. [14] |
| 5713 | Convergence Of The Meridians | The angular drawing together of the geographic meridians in passing from the equator to the poles. The difference between the two angles formed by the intersection of a great circle with two meridians. The difference between the reciprocal bearings of two points. At any point of a cartographic projection, the angle between the meridian, as represented on the plane of the projection and grid in use, and the grid north line. [14] |
| 5714 | Datum For Sounding Reduction | See datum: sounding. [14] |
| 5715 | Deflection Of The Plumb Line | See deflection of the vertical. [14] |
| 5716 | Fahrenheit Temperature Scale | A temperature scale defined by the relationship t°f = 1.8 t°c + 32; developed by Gabriel D. Fahrenheit (1686-1736), german physicist. [14] |
| 5717 | Interferometric Echo Sounder | A type of swath(e) sounding system in which the equipment emits a timed pulse of sound that is narrow in the fore-aft direction and wide in the across-track direction. The system samples the reflected sound hundreds or even thousands of times for each emission. For each sample, the phase difference of the reflected sound arriving at two (or more) receivers located a known distance apart is measured and used to compute the acoustic angle of arrival. Also, the time difference between the emission and reception for each sample is converted to a range. Geometry is then used to convert each range and angle to depths and also to position these depths within the swath(e) on the sea floor. [14] |
| 5718 | Köppen Classification System | A system for classifying climates developed by W. Köppen that is based mainly on annual and monthly averages of temperature and precipitation. [1] |
| 5719 | Light: Continuous Very Quick | A light showing 80 to 159, usually either 100 or 120, flashes per minute. [14] |
| 5720 | Mineral Development Platform | See platform: mineral development. [14] |
| 5721 | Napier'S (Or Napier) Diagram | A diagram on which compass deviation is plotted for various headings, and the points connected by a smooth curve, permitting a ready conversion of deviations from compass to magnetic headings, or vice versa. [14] |
| 5722 | Navigable Area Surveys (Nas) | Navigable area surveys are basic hydrographic surveys with restricted area coverage. The coverage is reduced by omitting requirements for: 1. Development of the 0 foot depth curve and foul, nearshore areas not considered navigable; 2. Complete field edit of the survey area. Navigable area surveys may also be restricted to the main navigable channel or corridor. [14] |
| 5723 | Observation Spot (Or Pillar) | A position ashore determined from celestial observations. [14] |
| 5724 | Observation(S): Astronomical | Observations of celestial bodies, with appropriate instruments. In navigation, the measurement of altitude and azimuth of celestial bodies. [14] |
| 5725 | Optical Pumping Magnetometer | See magnetometer. [14] |
| 5726 | Orientation: Photogrammetric | The recreation of natural terrain features at a miniature scale by the optical projection of overlapping photographs. The model is formed when all corresponding light rays from the two projectors intersect in space. See also orientation: absolute, orientation: basal, orientation: exterior, orientation: interior. [14] |
| 5727 | Projection: Inverse Mercator | The name given to the transverse Mercator projection when the latter is extended right over both poles. It is used for air charts of polar areas. [14] |
| 5728 | Radio Acoustic Sound Ranging | See radio acoustic ranging. [14] |
| 5729 | Rotating Radiobeacon Station | A special type of radio beacon station emitting a beam of waves to which a uniform turning movement is given, the bearing of the station being determined by means of an ordinary listening receiver and a stopwatch. Also referred to as rotating loop radio beacon. [14] |
| 5730 | Rubidium Vapour Magnetometer | See magnetometer. [14] |
| 5731 | Savonius Rotor Current Meter | A low-threshold current speed sensor composed of two cylindrical vanes disposed to form an s-shaped rotor responsive to a wide spectrum of horizontal flow components. [14] |
| 5732 | Scale Of Hydrographic Survey | That scale at which the positions of the soundings in the area are plotted on the hydrographic survey sheet. Suitable survey scales are selected in each case in accordance with the nature of the survey and the average depths prevailing in the area. [14] |
| 5733 | Tach Stave (Levelling Staff) | A staff with a length of about 2m with subdivisions. It is used in combination with a levelling instrument or theodolite. [14] |
| 5734 | Tape: Temperature Correction | The quantity applied to the nominal length of a tape to allow for a change in its effective length because of its being used at a temperature other than that for which its standard length is given. [14] |
| 5735 | Temperature-Salinity Diagram | The plot of temperature versus salinity data of a water column. The result is a diagram which identifies the water masses within the column, the column's stability, and indicates the ïƒt value, and allows an estimate of the accuracy of the temperature and salinity measurements. [14] |
| 5736 | Transducer: Magnetostriction | A transducer that depends for its operation on the interaction between the magnetization and the deformation of a material having magneto strictive properties. [14] |
| 5737 | Traverse: Open (Or Open End) | A traverse which starts from a station of known or adopted position but does not end upon such a station. Also called hanging traverse. [14] |
| 5738 | Triangulation Classification | The classifying of triangulations into first-order, second-order, and third-order triangulation, according to the error of closure of triangles. In first-order work, the average closure is not in excess of 1 second; in second order work, it does not exceed 3 seconds; and in third-order work, it does not exceed 5 seconds. For the basic first-order work, the computed length through the network must agree with the measured base within 1 part in 50 000, as a minimum, and average about 1 in 75 000, or better. [14] |
| 5739 | Triangulation: Ship-To-Shore | A method of triangulation involving simultaneous observations from three shore stations on a target carried by a ship offshore of the middle station. The middle station must be visible from each of the two end stations. [14] |
| 5740 | Tropic High Water Inequality | See diurnal inequality. [14] |
| 5741 | Tropical Wet-And-Dry Climate | A tropical climate poleward of the tropical wet climate where a distinct dry season occurs, often lasting for two months or more. [1] |
| 5742 | Vector Airborne Magnetometer | See magnetometer. [14] |
| 5743 | Vessel Traffic Service (Vts) | Any service implemented by a relevant authority primarily designed to improve safety and efficiency of traffic flow and the protection of the environment. It may range from simple information messages to extensive organization of the traffic involving national or regional schemes. [14] |
| 5744 | Astronomic(Al) Observation(S) | See observation. [14] |
| 5745 | Azimuth (Of A Celestial Body) | The angle between the observer's meridian and the vertical circle through the body, measured in the plane of the horizon. There is no universally accepted manner of reckoning the azimuths. Quadrantal, half-circle, and whole-circle methods are being used. In the latter, the azimuth is measured preferably clockwise from north. See also azimuth angle. [14] |
| 5746 | Bubble: Spirit (Or Sensitive) | See level: spirit. [14] |
| 5747 | Central Processing Unit (Cpu) | In computers in general the unit that comprises the arithmetic logic unit and the control unit. [14] |
| 5748 | Coherent Electromagnetic Wave | See wave: electromagnetic. [14] |
| 5749 | Collision-Coalescence Process | The process of producing precipitation by liquid particles (cloud droplets and raindrops) colliding and joining (coalescing). [1] |
| 5750 | Conic (Or Conical) Projection | see projection. [14] |
| 5751 | Continental (Or Island) Slope | The zone of declivity from the outer edge of a continental (or island) shelf into greater depth. See slope. [14] |
| 5752 | Continental Tropical Air Mass | An air mass characterized by high temperatures and low humidity. [1] |
| 5753 | Contrail (Condensation Trail) | A cloudlike streamer frequently seen forming behind aircraft flying in clear, cold, humid air. [1] |
| 5754 | Coring Instrument (Or Device) | See corer. [14] |
| 5755 | Electronic Navigation Station | See station. [14] |
| 5756 | Eulerian Current Observations | A method to monitor the current at a fixed point by means of current meters. [14] |
| 5757 | Fish Aggregating Device (Fad) | See fish haven. [14] |
| 5758 | Foot Of The Continental Slope | The point of maximum change of gradient at the base of the continental slope. [14] |
| 5759 | Frost (Also Called Hoarfrost) | A covering of ice produced by deposition on exposed surfaces when the air temperature falls below the frost point. [1] |
| 5760 | Geographic Information System | A computer-based system for handling and integrating data from a variety of sources which is directly or indirectly spatially referenced to earth. [14] |
| 5761 | Horizon System Of Coordinates | a set of celestial coordinates based on the celestial horizon as the primary great circle; usually altitude and azimuth or azimuth angle. [14] |
| 5762 | Hydrographic Data Acquisition | All on-site measurements to collect hydrographic data. [14] |
| 5763 | Isoclinal (Or Isoclinic) Line | A line connecting points of equal magnetic dip. Also called isoclinal. [14] |
| 5764 | Levelling Instrument: Y Level | A levelling instrument having the telescope, with attached spirit level, supported in y's. The telescope can be rotated about its longitudinal axis in the y's and it can be lifted and reversed, end for end. [14] |
| 5765 | Light: Continuous Ultra Quick | A light showing 160 or more, usually 240 to 300, flashes per minute. [14] |
| 5766 | Light: Interrupted Very Quick | A light in which the very rapid alterations of light and darkness are interrupted at regular intervals by eclipses of long duration. [14] |
| 5767 | Long Baseline Acoustic System | An underwater position fixing system which consists of an array of seabed transponders with baselines of several kilometers. [14] |
| 5768 | Low Water Quadrature (L.W.Q.) | The average low water interval when the moon is at quadrature. [14] |
| 5769 | Magnetometer: Optical Pumping | A highly sensitive magnetometer which employs a metastable helium or alkali metal absorption cell whose atoms absorb maximum energy from an infrared beam when a frequency modulation oscil-lator is tuned to its resonant frequency. The resonant frequency is proportional to the strength of the earth's magnetic field. [14] |
| 5770 | Magnetometer: Rubidium Vapour | An optical pumping magnetometer which employs a rubidium vapor absorption cell. [14] |
| 5771 | Magnetometer: Vector Airborne | A flux-gate magnetometer which measures the intensity and direction of the earth's magnetic field from an aircraft. [14] |
| 5772 | Phase Of A Navigational Light | A visually discrete part of a light signal. It is bounded by changes between darkness and light (e.g., An occultation or flash), or between different colors, or between distinctly different luminous intensities, and it may be further discriminated by its duration. [14] |
| 5773 | Plan Position Indicator (Ppi) | A cathode-ray scope on which signals appear in correct relation to each other, so that the scope face presents a map like representation of the area about the transmitter, the direction of a target being represented by the direction of its echo from a center and range by its distance from that center. [14] |
| 5774 | Plane Rectangular Coordinates | see coordinates. [14] |
| 5775 | Platform: Mineral Development | A platform used in the exploitation of minerals. [14] |
| 5776 | Polar Orthographic Projection | see projection. [14] |
| 5777 | Pressure Gradient Force (Pgf) | The force due to differences in pressure within the atmosphere that causes air to move and, hence, the wind to blow. It is directly proportional to the pressure gradient. [1] |
| 5778 | Profiling: Continuous Seismic | Determination of the subsoil strata and geological structure by use of sound sources which emit acoustic pulses to penetrate the seabed. Travel time between emission of pulses and reception is usually measured in a towed streamer. [14] |
| 5779 | Shortwave (In The Atmosphere) | A small wave that moves around long waves in the same direction as the air flow in the middle and upper troposphere. Shortwaves are also called shortwave troughs. [1] |
| 5780 | Standard Atmospheric Pressure | A pressure of 1013.25 millibars (mb), 29.92 inches of mercury (hg), 760 millimeters (mm) of mercury, 14.7 pounds per square inch (lb/in.2), or 1013.25 hectopascals (HPa). [1] |
| 5781 | Surveying (Or Mapping) Camera | See camera. [14] |
| 5782 | Synodic (Or Synodical) Period | The interval of time between any planetary configuration of a celestial body, with respect to the sun, and the next successive same configuration of that body, as from inferior conjunction to inferior conjunction. [14] |
| 5783 | Temperature Correction (Tape) | See tape: temperature correction. [14] |
| 5784 | Absolute Stereoscopic Parallax | See parallax. [14] |
| 5785 | Absolutely Unstable Atmosphere | An atmospheric condition that exists when the environmental lapse rate is greater than the dry adiabatic rate. This results in a lifted parcel of air being warmer than the air around it. [1] |
| 5786 | Calibration: Indirect Position | The calibration of a positioning system using positions of the survey vessel at different locations which were determined independently of the positioning system. True distances can be derived from these positions and by comparison with the data rendered by the positioning system, calibration values can be deduced. [14] |
| 5787 | Camera: Surveying (Or Mapping) | A camera specially designed for the production of photographs to be used in surveying. The prefix 'mapping' or 'surveying' indicates that the camera is equipped with means for maintaining and indicating the interior orientation of the photographs with sufficient accuracy for surveying purposes. A mapping camera may be an aerial mapping camera or a terrestrial mapping camera. [14] |
| 5788 | Coordinates: Plane Rectangular | A system of coordinates in a horizontal plane used to describe the positions of points with respect to an arbitrary origin by means of two distances perpendicular to each other. The two reference lines at right angles to each other passing through the origin are called the coordinate axes. The distances parallel to the true (or arbitrarily assigned) north-south axis are called the ordinates, or the y-coordinates. The distances parallel to the true (or arbitrarily assigned) east-west axis are called the abscissae, or the x-coordinates. The north and east directions are usually taken as positive, and the south and west directions are usually taken as negative. Also referred to as plane coordinates. [14] |
| 5789 | Digitization (Or Digitisation) | The process of converting analog data to digital data. [14] |
| 5790 | Direction Of Relative Movement | See relative motion. [14] |
| 5791 | Dry-Summer Subtropical Climate | A climate characterized by mild, wet winters and warm to hot, dry summers. Typically located between 30 and 45 degrees latitude on the western side of continents. Also called Mediterranean climate. [1] |
| 5792 | Ecliptic System Of Coordinates | A set of celestial coordinates based on the ecliptic as the primary great circle; celestial latitude and celestial longitude. [14] |
| 5793 | Equatorial Horizontal Parallax | See parallax. [14] |
| 5794 | Extremely High Frequency (Ehf) | See frequency: radio. [14] |
| 5795 | High Water Quadrature (H.W.Q.) | The average high water interval when the moon is at quadrature. See lunitidal interval. [14] |
| 5796 | Ice-Crystal (Bergeron) Process | A process that produces precipitation. The process involves tiny ice crystals in a supercooled cloud growing larger at the expense of the surrounding liquid droplets. Also called the bergeron process. [1] |
| 5797 | Initial Great Circle Direction | initial great circle course. [14] |
| 5798 | International Ice Patrol (Iip) | Activities of the international ice patrol include collecting and analyzing data concerning iceberg detection and movement. The patrol's mission is to provide the latest information on iceberg positions and computer prediction of the extent of the iceberg danger zone to North Atlantic mariners. Areas of study include iceberg detection, drift and deterioration, surface object drift, and currents in the grand banks region. [14] |
| 5799 | Light: Interrupted Ultra Quick | A light in which the ultra quick flashes (160 or more per minute) are interrupted at regular intervals by eclipses of long duration. [14] |
| 5800 | Light: Rotating (Or Revolving) | a light which has one or more beams which rotate. [14] |
| 5801 | Marginal Information (Or Data) | The notations printed in the margins or borders of mosaics, plans, or maps. [14] |
| 5802 | Maritime Boundary Delimitation | The process of establishing line(s) of delimitation at sea. [14] |
| 5803 | Microwave Distance Measurement | any method of electromagnetic distance measurement based on a comparison of radio microwave signals. [14] |
| 5804 | Observation(S): Meteorological | Evaluation or measurement of one or more meteorological elements. [14] |
| 5805 | Outlooks (Seasonal And 90-Day) | An overview or projection of how certain weather elements (such as temperature and precipitation) might compare with average weather conditions. [1] |
| 5806 | Projection: Conic (Or Conical) | a projection produced by projecting the geographic meridians and parallels onto a cone which is tangent to (or intersects) the surface of a sphere, and then developing the cone into a plane. [14] |
| 5807 | Projection: Polar Orthographic | an orthographic projection having the plane of the projection perpendicular to the axis of rotation of the earth (parallel with the plane of the equator); in this projection, the geographic meridians are straight lines. [14] |
| 5808 | Proton Precession Magnetometer | see magnetometer: nuclear precession. [14] |
| 5809 | Quartz Horizontal Magnetometer | see magnetometer. [14] |
| 5810 | Rock Which Covers And Uncovers | A rock of small area (pinnacle) that covers and uncovers at various states of the tide. [14] |
| 5811 | Short Baseline Acoustic System | An underwater acoustic position fixing system comprising a minimum of three hydrophones on the hull of a surface vessel. Three ranges are measured to a beacon either mounted on the seabed or a submersible to obtain a three-dimensional position fix. [14] |
| 5812 | Slotted-Template Triangulation | in photogrammetry, a graphical radial triangulation using slotted templates. [14] |
| 5813 | Station: Electronic Navigation | a station emitting radio signals which are used in electronic navigational systems. [14] |
| 5814 | Stereographic Polar Projection | see projection: stereographic. [14] |
| 5815 | Strip Film (Or Stripping Film) | A film which has the emulsion coated on an extremely thin membrane which is in turn supported on a normal ‘thickness film base. The emulsion and the membrane can be stripped (separated) from the base after exposure and processing. The thin image so obtained can be mounted face down on a new support for lateral image reversal or used for combining with, or inserting in, other image elements. [14] |
| 5816 | Synthetic Aperture Radar (Sar) | A radar with a synthetic aperture antenna which is composed of a large number of elementary transducing elements. The signals are electronically combined into a resulting signal equivalent to that of a single antenna of a given aperture in a given direction. [14] |
| 5817 | Transverse Mercator Projection | see projection. [14] |
| 5818 | Vertical Dilution Of Precision | See dilution of precision. [14] |
| 5819 | Wind Vector (Or Wind Velocity) | vector drawn in the sense and direction of the wind and of length proportional to wind speed. [14] |
| 5820 | Calibration: Indirect Variation | The calibration of a positioning system by obtaining redundant observations so that calibration values can be deduced mathematically from the discrepancies between uncalibrated values at different locations. [14] |
| 5821 | Direction Method Of Observation | A method of observing angular relationships wherein the graduated circle is held in a fixed position, and the directions of the various signals are observed around the horizon. Thus, directions are pointing whereby angles are found by the differences in direction. [14] |
| 5822 | Electromagnetic Position Fixing | Any process or technique of fixing which employs the properties of electromagnetic waves. [14] |
| 5823 | Estimated Time Of Arrival (Eta) | The predicted time of reaching a destination or waypoint. [14] |
| 5824 | Frequency: Extremely High (Ehf) | See frequency: radio. [14] |
| 5825 | Geometric Dilution Of Precision | See dilution of precision. [14] |
| 5826 | Global Positioning System (Gps) | a satellite-based navigation system designed to provide highly accurate position and velocity information in three dimensions and precise time and time interval on a global basis continuously. Gps is operated by the united states government. Gps to which differential corrections have been applied is known as differential gps (DGPS). See also global navigation satellite system. [14] |
| 5827 | Hydrographic Survey Examination | Review of a hydrographic survey that is directed toward evaluating compliance with, and the adequacy of, standards, rather than a careful examination of the data and their quality. The survey is carefully examined for adequacy with respect to data acquisition and conformance with applicable standards and project instructions. In addition, the overall condition of the records and the descriptive report are examined. The digital data representing the survey is plotted and subjected to a cursory examination (spot check) to ensure that digital data standards are being adhered to. The examination of the survey data is limited only to that necessary to evaluate the acquisition and processing procedures. [14] |
| 5828 | Lagrangian Current Observations | The method for observing ocean currents by tracking the movement of drifting floats, buoys, tracers etc. The rate and direction of movement of a particular sample of water is measured. This is the opposite to eularian current observations where the movement of water past a fixed point is measured by a current meter. [14] |
| 5829 | Light: Composite Group-Flashing | A flashing light in which a sequence of groups of one or more flashes, which are specified in number, is regularly repeated, and the groups comprise different numbers of flashes. [14] |
| 5830 | Light: Fixed And Group-Flashing | A fixed light varied at regular intervals by a group of two or more flashes of greater brilliance. This character is being gradually suppressed. [14] |
| 5831 | Magnetometer: Proton Precession | see magnetometer: nuclear precession. [14] |
| 5832 | Magnetometer: Quartz Horizontal | a magnetometer in which the torque exerted on a suspended magnet by the earth's horizontal magnetic field is balanced against the torque exerted by the quartz suspension fibre when twisted through 360°. [14] |
| 5833 | Mean Low Water Neaps (M.L.W.N.) | the average height of the low waters of neap tides. Also called neap low water. [14] |
| 5834 | Mean Lower Low Water (M.L.L.W.) | the average height of the lower low waters at a place over a 19-year period. [14] |
| 5835 | Nuclear Precession Magnetometer | see magnetometer. [14] |
| 5836 | Obliquity (Of The Earth'S Axis) | The tilt of the earth's axis. It represents the angle from the perpendicular to the plane of the earth's orbit. [1] |
| 5837 | Parallax: Absolute Stereoscopic | In photogrammetry, considering a pair of aerial photographs of equal principal distance, the algebraic difference of the distances of the two images from their respective photograph nadirs, measured in a horizontal plane and parallel to the air base. Also called horizontal parallax, linear parallax, or x-parallax. [14] |
| 5838 | Parallax: Equatorial Horizontal | horizontal parallax as observed at the equator, as it attains its maximum value. [14] |
| 5839 | Projection: Stereographic Polar | See projection: stereographic. [14] |
| 5840 | Remotely Operated Vehicle (Rov) | An unmanned submersible craft which can be used either for observation purposes or to perform hydrographic surveys, or for working purposes. Also called "remotely controlled vehicle (RCV)". [14] |
| 5841 | Sensibility Of Magnetic Compass | The ability of a magnetic compass card to align itself with the magnetic meridian after deflection. [14] |
| 5842 | Source Regions (For Air Masses) | Regions where air masses originate and acquire their properties of temperature and moisture. [1] |
| 5843 | Transhipment Or Lightening Area | An area designated for transfer of cargo from one vessel to another sometimes in order to reduce a vessel ™s draught. Also called cargo transfer area or cargo transshipment area. [14] |
| 5844 | Azimuthal Equidistant Projection | See projection. [14] |
| 5845 | Calibration: Direct Simultaneous | The calibration of a positioning system at the same time when the distances used for calibration are measured using another system or instrument of superior accuracy. [14] |
| 5846 | Common (Or Vulgar) Establishment | See establishment. [14] |
| 5847 | Compensation Of Magnetic Compass | The process of neutralizing or reducing to a minimum the magnetic effects the vessel itself exerts on a magnetic compass. It is based on the principle that the magnetic effect of the iron and steel of the vessel can be counterbalanced by means of magnets and soft iron placed near the compass. Also called compass adjustment, compass compensation, or magnetic compensation. [14] |
| 5848 | Coordinated Universal Time (Utc) | See universal time coordinated. [14] |
| 5849 | Cross Section Lines Of Soundings | Sounding lines run in a survey perpendicular to the flow of a stream and from bank to bank in a river. [14] |
| 5850 | Direction (Or Directional) Light | See light. [14] |
| 5851 | High Water Lunitidal Interval (H | .i.). See lunitidal interval. [14] |
| 5852 | Light: Composite Group-Occulting | An occulting light in which a sequence of groups of one or more eclipses, which are specified in number, is regularly repeated, and the groups comprise different numbers of eclipses. [14] |
| 5853 | Magnetometer: Nuclear Precession | a magnetometer that utilizes the precessional characteristics of hydrogen nuclei when in an ambient magnetic field. Also known as proton precession magnetometer. [14] |
| 5854 | Mean High Water Neaps (M.H.W.N.) | The average height of the high waters of neap tides. Also called neap high water. [14] |
| 5855 | North Atlantic Oscillation (Nao) | A reversal of atmospheric pressure over the atlantic ocean that influences the weather over Europe and over eastern North America. [1] |
| 5856 | Period (Of A Navigational Light) | The time taken to exhibit one complete sequence of intervals of light and darkness. [14] |
| 5857 | Repetition Method Of Observation | a method of observing horizontal angles by which the observations of each angle are completed separately. See theodolite: repeating. [14] |
| 5858 | Stereographic Horizon Projection | See projection: stereographic. [14] |
| 5859 | Stereoscopic Plotting Instrument | An instrument for compiling a map or obtaining spatial solutions by observation of stereoscopic images formed by stereoscopic pairs. See compilation. [14] |
| 5860 | System International (Si System) | System of metric measures consisting of seven basic units which are metre, kilogram, second, ampere, kelvin, mole and candela. [14] |
| 5861 | Thermometer: Protected Reversing | A reversing thermometer enclosed in a heavy glass case to protect it from hydrostatic pressure. [14] |
| 5862 | Universal Time Coordinated (Utc) | The time scale that is available from most broadcast time signals. It differs from international atomic time by an integral number of seconds. UTC is maintained within 1 second of ut1 by the introduction of 1-second steps (leap seconds) when necessary, normally at the end of December. Dut1, an approximation to the difference ut1 minus UTC, is transmitted in code on broadcast time signals. [14] |
| 5863 | Vulgar (Or Common) Establishment | see establishment. [14] |
| 5864 | Azimuthal Orthomorphic Projection | See projection: stereographic. [14] |
| 5865 | Barometer: Mercurial (Or Mercury) | A barometer in which atmospheric pressure is balanced against the pressure exerted by a column of mercury. [14] |
| 5866 | Chemical Weathering- Co2 Feedback | A negative feedback in earth's climate system. As chemical weathering of rocks increases, co2 is removed from the atmosphere more quickly, which in turn weakens the greenhouse effect, causing the atmosphere to cool. Thus, an increase in global chemical weathering tends to lower atmospheric temperatures. [1] |
| 5867 | Conditionally Unstable Atmosphere | An atmospheric condition that exists when the environmental lapse rate is less than the dry adiabatic rate but greater than the moist adiabatic rate. Also called conditional instability. [1] |
| 5868 | Dew Point (Dew-Point Temperature) | The temperature to which air must be cooled (at constant pressure and constant water vapor content) for saturation to occur. [1] |
| 5869 | Digital Imagery Processing System | A system which processes images which are stored in digital form. [14] |
| 5870 | Direction Of The Force Of Gravity | See gravity: direction of. [14] |
| 5871 | Estimated Time Of Departure (Etd) | The predicted time of leaving a place. [14] |
| 5872 | Levelling Instrument: Dumpy Level | A levelling instrument which has its telescope permanently attached to the levelling base, either rigidly or by a hinge that can be manipulated by a micrometer screw. [14] |
| 5873 | Light: Direction (Or Directional) | a light illuminating a sector of very narrow angle and intended to mark a direction to be followed. [14] |
| 5874 | Light: Interrupted Quick-Flashing | A quick light in which the sequence of flashes is interrupted by regularly repeated eclipses of constant and long duration. [14] |
| 5875 | Maritime Safety Information (Msi) | Navigational and meteorological warnings, meteorological forecasts, distress alerts and other urgent safety related messages broadcast to ships. [14] |
| 5876 | Mean Diurnal Low Water Inequality | See diurnal inequality. [14] |
| 5877 | Mean Higher High Water (M.H.H.W.) | The average height or higher high waters at a place over a 19-year period. [14] |
| 5878 | Mean Low Water Springs (M.L.W.S.) | The average height of the low waters of spring tides. This level is used as a tidal datum in some areas. Also called spring low water. [14] |
| 5879 | Navstar Global Positioning System | A satellite navigation system. [14] |
| 5880 | Pacific Decadal Oscillation (Pdo) | A reversal in ocean surface temperatures that occurs every 20 to 30 years over the northern pacific ocean. [1] |
| 5881 | Projection: Azimuthal Equidistant | an azimuthal projection on which straight lines radiating from the center or pole of projection represent great circles in their true azimuths from the center, and lengths along these lines are of exact scale. This projection is neither equal area nor conformal. [14] |
| 5882 | Punched (Or Punch) Card Equipment | A system whose principal feature is that numbers are recorded on cards by means of holes punched in successive columns of a card, the row of the card indicating the digit. [14] |
| 5883 | Radiative Equilibrium Temperature | The temperature achieved when an object, behaving as a blackbody, is absorbing and emitting radiation at equal rates. [1] |
| 5884 | Reference Spheroid (Or Ellipsoid) | A theoretical figure whose dimensions closely approach the dimensions of the geoid. The exact dimensions are determined by various considerations of the section of the earth's surface considered. The spheroids of bessel, clarke, delambre, everest, hayford, helbert and others have been adopted as reference spheroids in geodetic work by different countries. Also called spheroid of reference, or ellipsoid of reference. See also spheroid: oblate. [14] |
| 5885 | Rescue Co-Ordination Centre (Rcc) | A unit responsible for promoting efficient organization of search and rescue services and for coordinating the conduct of search and rescue operations within a search and rescue region. Also called maritime rescue co-ordination center (MRCC) and joint rescue co-ordination center (JRCC). [14] |
| 5886 | Simultaneous Comparison Of Depths | The comparison of echo sounding depths with simultaneous direct vertical measurements of depth. Simultaneous comparisons are periodically made to determine the instrumental error of echo sounders. [14] |
| 5887 | Unprotected Reversing Thermometer | See thermometer. [14] |
| 5888 | Volatile Organic Compounds (Vocs) | A class of organic compounds that are released into the atmosphere from sources such as motor vehicles, paints, and solvents. Vocs (which include hydrocarbons) contribute to the production of secondary pollutants, such as ozone. [1] |
| 5889 | Bearing: Mercatorial (Or Mercator) | See bearing: rhumb. [14] |
| 5890 | Covers And Uncovers (Or Discovers) | Expression intended to indicate an area of a reef or other projection from the bottom of a body of water which periodically extends above and is submerged below the surface. Also referred to as dries or uncovers. [14] |
| 5891 | Direction Of Movement Of The Waves | Direction from which the waves arrive at a fixed point. [14] |
| 5892 | Freezing Rain And Freezing Drizzle | Rain or drizzle that falls in liquid form and then freezes upon striking a cold object or ground. Both can produce a coating of ice on objects, which is called glaze. [1] |
| 5893 | Galvanoplasty (Or Galvanoplastics) | the process of coating things with metal by means of electrolysis. [14] |
| 5894 | Inclination Of The Horizontal Axis | The vertical angle between the horizontal axis of a surveying or astronomical instrument and the plane of the horizon. [14] |
| 5895 | Instrumental (Or Instrument) Error | See error. [14] |
| 5896 | Lambert Conformal Conic Projection | See projection. [14] |
| 5897 | Mean Diurnal High Water Inequality | See diurnal inequality. [14] |
| 5898 | Mean High Water Springs (M.H.W.S.) | The average height of the high waters of spring tides. Also called spring high water. [14] |
| 5899 | Meridional Orthographic Projection | See projection. [14] |
| 5900 | Mesoscale Convective Complex (Mcc) | A large organized convective weather system comprised of a number of individual thunderstorms. The size of an mcc can be 1000 times larger than an individual ordinary thunderstorm. [1] |
| 5901 | Meteorological Optical Range Table | A table from the international visibility code which gives the code number of meteorological visibility and the meteorological visibility for several weather conditions such as thin fog (code no. 4-meteorological visibility 1/2-1 nautical mile); clear (code no. 7-meteorological visibility 5 1/2-11 nautical miles). [14] |
| 5902 | Numerical Weather Prediction (Nwp) | Forecasting the weather based upon the solutions of mathematical equations by high-speed computers. [1] |
| 5903 | Polar Front Jet Stream (Polar Jet) | The jet stream that is associated with the polar front in middle and high latitudes. It is usually located at altitudes between 9 and 12 km. [1] |
| 5904 | Projection: Azimuthal Orthomorphic | see projection: stereographic. [14] |
| 5905 | Side-Looking Airborne Radar (Slar) | A radar system using a stabilized antenna orientated at right angles to the aircraft flight path. [14] |
| 5906 | Temperature Correction (Levelling) | That correction which is applied to an observed difference of elevation to correct for the error introduced when the temperature at which the levelling rods are used in the field is different from the temperature at which they were standardized. [14] |
| 5907 | Thermometer: Unprotected Reversing | A reversing thermometer which is not protected against hydrostatic pressure. Used in conjunction with protected reversing thermometers to determine thermometric depth. [14] |
| 5908 | Air Pressure (Atmospheric Pressure) | The pressure exerted by the mass of air above a given point, usually expressed in millibars (mb), inches of mercury (hg) or in hectopascals (HPa). [1] |
| 5909 | Air Pressure (Atmospheric Pressure) | The pressure exerted by the mass of air above a given point, usually expressed in millibars (mb), inches of mercury (hg) or in hectopascals (HPa). [1] |
| 5910 | Automatic Radar Plotting Aid (Arpa) | A system wherein radar targets are automatically acquired and tracked and collision situations computer assessed and warnings given. [14] |
| 5911 | Centimetre-Gram-Second (Cgs) System | The system of physical units in which the fundamental units of length, mass and time are the centimeter, gram and second, respectively. [14] |
| 5912 | Cold Advection (Cold Air Advection) | The transport of cold air by the wind from a region of lower temperatures to a region of higher temperature. [1] |
| 5913 | Eccentricity (Of The Earth'S Orbit) | The deviation of the earth's orbit from elliptical to nearly circular. [1] |
| 5914 | Electronic Navigational Chart (Enc) | 1. An electronic navigational chart is a subset of the electronic chart data base held on the vessel. It contains information on features useful for navigation such as coastline, obstructions, beacons etc. 2. The digital data base that is intended to be used in conjunction with ECDIS. Standardized as to content, structure and format the enc may contain supplementary nautical information useful for safe navigation. The enc is a subset of the master data base of chart information. [14] |
| 5915 | Error: Instrumental (Or Instrument) | A systematic error resulting from imperfections in, or faulty adjustment of, instruments or devices used. [14] |
| 5916 | Hydrographic Airborne Laser Sounder | A system for measuring the depth of water by sending a laser pulse from an aircraft and recording the time difference between the sea surface and the bottom reflection. [14] |
| 5917 | Hydrographic Data Processing System | A system for verification, selection, and calculation of hydrographic survey data. [14] |
| 5918 | Hypsographic (Or Hypsometric) Curve | A curve used to indicate the proportion of the area of the surface at various elevations above or depths below a given datum. [14] |
| 5919 | Levelling Instrument: Tilting Level | A levelling instrument in which the final levelling of the instrument is obtained by small controlled amounts of rotation of the telescope about a horizontal axis. [14] |
| 5920 | Orientation Of Surveying Instrument | Placing the instrument in such position that the horizontal circle reads 0° when the line of collimation is parallel to the direction it had at an earlier (initial) position of the instrument, or to a standard line of reference. If the line of reference is a meridian, the circle will show azimuths referred to that meridian. [14] |
| 5921 | Projection: Azimuthal (Or Zenithal) | A projection on which the azimuths or directions of all lines radiating from a central point or pole are the same as the azimuths or directions of the corresponding lines on the sphere. [14] |
| 5922 | Projection: Lambert Conformal Conic | A conformal projection of the conical type, on which all geographic meridians are represented by straight lines which meet in a common point outside the limits of the map, and the geographic parallels are represented by a series of arcs of circles having this common point for a center. Meridians and parallels intersect at right angles, and angles on the earth are correctly represented on the projection. This projection may have one or two standard parallels along which the scale is held exact. [14] |
| 5923 | Projection: Meridional Orthographic | An orthographic projection having the plane of the projection parallel to the plane of some selected meridian; in this projection, the geographic parallels and the central meridian are straight lines, the outer meridian is a full circle, and the other meridians are arcs of ellipses. [14] |
| 5924 | Sensitivity Of Electronic Equipment | The ability of electronic equipment to amplify a signal, measured by the minimum strength of signal input capable of causing a desired value of output. The lower the input signal for a given output, the higher the sensitivity. [14] |
| 5925 | Stereographic Meridional Projection | See projection: stereographic. [14] |
| 5926 | Epicentre (Or Epicenter, Epicentrum) | The point of the earth's surface directly above the focus of an earthquake. [14] |
| 5927 | Intensity: Luminous (In A Direction) | Quotient of the luminous flux emitted by a source, or by an element of a source in an infinitesimal cone containing the given direction, by the solid angle of that cone. [14] |
| 5928 | International Ellipsoid Of Reference | A reference ellipsoid having the following approximate dimensions: semimajor axis 6378388.0 meters; semi minor axis 6356911.9 meters; and the flattening or ellipticity 1/297. See also Hayford's spheroid and flattening of the earth. [14] |
| 5929 | International Geophysical Year (Igy) | By international agreement, a period during which greatly increased observation of world-wide geophysical phenomena is undertaken through the cooperation effort of participating nations. [14] |
| 5930 | International Map Of The World (Imw) | The map of the world on the scale of 1/1 000 000 which was planned under the auspices of the international geographical union and carried out by very many of the countries of the world. [14] |
| 5931 | Irradiance (At A Point Of A Surface) | Quotient of the flux of radiation incident on an infinitesimal element of surface containing the point under consideration, by the area of that element. [14] |
| 5932 | Low Water Lunitidal Interval (L.W.I) | Low water interval. See lunitidal interval. [14] |
| 5933 | Projection: Stereographic Horizontal | See projection: stereographic. [14] |
| 5934 | Projection: Stereographic Meridional | See projection: stereographic. [14] |
| 5935 | Super-Short Baseline Acoustic System | A variation of the short baseline system with three sensors incorporated in a single transducer. [14] |
| 5936 | Astronomy: Nautical (Or Navigational) | Astronomy as applied to navigation. [14] |
| 5937 | Automatic Identification System (Ais) | an automatic communication and identification system intended to improve the safety of navigation by assisting the efficient operation of vessel traffic services (VTS), ship reporting, and ship-to-ship and ship-to-shore operations. [14] |
| 5938 | Ellipsoid Of Revolution (Or Rotation) | A simple mathematical surface which best approximates the shape of the earth. It is the surface generated by an ellipse revolving about one of its axes. See also spheroid: oblate, spheroid: prolate and reference spheroid. [14] |
| 5939 | General Circulation Of The Atmosphere | Large-scale atmospheric motions over the entire earth. [1] |
| 5940 | Instrumental (Or Instrument) Parallax | See parallax. [14] |
| 5941 | Intertropical Convergence Zone (Itcz) | The boundary zone separating the northeast trade winds of the northern hemisphere from the southeast trade winds of the southern hemisphere. [1] |
| 5942 | Irradiation (At A Point Of A Surface) | Product of an irradiance and its duration. [14] |
| 5943 | Magnetic Daily (Or Diurnal) Variation | Oscillations of the earth's magnetic field which have a periodicity of about a day and that depend to a close approximation only on local time and geographic latitude. [14] |
| 5944 | Parhelia Associated With The 22° Halo | Photometeor of the halo family, consisting of two luminous iridescent spots which appear on the parhelic circle close to the small halo. [14] |
| 5945 | Parhelia Associated With The 46° Halo | Photometeor of the halo family consisting of two luminous, iridescent spots which appear on the parhelic circle close to the large halo. [14] |
| 5946 | Position Dilution Of Precision (Pdop) | See dilution of precision. [14] |
| 5947 | Supercooled Cloud (Or Cloud Droplets) | A cloud composed of liquid droplets at temperatures below 0°c (32°f). When the cloud is on the ground it is called supercooled fog or cold fog. [1] |
| 5948 | Conditional Distribution (Probability) | Statistical distribution (probability) of the occurrence of a variable a, given that other variables b,c,… have certain assigned values. [14] |
| 5949 | Direction Of Traffic Flow: Established | A traffic flow pattern indicating the directional movement of traffic as established within a traffic separation scheme. [14] |
| 5950 | Direction Of Traffic Flow: Recommended | A traffic flow pattern indicating a recommended directional movement of traffic where it is impractical or unnecessary to adopt an established direction of traffic flow. [14] |
| 5951 | Illumination (At A Point Of A Surface) | Quotient of the luminous flux incident on an infinitesimal element of the surface containing the point under consideration, by the area of that element. [14] |
| 5952 | Insulated (Or Insulating) Water Bottle | See water bottle. [14] |
| 5953 | International Geographical Union (Igu) | Founded in 1922 to promote the study of geographical problems, igu initiates and coordinates research and provides for scientific discussion and publication. [14] |
| 5954 | Navigational (Or Navigation) Satellite | An artificial earth-orbiting satellite designed for navigational purposes. [14] |
| 5955 | Parallax: Instrumental (Or Instrument) | That change which may result from the position in which an observer stands with respect to the fiducial marks on an instrument (personal parallax); or by the imperfect adjustment of the optics of the instrument (optical parallax). [14] |
| 5956 | Particularly Sensitive Sea Area (Pssa) | An area which needs special protection through action by the IMO because of its significance for recognized ecological or socio-economic or scientific reasons and which may be vulnerable to damage by maritime activities. A PSSA is a type of environmentally sensitive sea area (ESSA). [14] |
| 5957 | Spectral Moment or nth Spectral Moment | Integral over frequency of the spectral density function multiplied by the nth power of the frequency, either expressed in hertz (cycles per second) or expressed in circular frequency (radians/second). [15] |
| 5958 | Survey (Or Surveying) Ship (Or Vessel) | A vessel or platform (e.g., Aircraft) specially equipped for carrying out topographic, hydrographic and/or oceanographic survey. [14] |
| 5959 | Warm Advection (Or Warm Air Advection) | The transport of warm air by the wind from a region of higher temperatures to a region of lower temperatures. [1] |
| 5960 | Water Vapor?Greenhouse Effect Feedback | A positive feedback whereby increasing surface air temperatures cause an increase in the evaporation of water from the oceans. Increasing concentrations of atmospheric water vapor enhance the greenhouse effect, which causes the surface air temperature to rise even more. [1] |
| 5961 | Analytical (Or Analytic) Photogrammetry | See under photogrammetry. [14] |
| 5962 | Celestial Equator System Of Coordinates | A set of celestial coordinates based on the celestial equator as the primary great circle. Usually declination, right ascension and hour angle, or sidereal hour angle. Also called equinoctial system of coordinates. [14] |
| 5963 | Echo Sounding Instrument (Or Apparatus) | See echo sounder. [14] |
| 5964 | Horizontal Dilution Of Precision (Hdop) | See dilution of precision. [14] |
| 5965 | Instrumental (Or Instrument) Correction | That correction due to instrumental error. [14] |
| 5966 | International Geological Congress (Igc) | Congresses held by IUGS. [14] |
| 5967 | International Hydrographic Bureau (Ihb) | Founded in 1921 in the Principality of Monaco, to establish a close and permanent association among the hydrographic offices of its member states; since 1970 the headquarters of the international hydrographic organization. [14] |
| 5968 | Large Automatic Navigation Buoy (Lanby) | A large buoy designed to take the place of a lightship where construction of an offshore light station is not feasible. See also buoy: super. [14] |
| 5969 | Satellite: Navigational (Or Navigation) | See navigational (or navigation) satellite. [14] |
| 5970 | Water Bottle: Insulated (Or Insulating) | A water bottle specially designed for measuring temperatures and collecting water samples at moderate depths. This type of water bottle is insulated to maintain the temperature constant while being brought to the surface. [14] |
| 5971 | World Meteorological Organization (Wmo) | Promotes international cooperation in the field of meteorology. [14] |
| 5972 | Azimuth: Astronomic(Al) Determination Of | The determination of the azimuth of a line or base line by astronomical observations. [14] |
| 5973 | Composite Electronic Navigational System | One contrived in such a way that the position is determined by lines of different types, for instance, by a lattice of circles and a lattice of hyperbolae. [14] |
| 5974 | Food And Agricultural Organization (Fao) | Aims at the improvement of the standard of living, especially of the rural population of third world countries, by increasing the production and improving the distribution of agricultural products. [14] |
| 5975 | Photogrammetry: Analytical (Or Analytic) | Photogrammetry in which solutions are obtained by mathematical means. [14] |
| 5976 | Universal Transverse Mercator (Utm) Grid | See grid. [14] |
| 5977 | Environmentally Sensitive Sea Area (Essa) | a generic term which is used to describe a wide range of areas, considered sensitive for a variety of environmental reasons. [14] |
| 5978 | Global Navigation Satellite System (Gnss) | the standard generic term for satellite navigation systems ("satnav") that provide autonomous geo-spatial positioning with global coverage. As of 2011, GPS and GLONASS are the only operational systems with new systems (for example the e.u's galileo and china's beidou) expected by 2020. [14] |
| 5979 | High Water Full And Change (H.W.F And C.) | See establishment. [14] |
| 5980 | International Maritime Organization (Imo) | A specialized agency of the united nations whose primary role is to develop and maintain a comprehensive regulatory framework for shipping. Its remit includes safety, environmental concerns, legal matters, technical co-operation, maritime security and the efficiency of shipping. Imo was formerly called the inter-governmental maritime consultative organization (IMCO). [14] |
| 5981 | Levelling Instrument: Self-Aligning Level | A level in which a sensitive prism element inside the telescope acts on the principle of the pendulum and ensures that the line of sight is horizontal, even if the axis of the telescope is several minutes out of the horizontal. [14] |
| 5982 | Low Water Full And Change (L.W.F. And C.) | The average interval of time between the transit (upper or lower) of the full or new moon and the next low water. [14] |
| 5983 | Mean Lower Low Water Springs (M.L.L.W.S.) | The average height of lower low water springs at a place. [14] |
| 5984 | Projection: Universal Transverse Mercator | See grid: Universal Transverse Mercator (UTM). [14] |
| 5985 | Straits Used For International Navigation | Geographically, a narrow passage between two land masses or islands or group of islands connecting two larger sea areas. [14] |
| 5986 | Electromagnetic Distance Measurement (Edm) | Any process or technique of distance measurement which depends on a comparison of signals by electromagnetic means. [14] |
| 5987 | International Association Of Geodesy (Iag) | One association of IUGG. [14] |
| 5988 | Electro-Optical Distance Measurement (Eodm) | Any method of electromagnetic distance measurement based on a comparison of light signals. [14] |
| 5989 | International Federation Of Surveyors (Fig) | Brings together the leading national associations to exchange views of general interest to the profession and organizes the liaison between the various affiliated associations. [14] |
| 5990 | International Scientific Radio Union (Isru) | Promotes and organizes international cooperative research in radio science. [14] |
| 5991 | Radio Direction Finding (Or Finder) Station | A radio station intended to determine only the direction of other stations by means of transmission from the latter. [14] |
| 5992 | United Nations Development Programme (Undp) | An un agency which registers organizations and institutions located in developing countries which have the capacity for cooperative technical activities with organizations in other developing nations. The subject matter includes education and training courses, research and technological development activities, consulting and expert services, and scientific and technical information and used primarily by institutions and governments in developing countries. [14] |
| 5993 | Character (Or Characteristics) Of The Bottom | See bottom: nature of. [14] |
| 5994 | International Cartographic Association (Ica) | Advances the study of cartographic problems; instigates cartographic research involving cooperation between nations. [14] |
| 5995 | International Telecommunications Union (Itu) | Maintains and extends international cooperation for the improvement and rational use of telecommunications. [14] |
| 5996 | Mean Low Water Lunitidal Interval (M.L.W.I.) | See lunitidal interval. [14] |
| 5997 | Precession (Of The Earth'S Axis Of Rotation) | The wobble of the earth's axis of rotation that traces out the path of a cone over a period of about 23,000 years. [1] |
| 5998 | Sensibility (Or Sensitivity) Of Spirit Level | The accuracy and precision which a spirit level is capable of producing. Sensibility depends on the radius of curvature of its longitudinal section; the longer the radius, the more sensitive the level. [14] |
| 5999 | Directional (Or Directed) Radiobeacon Station | A special type of radio beacon station the emissions of which are intended to provide a definite track for guidance. [14] |
| 6000 | Electronic Distance-Measuring Equipment (Edm) | Devices that measure the phase difference between transmitted and returned (i.e., Reflected or retransmitted) electromagnetic waves, of known frequency and speed, or the round-trip transit time of a pulsed signal, from which distance is computed. A wide range of such equipment is available for surveying and navigational use. Also called distance measuring equipment (DME). [14] |
| 6001 | International Hydrographic Organization (Iho) | Coordinates the activities of national hydrographic offices; promotes standards and provides advice to developing countries in the fields of hydrographic surveying and production of nautical charts and publications. [14] |
| 6002 | Marginal Distribution or Marginal Probability | Statistical distribution (probability) of the occurrence of a variable A that is obtained by integrating over all values of the other variables B, C, … NOTE The marginal probability of A for all values of B, C, … is written as P(A). The concept is applicable to metocean parameters, as well as to actions and action effects. EXAMPLE When considering wave conditions, A can be the individual crest elevation for all mean zero-crossing periods B and all significant wave heights C, occurring at a particular site. [15] |
| 6003 | Mean High Water Lunitidal Interval (M.H.W.I.) | See lunitidal interval. [14] |
| 6004 | Computer-Assisted (Computer-Aided) Cartography | A system which is used to perform specific cartographic function by means of computer hardware and software which aids humans to make decisions and/or perform their functions. Because of the graphic nature of cartography, such a system always contains, or makes use of, a computer graphics system. [14] |
| 6005 | Transverse Cylindrical Orthomorphic Projection | See projection: transverse Mercator. [14] |
| 6006 | General Bathymetric Chart Of The Oceans (Gebco) | A global series of small-scale bathymetric charts. Edited through international cooperation by IHO and IOC. [14] |
| 6007 | Projection: Transverse Cylindrical Orthomorphic | See projection: transverse Mercator. [14] |
| 6008 | Time: Greenwich Mean (Gmt) (Or Greenwich Civil) | Mean solar time at the Greenwich meridian. See universal time (ut). [14] |
| 6009 | World Wide Navigational Warning Service (Wwnws) | A service established for the purpose of coordinating the transmissions of radio navigational warnings in geographical areas using coastal and satellite communication services. [14] |
| 6010 | Intergovernmental Oceanographic Commission (Ioc) | Established within UNESCO to promote the scientific investigation of the oceans through the concerted action of member states. [14] |
| 6011 | Vertical Intensity Of The Earth'S Magnetic Field | The strength of the vertical component of the earth's magnetic field. [14] |
| 6012 | International Council Of Scientific Unions (Icsu) | Coordinates and facilitates activities of international scientific unions in the field of exact and natural sciences; maintains relations with the specialized and related agencies of the un. [14] |
| 6013 | International Union Of Geological Sciences (Iugs) | Contributes to the advancement of investigations relating to the study of the earth. [14] |
| 6014 | Luminance (At A Point Of Surface, In A Direction) | Quotient of the luminous intensity, in a given direction, of an infinitesimal element of the surface containing the point under consideration, by the orthogonally projected area of the element on a plane perpendicular to the given direction. [14] |
| 6015 | Scientific Committee On Antarctic Research (Scar) | A committee established by ICSU to promote and coordinate Antarctic research. [14] |
| 6016 | Global Maritime Distress And Safety System (Gmdss) | The gmdss is a global communications service based upon automated systems, both satellites based and terrestrial, to provide distress alerting and promulgation of maritime safety information for mariners. [14] |
| 6017 | Horizontal Intensity Of The Earth'S Magnetic Field | The strength of the horizontal component of the earth's magnetic field. [14] |
| 6018 | International Bureau Of Weights And Measures (Ibwm) | Establishment of international standards and of measurement scales of physical sizes; determination of fundamental physical constants. [14] |
| 6019 | International Indian Ocean Expedition (Iioe Or Ioe) | An international expedition between 1959 and 1965 under the general coordination of the IOC. [14] |
| 6020 | International Union Of Geodesy And Geophysics (Iugg) | Promotes the study of all problems relating to the configuration and physics of the earth, its oceans and atmosphere; comprises a number of international associations. [14] |
| 6021 | Electronic Chart Display And Information System (Ecdis) | The navigation information system which is considered the legal equivalent of the nautical chart, displaying selected information from an electronic navigation chart (enc) integrated with data from positional and, optionally, other sensors. [14] |
| 6022 | International Association For Hydraulic Research (Iahr) | Stimulates and promotes hydraulic research, both basic and applied, in all its aspects. [14] |
| 6023 | International Union Of Pure And Applied Physics (Iupap) | creates and encourages international cooperation in physics; secures international agreement on symbols, units, nomenclature, and standards. [14] |
| 6024 | Pan American Institute Of Geography And History (Paigh) | develops, coordinates, and disseminates geographical, cartographic, historical, geophysical and related scientific studies. [14] |
| 6025 | International Association Of Scientific Hydrology (Iash) | Promotes and develops the study of hydrology; initiates, facilitates and coordinates research on such hydrological problems requiring international cooperation. [14] |
| 6026 | Federation Of Astronomical And Geophysical Services (Fags) | Facilitates and promotes the collection of observations, information and statistics in the field of astronomical and geophysical sciences. The international time bureau is one of the services. [14] |
| 6027 | International Association Of Lighthouse Authorities (Iala) | Association of authorities responsible for the provision or maintenance of lighthouses and other aids to marine navigation. [14] |
| 6028 | International Council For The Exploration Of The Sea (Ices) | Promotes research and investigations for the study of the sea, particularly programs related to living resources. [14] |
| 6029 | United Nations Conference On Trade And Development (Unctad) | Helps to restructure patterns of international trade in order to enable developing countries to play their part in world commerce. [14] |
| 6030 | Organization For Economic Cooperation And Development (Oecd) | Member states promote economic growth, employment, and improved standards of living for a sound and harmonious development of world economy. [14] |
| 6031 | International Association Of Geomagnetism And Aeronomy (Iaga) | Promotes international coordination of efforts to further the sciences of geomagnetism and aeronomy. [14] |
| 6032 | Ordinary Cell Thunderstorm (Also Called Air-Mass Thunderstorm) | A thunderstorm produced by local convection within a conditionally unstable air mass. It often forms in a region of low wind shear and does not reach the intensity of a severe thunderstorm. [1] |
| 6033 | Spectral Density Function or Energy Density Function or Spectrum | Measure of the variance associated with a time-varying variable per unit frequency band and per unit directional sector NOTE 1 Spectrum is a shorthand expression for the full and formal name of spectral density function or energy density function. NOTE 2 The spectral density function is the variance (the mean square) of the time-varying variable concerned in each frequency band and directional sector. Therefore, the spectrum is in general written with two arguments: one for the frequency variable and one for a direction variable. NOTE 3 Within this document the concept of a spectrum applies to waves, wind turbulence and action effects (responses) that are caused by waves or wind turbulence. For waves, the spectrum is a measure of the energy traversing a given space. [15] |
| 6034 | International Association Of Theoretical And Applied Limnology (Ial) | Furthers the progress of theoretical and applied limnology by holding congresses, by publishing the proceedings of the congresses, and by providing a sound foundation of methods and techniques of limnological investigations. [14] |
| 6035 | Permanent International Association Of Navigation Congresses (Pianc) | Fosters progress of inland and maritime waterways, of ports and of coastal areas by research and information exchange. [14] |
| 6036 | International Association For The Physical Sciences Of The Ocean (Iapso) | Promotes the study of scientific problems relating to the ocean and interactions at its boundaries. [14] |
| 6037 | International Association Of Meteorology And Atmospheric Physics (Iamap) | promotes meteorological research and investigation including all aspects of atmospheric physics, particularly in those fields which require international cooperation. [14] |
| 6038 | International Cooperative Investigations Of The Tropical Atlantic (Icita) | an international expedition coordinated by the IOC. [14] |
| 6039 | United Nations Educational, Scientific, And Cultural Organization (Unesco) | Organized in 1945 to promote collaboration among nations in education, science, and culture; UNESCO is the parent agency for the intergovernmental oceanographic commission. [14] |
| 6040 | International Association Of Seismology And Physics Of The Earth'S Interior (Iaspei) | Develops the study of seismology and physics of the earth's interior in the economic, social and scientific aspects. [14] |
| 6041 | International Association Of Volcanology And Chemistry Of The Earth'S Interior (Iav) | Promotes research in all matters relating to volcanic activity; coordinates research in mineralogy, chemistry and physical chemistry for the benefit of volcanologists. [14] |
| 6042 | Moon | The satellite of the earth. See librations of moon and phases of the moon. [14] |
| 6043 | Duct | A layer in the ocean or atmosphere where refraction and, probably, reflection result in the trapping and propagation within the layer of sound waves or electromagnetic waves. [14] |
| 6044 | Latitude | Angular distance from a primary great circle or plane. One of the coordinates used to describe a position, the other being longitude. [14] |
| 6045 | Projection | The representation of a figure on a surface, either plane or curved, according to a definite plan. In a perspective projection this is done by means of projecting lines emanating from a single point, which may be infinity. In cartography, any systematic arrangement of meridians and parallels portraying the curved surface of the sphere or spheroid upon a plane. Also called map projection or chart projection. In photography, the reduction or enlargement of a positive or negative, by projecting the image through a lens. [14] |
| 6046 | Format | The general plan or arrangement of a product. Specification of succession and type of repre-sentation of elements of information (numbers, text) on a medium. A fixed format is equivalent to a table, while free formats use delimiters to separate individual elements or "tags" (based on a directory) to identify elements. A set of formats or a complex format determines the structure of how information is represented on a medium. [14] |
| 6047 | Bel | A dimensionless unit for expressing the ratio of two values of power, the number of bels being the logarithm to the base 10 of the power ratio. In practice decibel is commonly used, the number of decibels being 10 times the logarithm to the base 10 of the power ratio. [14] |
| 6048 | Set | (v.i.). Of a celestial body, to cross the apparent horizon while descending. The opposite is rise. To establish, as to set a course. [14] |
| 6049 | Set | The direction toward which a current flows. [14] |
| 6050 | Rock | Any formation of natural origin that constitutes an integral part of the lithosphere. The natural occurring material that forms the firm, hard, and solid masses of the ocean floor. An isolated rocky formation or a single large stone, usually one constituting a danger to navigation. See rock awash, sunken rocks, pinnacle and rock which covers and uncovers. [14] |
| 6051 | Parallel | A circle (or approximation of a circle) on the surface of the earth, parallel to the equator and connecting points of equal latitude. Also called parallel of latitude. [14] |
| 6052 | Coast | (v.t.). To sail along or near a coast. [14] |
| 6053 | Ordinate | See coordinates: plane rectangular. [14] |
| 6054 | Bit | Short for "binary digit", the digit in binary number representation. A bit can only assume the binary values "0" and "1". A binary number representation is composed of bits just as a decimal number is represented by decimal digits. A unit of 8 bits is called a byte. It also stands for "basic indissoluble information unit", a unit used for measuring the information content in information theory. [14] |
| 6055 | Day | The duration of one rotation of the earth, or occasionally another celestial body, on its axis. It is measured by successive transits of a reference point on the celestial sphere over the meridian, and each type takes its name from the reference used. The period of daylight, as distinguished from night. [14] |
| 6056 | Way | The motion of a vessel through the water. [14] |
| 6057 | Coast | The edge or margin of the land next to the sea; the seashore. Sometimes defined as the meeting of the land and sea considered as the boundary of the land. [14] |
| 6058 | Ping | An acoustic pulse signal projected by an underwater transducer. [14] |
| 6059 | Character | As pertains to typography, a graphic symbol such as a letter of the alphabet, figure, punctuation mark or sign employed in recording language. In data processing, an element of a code set used for representing information. [14] |
| 6060 | Marine | An adjective meaning relating to navigation or shipping; relating to or connected with the sea; used, or adopted for use at sea. Sometimes called maritime, but maritime is more frequently applied to that which borders on the sea. [14] |
| 6061 | Cove | A small bay. [14] |
| 6062 | Pole | Either of the two points of intersection of the surface of a sphere or spheroid and its axis. The origin of a system of polar coordinates. Either of the two magnetic poles of a magnet. A long slender rod, as of timber or metal. Such a rod used for sounding is called sounding pole. [14] |
| 6063 | Pond | A small body of still water of artificial formation, its bed being either hollowed out of the soil or formed by embanking and damming up a natural hollow. [14] |
| 6064 | Bar | A ridge or succession of ridges of sand or other substances extending across the mouth of a river or harbor and which may obstruct navigation. Derived pressure in the cgs system. See also millibar. [14] |
| 6065 | Lens | A plane, convex, or concave combination of glass or transparent material surfaces adapted for changing the direction of light rays to enlarge or reduce the apparent size of objects. See achromatic lens, apochromatic lens, anallactic lens, objective lens, eyepiece, lens element, lens system, magnifying glass. [14] |
| 6066 | Type | In printing (typography) a metal block having a raised letter or figure which, when inked, is used to make an impression on paper or other material. Type can also be in the form of negative or positive stripping film. [14] |
| 6067 | Zone | An area in all parts of which the same time is kept. In general, each zone is 15° of longitude in width, with the Greenwich meridian (0° longitude) designated as the central meridian of zone 0 and the remaining zones centered on a meridian whose longitude is exactly divisible by 15°. Zones are used in connection with zone, standard, and daylight saving times. Also called time zone. [14] |
| 6068 | Bed | The ground upon which a body of water rests. [14] |
| 6069 | Ray | A beam of radiant energy of infinitesimal cross-section, such as a light ray. [14] |
| 6070 | Flow | The motion characteristic of a fluid. [14] |
| 6071 | Rise | A broad elevation that rises gently and generally smoothly from the sea floor. [14] |
| 6072 | Cloud | Visible aggregate of minute particles of liquid water or ice, or of both together, in suspension in the atmosphere. This aggregate may include larger particles of liquid water or ice, non-aqueous particles or solid particles, originating for example from industrial gases, smoke or dust. [14] |
| 6073 | Datum | Any numerical or geometrical quantity or set of such quantities which may serve as a reference or base for other quantities. In geodesy a datum is defined by a set of parameters specifying the reference surface or the reference coordinate system. Therefore two types of datums are required: a horizontal datum which forms the basis for computations of horizontal control surveys in which the curvature of the earth is considered, and a vertical datum to which elevations are referred. [14] |
| 6074 | Scope | The face of a cathode-ray tube of electronic equipment. The various methods of presenting the information on a radar scope are usually designated by letter, as a-scope, b-scope, etc. Also called indicator, scan, screen, although the alphabetical designations are not generally used with screen. [14] |
| 6075 | Origin | In surveying, the reference position from which angles or distances are reckoned. See also coordinates: origin of. [14] |
| 6076 | Atmosphere | Gaseous envelope which surrounds the earth. The gaseous envelope surrounding any star, planet, etc. A unit of pressure, equal to the pressure exerted per square centimeter by a column of mercury 760 mm high at a temperature of 0°c when the acceleration of gravity is 980.665 centimeters per second squared.. [14] |
| 6077 | Rise | A broad elevation that rises gently and generally smoothly from the sea floor. [14] |
| 6078 | Stand | See stand of tide. [14] |
| 6079 | Plat | (US Terminology). A diagram drawn to scale showing land boundaries and subdivisions, and identification of the several units shown thereon, and including one or more certificates indicating due approval. A plat differs from a map in that it does not necessarily show additional cultural, drainage and relief features. See also map: cadastral. [14] |
| 6080 | Photogram | A survey photograph. Either of a pair of stereoscopic photographs. [14] |
| 6081 | Layer | A single thickness, coat, fold or stratum. [14] |
| 6082 | Bearing | The horizontal direction of one terrestrial point from another, expressed as the angular distance from a reference direction. It is usually measured from 0° at the reference direction clockwise through 360°. The terms bearing and azimuth are sometimes used interchangeably, but in navigation the former customarily applies to terrestrial objects and the latter to the direction of a point on the celestial sphere from a point on the earth. A bearing is designated as true, magnetic, or compass as the reference direction is true, magnetic, or compass north. [14] |
| 6083 | Equator | The primary great circle of a sphere or spheroid such as the earth, perpendicular to the polar axis. [14] |
| 6084 | Cap | A feature with a rounded cap-like top. [14] |
| 6085 | Camera | A lightproof chamber or box in which the images of exterior objects are projected upon a sensitized plate or film, through an opening usually equipped with a lens or lenses, shutter and variable aperture. [14] |
| 6086 | Elevation | (1) the vertical distance of a point or a level, on the surface of the earth, measured from a specified vertical datum usually mean sea level. The term elevation is sometimes confused with altitude. For paper nautical charts, this term is often synonymous with height. (2) for navigational lights, such as lighthouses, the vertical distance of the focal point of the light measured from a specified vertical datum. (3) an area higher than its surroundings, as a hill. [14] |
| 6087 | Star | Celestial bodies which appear as points of light due to their great distance from the earth. They are self ‘luminous whereas planets shine only by reflection light. [14] |
| 6088 | Float | Any buoyant object attached to nets or fishing lines: term also used for the small buoys used for current observations. [14] |
| 6089 | Frequency | The number of vibrations or cycles in unit time. [14] |
| 6090 | Storm | Wind with a speed between 44 and 50 knots (beaufort scale wind force 10). Note: the term 'storm' has been substituted for the term 'whole gale' in US Weather bureau warnings. This term refers to wind speeds of 48-63 knots. [14] |
| 6091 | Stream | (v.t.). To place overboard and secure, as to stream a log, or stream a sea anchor. [14] |
| 6092 | Correction | A quantity which is applied to an observation or function thereof, to diminish or eliminate the effects of errors and obtain an improved value of the observation or function. It is also applied to reduce an observation to some arbitrary standard. The correction corresponding to a given error is of the same magnitude but of opposite sign. See chronometer correction, dip correction, index correction, instrumental correction, lead line correction, parallax correction, personal correction, polaris correction, refraction correction, semidiameter correction, sextant altitude correction, sky wave correction, orthometric correction, tidal difference. [14] |
| 6093 | Meteor | Phenomenon other than a cloud, observed in the atmosphere or on the surface of the earth, which consists of a precipitation, a suspension or a deposit of aqueous or non-aqueous liquid or solid particles, or a phenomenon of the nature of an optical or electrical manifestation. [14] |
| 6094 | Stream | Any river, brook, rivulet or course of running water. A steady current in the sea or in a river, especially the middle or most rapid part of a tide or current. A steady flow of a fluid, small solid particles, or radiant energy. [14] |
| 6095 | Head | A precipitous cape, or promontory. See also headland. That part of a rip current that has widened out seaward of the breakers. [14] |
| 6096 | Course | The intended horizontal direction of travel. It is measured from 0° at the reference direction clockwise through 360°; strictly for marine navigation, the term applies to the direction to be steered, which sometimes differs from the direction intended to be made good over the ground (see drift angle). The course is designated as true, magnetic, compass, or grid as the reference direction is true, magnetic, compass or grid north respectively. See course made good and track. The channel in which water flows. See also watercourse. [14] |
| 6097 | Section | Process of locating and coordinating a point from at least two existing control stations by observing horizontal directions from the control stations to the point. Also called intersection. [14] |
| 6098 | Altitude | The vertical distance of a level, a point or an object considered as a point (but not affixed to the surface of the earth), measured from a given datum, usually mean sea level. See also elevation and height.- 2. In astronomy, the vertical angle between the plane of the horizon and the line to a celestial body. See also angle of depression and angle of elevation. [14] |
| 6099 | Variation | The angle between the magnetic and geographical meridians at any place, expressed in degrees east or west to indicate the direction of magnetic north from true north. Also called magnetic variation, or magnetic declination. [14] |
| 6100 | Hydrograph | Used in oceanography. The tidal current vector hydrograph is the figure traced out by the tip of a vector representing the current over the tidal cycle. [14] |
| 6101 | Coordinates | Linear or angular quantities which designate the position of a point in relation to a given reference system. [14] |
| 6102 | Normal | In general, a straight line perpendicular to a surface or to another line. In geodesy, a straight line perpendicular to the surface of the spheroid. [14] |
| 6103 | Hour | A 24th part of a day. [14] |
| 6104 | Measurement | The (detailed) dimensions of a physical quantity. [14] |
| 6105 | Source | The point where a river rises. [14] |
| 6106 | Azimuth | A horizontal angle reckoned clockwise from the meridian. The horizontal direction of a celestial point from a terrestrial point, expressed as the angular distance from a reference direction. It is usually measured from 000° at the reference direction clockwise through 360°. An azimuth is often designated as true, magnetic, compass, grid, or relative as the reference direction is true, magnetic, compass, or grid north, or heading, respectively. Unless otherwise specified, the term is generally understood to apply to true azimuth which may be further defined as the arc of the horizon, or the angle at the zenith, between the north part of the celestial meridian or principal vertical circle and a vertical circle, measured from 000° at the north part of the principal vertical circle clockwise through 360°. When the angle is measured in either direction from north or south, and labelled accordingly, it is properly called azimuth angle; when measured either direction from east or west, and labeled accordingly, it is called amplitude. [14] |
| 6107 | Weather | Adj.). Of or pertaining to the direction from which the wind is blowing, as opposed to lee. [14] |
| 6108 | Weather | State of the atmosphere at a given time, as defined by the various meteorological elements. [14] |
| 6109 | Structure | The term "structure" shall include, without limitation, any pier, wharf, dolphin, weir, boom, breakwater, bulkhead, revetment, riprap, jetty, permanent mooring structure, power transmission line, permanently moored floating vessel, piling, aid to navigation, or any other obstacle or obstruction. [14] |
| 6110 | Rain | Precipitation of liquid water particles in the form of drops of more than 0.5 mm diameter or of smaller widely scattered drops. [14] |
| 6111 | Nautical | (Adj.). Of or pertaining to ships, navigation (chiefly marine) or seamen. In contrast, navigational refers to navigation only. [14] |
| 6112 | Deep | In oceanography, an obsolete term which was generally restricted to depths greater than 6,000 m. An unmarked fathom point on a lead line. [14] |
| 6113 | Radar | A method, system or technique of using beamed, reflected, and timed radio waves for detecting, locating, or tracking objects, and for measuring altitudes. The electronic equipment or apparatus used to generate, transmit, receive, and usually, to display radio scanning or locating waves; a radar set. The name 'radar' is derived from the words radio detecting and ranging. [14] |
| 6114 | Plot | (v.t.). To draw lines and points to represent certain conditions graphically, as the various lines and points on a chart or plotting sheet, representing the progress of a craft, a graphical solution of a problem, etc. [14] |
| 6115 | In photography, a copy made from a transparency by photographic means. [14] | |
| 6116 | Year | A period of one revolution of the earth around the sun. [14] |
| 6117 | Solid | Matter of stable shape, not liquid or fluid. [14] |
| 6118 | Triangulation | A method of surveying in which the stations are points on the ground at the vertices of a chain or network of triangles. The angles of the triangles are measured instrumentally and the sides are derived by computation from selected triangle sides called bases (or base lines), the lengths of which are obtained from direct measurements on the ground. [14] |
| 6119 | River | A relatively large natural stream of water. [14] |
| 6120 | Atmospheric | Electromagnetic wave resulting from an electric discharge (lightning) in the atmosphere. [14] |
| 6121 | Photogrammetry | The science or art of obtaining reliable measurements from photographs. [14] |
| 6122 | Cycle | One complete series of events or phenomena that recur regularly in the same sequence. See also frequency, hertz, period. [14] |
| 6123 | Theodolite | A precision surveying instrument consisting of an alidade with a telescope. It is mounted on an accurately graduated circle and is equipped with necessary levels and reading devices. Sometimes, the alidade carries a graduated vertical circle. [14] |
| 6124 | Plotting | See plot. [14] |
| 6125 | Micrometer | An auxiliary device to provide measurement of very small angles or dimensions, by an instrument such as a telescope. See micrometer: filar, micrometer: transit. [14] |
| 6126 | Environment | The sum total of all external conditions which may affect an organism, community, material, or energy if brought under the influence of these external conditions. [14] |
| 6127 | Wave Length | The distance between corresponding points of two successive periodic waves in the direction of propagation, for which the oscillation has the same phase. Unit of measurement in meters. Also written as one word. [14] |
| 6128 | Revolution | Motion of a celestial body in its orbit; circular motion about an axis usually external to the body. The terms revolution and rotation are often used interchangeably but, with reference to the motions of a celestial body, revolution refers to the motion in an orbit or about an axis external to the body, while rotation refers to motion about an axis within the body. Thus, the earth revolves about the sun annually and rotates about its axis daily. [14] |
| 6129 | Echo Sounder | An instrument for determining the depth of water by measuring the time interval between the emission of a sonic or ultrasonic signal and the return of its echo from the bottom. Also called echo sounding instrument (or apparatus), sonic depth finder, or ultrasonic depth finder, as appropriate. See also sub-bottom profiler, swath(e) sounding system. [14] |
| 6130 | Radiobeacon | A radio transmitter which emits a distinctive or characteristic signal used for the determination of bearings, courses or location. One intended to mark a specific location is called marker beacon. [14] |
| 6131 | Transmitter | One who or that which transmits or sends anything, particularly a radio transmitter. [14] |
| 6132 | Wave Height | The vertical distance between a wave crest and the preceding wave trough. [14] |
| 6133 | Acceleration | The rate of change of velocity. [14] |
| 6134 | Tropic Tide | See tide. [14] |
| 6135 | Diurnal Tide | See tide. [14] |
| 6136 | Flood Stream | The horizontal movement of water associated with the rising tide. Flood streams generally set toward the shore, or in the direction of the tide progression. Also called flood, flood current or ingoing stream. [14] |
| 6137 | Reproduction | In cartography, the processes involved in printing copies from an original drawing. The principal processes are photography, lithography (or engraving), and printing. A printed copy of an original drawing, made by any of the processes of reproduction. [14] |
| 6138 | Sound Signal | Any sound produced to convey intelligence, as a fog signal. [14] |
| 6139 | Small Scale | See scale. [14] |
| 6140 | Axis Of Lens | The straight line which passes through the centers of curvature of the lens surfaces. Also called principal axis, optical axis or lens axis. [14] |
| 6141 | Gravity Wave | See wave. [14] |
| 6142 | Smooth Sheet | (US Terminology). See fair chart. [14] |
| 6143 | Spring Tides | Tides of increased range or tidal currents of increased speed occurring semimonthly as the result of the Moon being new or full. The spring range (Sg) of tide is the average range occurring at the time of spring tides and is most conveniently computed from the harmonic constants. It is larger than the mean range where the type of tide is either semi diurnal or mixed, and is of no practical significance where the type of tide is predominantly diurnal. The average height of the high waters of the spring tides is called spring high water or mean high water springs (MHWS) and the average height of the corresponding low waters is called spring low water or mean low water springs (MLWS). [22] |
| 6144 | Water Depth | Vertical distance between the sea floor and still water level. NOTE 1 As there are several options for the still water level (see Still Water Level), there can be several water depth values. Generally, design water depth is determined to LAT or to mean sea level. NOTE 2 The water depth used for calculating wave kinematics varies between the maximum water depth of the highest astronomical (HAT) tide plus a positive storm surge, and the minimum water depth of the lowest astronomical (LAT) tide less a negative storm surge, where applicable. The same maximum and minimum water depths are applicable to bottom founded and floating structures, although water depth is usually a much less important parameter for floating structures. Water depth is, however, important for the design and analysis of the mooring system and risers for floating structures. [15] |
| 6145 | Compass Card | That part of a compass on which the direction graduations are placed. Also referred to as card. [14] |
| 6146 | Datum: Chart | A permanently established surface from which soundings or tide heights are referenced, usually low water. Also called datum, datum level, datum plane, hydrographic datum, reference level, reference plane. See datum: tidal. [14] |
| 6147 | Magnetic Dip | See dip. [14] |
| 6148 | Surface Mark | A station mark used in addition to the underground mark, over which it is plumbed. [14] |
| 6149 | Tidal Stream | See current: tidal. [14] |
| 6150 | Upper Branch | That half of a meridian or celestial meridian from pole to pole which passes through a place or its zenith. [14] |
| 6151 | Wave Period | The time, in seconds, required for a wave crest to traverse a distance equal to one wavelength. [14] |
| 6152 | Bar Sweeping | A sweeping procedure using a beam suspended horizontally under a vessel. The sweep passing over the bottom may be equipped with rockers or other sensors to record contact with the bottom. [14] |
| 6153 | Bermuda High | A semipermanent high in the subtropical high-pressure belt centered near 30° latitude. The bermuda high is located over the Atlantic Ocean off the east coast of North America. The pacific high is located off the west coast of North America. See subtropical high. [1] |
| 6154 | Carrier Wave | See wave. [14] |
| 6155 | Circle Sheet | (US Terminology). A boat sheet or a smooth sheet on which intersecting systems of curves are drawn, each curve corresponding to the locus of some angle between two stations. Positions are plotted on circle sheets at the intersection of the loci of two observed angles, each locus being found by interpolation between the curves drawn on the sheet. Circle sheets are prepared and employed in hydrographic surveys for plotting fixes without the use of protractor. Also called standard circle sheet; formerly called sextant chart. See also fixed angle plot, and lattice. [14] |
| 6156 | Delimitation | The process of establishing the line(s) of delimitation in the context of the united nations' law of the sea convention. [14] |
| 6157 | Eccentricity | The amount of deviation from a center. [14] |
| 6158 | Geomagnetism | The magnetism of the earth. Also called terrestrial magnetism. [14] |
| 6159 | Ground Speed | In air navigation, the rate of motion of an aircraft along its track with relation to the ground. See also air speed. [14] |
| 6160 | Leading Line | (British terminology). A line passing through two or more clearly defined charted objects, and along which a vessel can approach safely. [14] |
| 6161 | Lens Element | One lens of a complex lens system. [14] |
| 6162 | Orthomorphic | (Adj.). Preserving the correct shape; of a projection which gives no local distortion. See projection: conformal. [14] |
| 6163 | Parallax: Y- | In photogrammetry, the difference between the perpendicular distances of the two images of a point on a pair of photographs from the vertical plane containing the air base. The existence of y-parallax is an indication of tilt in either or both photographs and/or a difference in flight heights, and interferes with stereoscopic examination of the pair. Also called vertical parallax or want of correspondence. [14] |
| 6164 | Small Circle | See circle. [14] |
| 6165 | Spring Range | The mean semidiurnal range of tide when spring tides are occurring. The mean difference in height between mean high water springs and mean low water springs. Also called mean spring range. [14] |
| 6166 | Traffic Lane | An area within defined limits in which one-way traffic is established. Natural obstacles, including those forming separation zones, may constitute a boundary. [14] |
| 6167 | Time Signal | See signal. [14] |
| 6168 | Arid Climate | An extremely dry climate, drier than the semi-arid climate. Often referred to as a true desert climate. [1] |
| 6169 | Atomic Clock | See clock. [14] |
| 6170 | Cloud Amount | The fraction of the sky covered by the clouds of a certain genus, certain species, certain variety, certain layer, or of a certain combination of clouds. Also called partial cloud amount. See cloud genera. [14] |
| 6171 | Compass Rose | A circle graduated in degrees clockwise from 0° (north) to 360° printed on a chart for use as a protractor. Compass roses are also placed at other convenient locations to facilitate measurements of directions. They may be oriented to the true or the magnetic north. [14] |
| 6172 | Conformality | The special property of conformal projection, i.e. That of having correct relationship about a point. [14] |
| 6173 | Cotidal Line | A line on a chart passing through all points where high water occurs at the same time. [14] |
| 6174 | Cumulonimbus | An exceptionally dense and vertically developed cloud, often with a top in the shape of an anvil. The cloud is frequently accompanied by heavy showers, lightning, thunder, and sometimes hail. It is also known as a thunderstorm cloud. [1] |
| 6175 | Depth Finder | An instrument for the measurement of the depth of water, particularly an echo sounder. [14] |
| 6176 | Ebb Interval | Short for strength of ebb interval. The interval between the transit of the moon over the meridian of a place and the time of the following strength of ebb. [14] |
| 6177 | Ekman Spiral | Spiral, polar diagram of the extremities of the wind vectors at different heights, representing the variation of the wind with height in the friction layer on the basis of various simplifying assumptions. The ekman spiral is also applied to the variation of wind-driven ocean currents with depth below the surface. [14] |
| 6178 | Fishing Zone | The offshore zone in which exclusive fishing rights and management are held by the coastal nation. [14] |
| 6179 | Fluorescence | Emission of light or other radiant energy as a result of and only during absorption of radiation from some other source. See luminescence and phosphorescence. [14] |
| 6180 | Fujita Scale | A scale developed by t. Theodore Fujita for classifying tornadoes according to the damage they cause and their rotational wind speed. (see also enhanced Fujita scale.) [1] |
| 6181 | Ground Nadir | See nadir. [14] |
| 6182 | Gyro Compass | See compass: gyroscopic. [14] |
| 6183 | Hydrocarbons | Chemical compounds composed of only hydrogen and carbon. They are included under the general term volatile organic compounds (VOCs). [1] |
| 6184 | Interrogator | A radar transmitter which sends out a pulse that triggers a transponder. An interrogator is usually combined in a single unit with a responsor, which receives the reply from a transponder and produ-ces an output suitable for feeding to a display system, the combined unit being called an interrogator-responsor. Short for interrogator-responsor. Also called challenger. [14] |
| 6185 | Laminar Flow | Low in which the fluid moves smoothly along streamlines which are arranged in parallel layers or sheets; opposite of turbulent flow. Also called streamline flow. [14] |
| 6186 | Last Quarter | See phases of the moon. [14] |
| 6187 | Marine Chart | See chart: nautical. [14] |
| 6188 | Mooring Buoy | See buoy. [14] |
| 6189 | Optical Axis | See axis of lens. [14] |
| 6190 | Pacific High | A semipermanent high in the subtropical high-pressure belt centered near 30° latitude. The bermuda high is located over the atlantic ocean off the east coast of north america. The pacific high is located off the west coast of north america. Also see subtropical high. [1] |
| 6191 | Perturbation | Disturbance in the orbital path of a celestial body, natural or artificial, due to attraction of another body. See lunar inequality. [14] |
| 6192 | Psychrometer | Instrument used to measure the humidity of the atmosphere. It comprises two identical thermo-meters, the bulb of one of which is dry, while that of the other is wet and covered by a film of pure water or ice. [14] |
| 6193 | Radar Target | An object which reflects a sufficient amount of a radar signal to produce an echo signal on the radar screen. [14] |
| 6194 | Random Error | see error: accidental. [14] |
| 6195 | Relief Model | A scaled representation in three dimensions of a section of the crust of the earth, or of another heavenly body. A relief model primarily designed to display features on the surface of the earth is sometimes known as a topographic model. [14] |
| 6196 | Semidiameter | Half the angle at the observer subtended by the visible disk of a celestial body. Sextant altitudes of the sun and moon should be corrected for semidiameter unless the center is observed, as with a bubble sextant. [14] |
| 6197 | Spoil Ground | a sea area where dredged material is deposited. See also dumping ground. [14] |
| 6198 | Subpolar Low | A belt of low pressure located between 50° and 70° latitude. In the northern hemisphere, this belt consists of the Aleutian low in the North Pacific and the Icelandic low in the North Atlantic. In the southern hemisphere, it exists around the periphery of the Antarctic continent. [1] |
| 6199 | Surface Wave | See wave. [14] |
| 6200 | Tide Station | See station. [14] |
| 6201 | Tide: Double | A double-headed tide. Also called agger. See high water: double and low water: double. [14] |
| 6202 | Transparency | In oceanography, the property of water to transmit light of different wavelengths. Transparency sometimes is measured in percent of radiation that penetrates a distance of one metre. Sometimes it is expressed as the average depth at which a secchi disc disappears and reappears. In photography, a photographic print on a clear base, especially adaptable for viewing by transmitted light. Also, the light-transmitting capability of a material. [14] |
| 6203 | Tropic Range | Short for great tropic range. [14] |
| 6204 | Year: Civil | A year of the gregorian calendar of 365 days in common years, or 366 days in leap (or bissextile) years. [14] |
| 6205 | Aclinic Line | See equator: magnetic. [14] |
| 6206 | Aleutian Low | The subpolar low-pressure area that is centered near the Aleutian Islands on charts that show mean sea- level pressure. [1] |
| 6207 | Alphanumeric | Contraction of alphabetic-numeric. Characters including letters of the alphabet and numbers. [14] |
| 6208 | Angle Of Cut | See angle: crossing. [14] |
| 6209 | Angular Rate | See speed: angular. [14] |
| 6210 | Antimeridian | The meridian which is 180 deg of longitude from a given meridian. One meridian with its anti-meridian constitutes a complete great circle. [14] |
| 6211 | Barrier Reef | A coral reef fronting the shore, at some distance from it, and separated from it by a lagoon or a navigable channel of moderate depth. See also fringing reef. [14] |
| 6212 | Bourdon Tube | Closed, curved, flexible tube of elliptic cross-section, which is deformed, according to type, by variations of atmospheric pressure or temperature and so provides a measurement of the particular element. [14] |
| 6213 | Cartographer | Person employed in drawing and constructing charts or maps. [14] |
| 6214 | Cirrocumulus | A high cloud that appears as a white patch of clouds without shadows. It consists of very small elements in the form of grains or ripples. [1] |
| 6215 | Cirrostratus | High, thin, sheetlike clouds, composed of ice crystals. They frequently cover the entire sky and often produce a halo. [1] |
| 6216 | Cloud Genera | Ain characteristic mutually exclusive forms of clouds, constituting the basis of the cloud classification included in the international cloud atlas, 1956. The cloud genera are ten in number: cirrus, cirrocumulus, cirrostratus, altocumulus, altostratus, nimbostratus, stratocumulus, stratus, cumulus, cumulonimbus. [14] |
| 6217 | Compass Bowl | That part of a compass in which the compass card is mounted. A magnetic compass bowl is usually filled with liquid. The compass bowl turns with the craft while the compass card remains essentially in a north-south direction. [14] |
| 6218 | Condensation | The process by which water vapor becomes a liquid. [1] |
| 6219 | Conductivity | The ability to transmit, as electricity, heat, sound etc. [14] |
| 6220 | Current Line | See current pole. [14] |
| 6221 | Current Pole | A pole used to determine the direction and speed of a surface current. The direction is determined by the direction of motion of the pole, and the speed by the amount of an attached graduated line (called current line or log line) paid out in a specified time. [14] |
| 6222 | Danger Angle | The maximum (or minimum) angle between two points, as observed from a craft, indicating the limit of safe approach to an offlaying danger. [14] |
| 6223 | Echo Ranging | The determination of distance by measuring the time interval between transmission of a radiant energy signal, usually sound, and the return of its echo. [14] |
| 6224 | Ekman Bottle | A reversing water bottle which can be closed watertight by means of plates seated in rubber. When at the desired depth, the reversing mechanism is tripped by a messenger. [14] |
| 6225 | Enclosed Sea | A gulf, basin, or sea surrounded by two or more states and connected to another sea or the ocean. [14] |
| 6226 | Falling Tide | See tide. [14] |
| 6227 | False Bottom | See phantom bottom. [14] |
| 6228 | False Origin | See coordinates: false. [14] |
| 6229 | False Target | See echo: false. [14] |
| 6230 | Faye Anomaly | See free-air anomaly. [14] |
| 6231 | Fishing Area | See fishing ground. [14] |
| 6232 | Flinders Bar | A bar of soft unmagnetized iron placed vertically near a magnetic compass to counteract deviation caused by magnetic induction in vertical soft iron of the craft. [14] |
| 6233 | Floating Ice | Any form of ice found floating in water. [14] |
| 6234 | Ground Layer | Thin layer of air adjacent to the earth's surface and of a depth which has been variously given as 10 m to 100 m. Also called surface boundary layer. [14] |
| 6235 | Ground Range | See ground distance. [14] |
| 6236 | Heat Equator | See equator: thermal. [14] |
| 6237 | Historic Bay | Historic bays are those over which the coastal state has publicly claimed and exercised jurisdiction and this jurisdiction has been accepted by other states. Historic bays need not match the definition of "bay" contained in the united nations convention on the law of the sea. [14] |
| 6238 | Horizon Line | See horizon trace. [14] |
| 6239 | Ice Piedmont | Ice covering a coastal strip of low-lying land backed by mountains. The surface of an ice piedmont slopes gently seawards and may be anything from 50 m to 50 km wide, fringing long stretches of coastline with ice cliffs. Ice piedmonts frequently merge into ice shelves. [14] |
| 6240 | Igneous Rock | Rock formed by solidification of molten material or magma. [14] |
| 6241 | Inclinometer | An instrument for measuring the inclination to the horizontal of the longitudinal axis of an aircraft. See dip circle, wire angle indicator. [14] |
| 6242 | Inogen Light | Leading mark based on the interference effect of 3 separately placed raster boards. An arrow pointing in the direction of the line is displayed when not sailing along the leading line. [14] |
| 6243 | Interference | Extraneous signals, noises, etc., that hinder proper reception of the desired signal in electronic equipment. See wave interference. [14] |
| 6244 | Landing Area | In aeronautical terminology, the part of the movement area intended for the landing or take-off run of aircraft. [14] |
| 6245 | Lateral Buoy | See lateral mark [14] |
| 6246 | Lateral Mark | In the iala maritime buoyage system a navigation mark used to indicate the port or starboard side of the route to be followed. They are generally used for well-defined channels and are used in conjunction with a conventional direction of buoyage. See also lateral system. [14] |
| 6247 | Lee-Side Low | Storm systems (extratropical cyclones) that form on the downwind (lee) side of a mountain chain. In the united states lee-side lows frequently form on the eastern side of the rockies and sierra nevada mountains. [1] |
| 6248 | Light Sector | A sector in which a navigational light is visible. See arc of visibility. [14] |
| 6249 | Light Vessel | See lightship. [14] |
| 6250 | Lower Branch | That half of a meridian or celestial meridian from pole to pole which passes through the antipode or nadir of a place. [14] |
| 6251 | Luminescence | Any emission of light at temperatures below that required for incandescence. See bioluminescence, fluorescence, phosphorescence. [14] |
| 6252 | Map Parallel | See axis of homology. [14] |
| 6253 | Normal Water | A standard sea water preparation, the chlorinity of which lies between 19.30 and 19.50 per mille (0/00) and has been determined to within ± 0.001 per mille. Normal water is used as a convenient comparison standard for chlorinity measurements of sea water samples by titration. It is prepared by the hydrographical laboratories, copenhagen, denmark. Also called standard sea water. [14] |
| 6254 | Object-Glass | See objective lens. [14] |
| 6255 | Oscillograph | A device for recording or indicating oscillations or changes in an electric current. [14] |
| 6256 | Paranthelion | Photometeor of the halo family, consisting of white, round, luminous spots, having a diameter slightly greater than that of the sun, which appears at 120° from it in the case of ordinary paranthe-lia, and at 90° in the case of extraordinary paranthelia. The height of the spots above the horizon is that of the sun. [14] |
| 6257 | Partial Tide | See tide. [14] |
| 6258 | Pilot Waters | Areas in which the services of a marine pilot are available. Waters in which navigation is by piloting. More usually called pilotage waters in British terminology. [14] |
| 6259 | Polar Aurora | See aurora. [14] |
| 6260 | Polar Circle | Either the arctic circle (north polar circle) or the antarctic circle (south polar circle). [14] |
| 6261 | Polarization | A condition of radiant energy in which the vibrations take place in a regular manner, as in a straight line, circle or ellipse, in a plane perpendicular to the path of travel. [14] |
| 6262 | Primary Tide | See tide. [14] |
| 6263 | Quartz Clock | See clock: crystal. [14] |
| 6264 | Radar Beacon | A transponder beacon transmitting a coded signal on radar frequency, permitting an interrogating craft to determine the bearing and range of the transponder. Also called racon. See ramark. [14] |
| 6265 | Radiant Flux | See flux. [14] |
| 6266 | Range Finder | An optical instrument for measuring the distance to an object. [14] |
| 6267 | Rate Station | See drift station. [14] |
| 6268 | Registration | Correct positioning of one component of a composite map image in relation to the other compo-nents. Achieved, for example, by punching sets of holes, having a fixed horizontal relationship to each other, in each component sheet and then attaching the components together using specially designed fasteners. See also punch register system. [14] |
| 6269 | Sidereal Day | See day. [14] |
| 6270 | Solar System | The sun and other celestial bodies within its gravitational influence, including planets, planetoids, satellites, comets, and meteors. [14] |
| 6271 | Sounding Rod | See sounding pole. [14] |
| 6272 | Special Mark | In the IALA maritime buoyage system, a special mark indicates an area or feature referred to in nautical documents; it is not primarily intended to assist navigation. [14] |
| 6273 | Stadia Lines | Two or more horizontal wires fixed in the diaphragm at equal distances from the axis of telescopes, of theodolites and levels. Also called stadia wires. [14] |
| 6274 | Stratosphere | Region of the atmosphere, situated between the tropopause and the stratopause, in which the temperature generally increases with height. From an imperfect analogy with the atmosphere, the term is sometimes applied in oceanography to the nearly uniform masses of cold, deep and bottom water of middle and low latitudes. This layer is separated from the troposphere by the thermocline. [14] |
| 6275 | Subtense Bar | A horizontally held bar of precisely determined length, used to measure distances by observing the angle it subtends at the distance to be measured. [14] |
| 6276 | Tabular Berg | A flat-topped iceberg. Most tabular bergs form by breaking from an ice shelf and show horizontal banding. [14] |
| 6277 | Tide Reducer | The correction that must be applied to a recorded sounding for the height of tide above or below the datum of reference at the time of sounding. [14] |
| 6278 | Transit Axis | See axis: horizontal. [14] |
| 6279 | Traverse Net | See triangulation net. [14] |
| 6280 | True Azimuth | See azimuth. [14] |
| 6281 | Type Of Tide | The characteristic feature of the tide (tidal current) determined from the combination of its diurnal and semidiurnal components. Tides are classified as semidiurnal, mixed and diurnal, but there are no sharply defined limits separating the groups. [14] |
| 6282 | Water Colour | See sea water: colour of. [14] |
| 6283 | Wet Density | The ratio of the weight of the solid particles of a bottom sediment and the contained moisture to its total volume. [14] |
| 6284 | Almanac: Air | A periodical publication containing various computed astronomical data primarily intended for use in air navigation. See also ephemeris. [14] |
| 6285 | Anastigmatic | (Adj.). Free from astigmatism. Corrected for astigmatism. [14] |
| 6286 | Anchor Berth | A designated area of water where a vessel, seaplane, etc. May anchor. [14] |
| 6287 | Angle: Check | See check angle. [14] |
| 6288 | Angle: Drift | See drift angle. [14] |
| 6289 | Angle: Phase | See phase angle. [14] |
| 6290 | Angle: Slope | See slope angle. [14] |
| 6291 | Apparent Sun | See sun. [14] |
| 6292 | Argillaceous | (Adj.). Applied to all rocks or sediments composed partly or completely of clay. [14] |
| 6293 | Astenosphere | See mantle. [14] |
| 6294 | Astronautics | The science of locomotion and travel outside the earth's atmosphere, involving the problems of artificial satellites and of interplanetary journeys. [14] |
| 6295 | Autopositive | A material which gives a positive copy from a positive transparency (or a negative from a negative) by direct processing. [14] |
| 6296 | Axis Of Tilt | In photogrammetry, a line through the perspective center perpendicular to the principal plane. [14] |
| 6297 | Azimuth Mark | A mark set at a significant distance from a triangulation or traverse station to mark the end of a line for which the azimuth has been determined, and to serve as a starting or reference azimuth for later use. [14] |
| 6298 | Back Azimuth | See azimuth. [14] |
| 6299 | Backing Wind | Counter-clockwise change of wind direction, in either hemisphere. [14] |
| 6300 | Basic Survey | A hydrographic survey so complete and thorough that it does not need to be supplemented by other surveys, and is adequate to supersede, for charting purposes, all prior hydrographic surveys of the area. [14] |
| 6301 | Basin: Tidal | A basin affected by tidal forces in which water can be kept at a desired level by means of a gate. [14] |
| 6302 | Beach Comber | See comber. [14] |
| 6303 | Beam Compass | An instrument consisting of a beam or rod with sliding sockets that hold pencil, pen, or steel points, used together with a scale for plotting exact lengths or for drawing large circles. [14] |
| 6304 | Binocular(S) | An optical instrument consisting of a pair of telescopes joined so as to be adaptable to the use of both eyes simultaneously. [14] |
| 6305 | Boat Compass | See compass. [14] |
| 6306 | Border Break | A cartographic technique to extend cartographic detail of a map or chart beyond the neatline into the margin to show important features. This technique eliminates the necessity of producing an additional chart. Also called blister. [14] |
| 6307 | Border Scale | See scale. [14] |
| 6308 | Boulder Clay | See till. [14] |
| 6309 | Bridge: Draw | A general name for bridges of which part or the entire span of the bridge may be raised or drawn aside to allow ships to pass through. [14] |
| 6310 | Bridge: Lift | A movable bridge which is capable of being lifted vertically to allow vessels to pass beneath. [14] |
| 6311 | Broadside On | Beam on, as to the wind or sea. [14] |
| 6312 | Broken Water | An area of small waves and eddies occurring in what otherwise is a calm sea. [14] |
| 6313 | Buoy: Survey | A buoy used by survey ships to control hydrographic surveys. See also buoy-control method. [14] |
| 6314 | Cable Length | See cable. [14] |
| 6315 | Caution Area | An area to which a cautionary note applies where the mariner needs to be aware of special circumstances influencing the safety of navigation. [14] |
| 6316 | Centrosphere | The central core of the earth, composed of dense material, and making up most of its mass. Also called barysphere or core. [14] |
| 6317 | Cesium Clock | See clock: cesium. [14] |
| 6318 | Channel: Sea | A long, narrow, u-shaped or v-shaped shallow depression of the sea floor usually occurring on a gently sloping plain or fan. A continuously sloping, elongated depression commonly found in cones or abyssal plains and customarily bordered by levees on one or both sides. [14] |
| 6319 | Chart Symbol | A character, letter, or similar graphic representation used on a chart to indicate some object, characteristic, etc. May be called map symbol when applied to any map. [14] |
| 6320 | Chart: Blank | A chart with a reduced amount of detail serving as cartographic basis for graphical documents of all kinds and for the depiction of reference data. [14] |
| 6321 | Chart: Datum | A chart depicting the undulations of the geoid. [14] |
| 6322 | Chart: Field | A nautical chart prepared at the survey site, usually contains limited, and/or unedited information. [14] |
| 6323 | Chart: Index | An outline chart showing the limits and identifying designation of navigational charts, volumes of sailing directions, or list of lights. [14] |
| 6324 | Chart: Pilot | A chart containing information required for safe navigation, including ocean currents, ice at sea, wind roses, storm tracks, isotherms, magnetic variation, great circle routes, limits of trade winds, etc. [14] |
| 6325 | Chart: Polar | A chart of the polar areas, or one on a polar projection. [14] |
| 6326 | Chart: Radar | A chart designed primarily for use with radar, or one suitable for this purpose. [14] |
| 6327 | Chinook Wind | A warm, dry wind on the eastern side of the rocky mountains. In the alps, the wind is called a foehn. [1] |
| 6328 | Chromosphere | The reddish layer of incandescent gases around the sun, visible at a total eclipse. A similar layer surrounding a star. [14] |
| 6329 | Circular Fix | See fix. [14] |
| 6330 | Closing Line | A line that divides the internal waters and territorial seas of a coastal state or the archipelagic waters of an archipelagic state. [14] |
| 6331 | Coding Delay | An arbitrary time delay in the transmission of pulse signals. In the loran system this is inserted between the transmission of master and slave signals to prevent zero or small readings, and aid in distinguishing between master and slave station signals. [14] |
| 6332 | Coelenterate | One of a phylum of two-staged (sessile and free-floating) organisms. The sessile stage basically is cylindrical and is called a polyp; the free-swimming stage is disc or bell shaped and is called a medusa or jellyfish. [14] |
| 6333 | Colour Plate | A general term for a press plate from which any given colour is printed. [14] |
| 6334 | Colour Proof | The final proof for checking before printing utilizing all of the negatives involved to produce a copy of the final product with all of the required colors. See also proof. [14] |
| 6335 | Compass: Box | See declinatoire. [14] |
| 6336 | Compass: Sky | A type of astro compass which utilizes the polarization of sunlight in the sky, designed for use in the arctic during long periods of twilight. It operates whenever the zenith is clear whether or not the sun is visible, but when the sun is more than about 6.5° below or 10° above the horizon, readings are uncertain. [14] |
| 6337 | Compass: Sun | A form of astro compass utilizing the shadow of a gnomon. [14] |
| 6338 | Compass: Wet | See compass: liquid. [14] |
| 6339 | Conical Buoy | A buoy the above water part of which is in the shape of a cone. [14] |
| 6340 | Control Mark | A specific object on the ground whose position and/or elevation has been determined or is to be determined. [14] |
| 6341 | Copper Plate | Polished plate on which manuscript drawings were formerly engraved for the printing of charts. [14] |
| 6342 | Core Catcher | A mechanical device located at the bottom of a core barrel to retain a bottom sample. [14] |
| 6343 | Course: Grid | See course. [14] |
| 6344 | Course: True | See course. [14] |
| 6345 | Current: Ebb | See ebb stream. [14] |
| 6346 | Current: Rip | The return flow of water piled up on shore by incoming waves and wind. [14] |
| 6347 | Curve: Depth | See depth curve. [14] |
| 6348 | Cyclogenesis | The development or strengthening of middle-latitude (extratropical) cyclones. [1] |
| 6349 | Datum: Tidal | A level of the sea defined by some phase of the tide, from which water depths and heights of tide are reckoned. [14] |
| 6350 | Deceleration | Negative acceleration. [14] |
| 6351 | Declinatoire | A combined magnetic compass and straight edge, suitable for use on a plane table to mark the magnetic meridian. Also known as a box compass or trough compass. See also compass: tubular. [14] |
| 6352 | Declinometer | A magnetic instrument similar to a surveyor's compass, but arranged so that the line of sight can be rotated to conform with the needle or to any desired setting on the horizontal circle. Used in determining the magnetic declination. See variation. [14] |
| 6353 | Densitometer | An electric instrument designed to accurately measure optical density or tone values and used in place of the human eye for such purposes. [14] |
| 6354 | Distributary | A river branch which flows away from the main stream without returning to it, as in a delta. [14] |
| 6355 | Dredged Area | An area of the bottom of a body of water which has been deepened by dredging. [14] |
| 6356 | Drift Bottle | An identifiable sealed bottle which is released into the sea for use in studying currents. [14] |
| 6357 | Drum Plotter | A plotter which uses a rotating drum or cylinder to move the drawing base in the direction of one coordinate axis while the plotting head only moves along the other coordinate axis. [14] |
| 6358 | Dumb Compass | See pelorus. [14] |
| 6359 | Ebb Strength | Phase of the ebb tidal current at the time of maximum velocity. Also, the velocity at this time. Also called strength of ebb. [14] |
| 6360 | Electric Log | See log. [14] |
| 6361 | Epipolar Ray | The line on the plane of a photograph joining the epipole and the image of an object. Also expressed as the trace of an epipolar plane on a photograph. [14] |
| 6362 | Error: Gross | The result of carelessness or a mistake; may be detected through repetition of the measurement. Also called blunder. [14] |
| 6363 | Error: Index | The instrumental error which is constant and attributable to displacement of a vernier or some analogous effect. [14] |
| 6364 | Error: Swirl | The additional error in the reading of a magnetic compass during a turn, due to friction in the compass liquid. [14] |
| 6365 | Evaporimeter | Instrument for measuring the amount of water evaporated into the atmosphere during a given time interval. Also called atmometer, atmidometer. [14] |
| 6366 | Fair Tracing | (British terminology). A paper tracing of moderate size for transferring the work from the field boards to the fair charts. [14] |
| 6367 | Fairway Buoy | A buoy marking a fairway, with safe water on both sides. [14] |
| 6368 | Fall Streaks | Falling ice crystals that evaporate before reaching the ground. [1] |
| 6369 | Fata Morgana | The name originally given to a multiple mirage phenomenon often observed over the straits of messina, and supposed to be the work of the faity (in italian: fata) morgana; later, it was applied to any impressive multiple mirage. [14] |
| 6370 | Fathom Curve | See fathom line, depth curve. [14] |
| 6371 | Feature Code | An alphanumeric code (label) attached to all point, line or area data describing a cartographic feature of particular quality. [14] |
| 6372 | Fishing Reef | See fish haven. [14] |
| 6373 | Fix: Running | A position determined by crossing lines of position obtained at different times and advanced or retired to a common time, the expression being applied to a position determined by advancing and retiring a line over a considerable period of time. [14] |
| 6374 | Flight Strip | A succession of overlapping aerial photographs taken along a single course. [14] |
| 6375 | Frontal Wave | A wavelike deformation along a front in the lower levels of the atmosphere. Those that develop into storms are termed unstable waves, while those that do not are called stable waves. [1] |
| 6376 | Function Key | A special key on a computer which performs a preprogrammed function. [14] |
| 6377 | Funnel Cloud | A funnel-shaped cloud of condensed water, usually extending from the base of a cumuliform cloud. The rapidly rotating air of the funnel is not in contact with the ground; hence, it is not a tornado. [1] |
| 6378 | Gale Warning | See warning. [14] |
| 6379 | Galvanometer | An instrument for detecting and determining the intensity and direction of an electric current. [14] |
| 6380 | Gauge: Depth | A general term for an instrument made to indicate depth of water, especially one in which sea depths are indicated by pressure of water against a spring, or by degree of compression of air in a tube. [14] |
| 6381 | Gauge: Float | A tide gauge that is operated by a float in a long, vertical stationary box to which the tide is admitted through an opening in the bottom. Also called box gauge. [14] |
| 6382 | Graving Dock | See dock: dry. [14] |
| 6383 | Grid Azimuth | See azimuth. [14] |
| 6384 | Grid Bearing | See bearing. [14] |
| 6385 | Ground Plane | In photogrammetry, the horizontal plane passing through the ground nadir of a camera station. [14] |
| 6386 | Ground Swell | A long high ocean swell; also, this swell as it rises to prominent height in shallow water, however, usually not so high or dangerous as blind rollers. [14] |
| 6387 | Ground Truth | The information acquired by a field study to calibrate or verify geographical data acquired by remote sensing. [14] |
| 6388 | Gyro Sextant | See sextant. [14] |
| 6389 | Harbour Line | The line beyond which wharves and other structures cannot be extended. [14] |
| 6390 | Headwater(S) | The streams from the sources and upper parts of a river. [14] |
| 6391 | Hill Shading | A method of indicating relief on maps by shading normally the slopes facing south and east, i.e. It is assumed that the area mapped is illuminated from the north-west. The method is often used in association with contours. [14] |
| 6392 | Hydrographer | A person who studies and practices the science of hydrography; the term is often applied to the person in charge of a hydrographic department or office of a country. [14] |
| 6393 | Image: Erect | An image that appears upright or in the same relative position as the object. [14] |
| 6394 | Index Mirror | The mirror attached to the index arm of a marine sextant. Also called index glass. [14] |
| 6395 | Island Shelf | See continental shelf. [14] |
| 6396 | Island Slope | See continental slope. [14] |
| 6397 | Kelvin Scale | A temperature scale with zero degrees equal to the theoretical temperature at which all molecular motion ceases. Also called the absolute scale. The units are sometimes called ?degrees kelvin?; however, the correct si terminology is ?kelvins,? Abbreviated k. [1] |
| 6398 | Kilogram(Me) | The unit of mass in the si system. [14] |
| 6399 | Lamp: Signal | A compact, portable battery-operated electric lamp used as a target for observations or surveys of high precision. The parabolical reflector is mounted in a special case so as to facilitate pointing and adjusting. [14] |
| 6400 | Lappened Ice | See anchor ice. [14] |
| 6401 | Leader Cable | See cable. [14] |
| 6402 | Leeward Tide | See tide. [14] |
| 6403 | Leeway Angle | The angle between true heading and track of a vessel caused by wind action. [14] |
| 6404 | Level: Dumpy | See levelling instrument: dumpy level. [14] |
| 6405 | Level: Plate | A spirit level attached to the plate of a surveying instrument for the purpose of levelling the graduated circle or, indirectly, making the vertical axis truly vertical. [14] |
| 6406 | Light Pencil | A bundle of light rays originating at, or directed to, a single point. [14] |
| 6407 | Light: Fixed | A signal light that shows continuously, in any given direction, with constant luminous intensity and colour. [14] |
| 6408 | Light: Front | See light(s): range. [14] |
| 6409 | Light: Point | A luminous signal appearing without perceptible length, as contrasted with a linear light. [14] |
| 6410 | Line Of Flow | The vector line showing the direction of current at a given time. Also called streamline. [14] |
| 6411 | Line Spacing | Distance between sounding lines. Spacing usually depends on the type of survey, the instruments used, and the demanded accuracy. [14] |
| 6412 | Linear Light | See light. [14] |
| 6413 | Linear Scale | See scale: bar. [14] |
| 6414 | Linear Speed | See speed. [14] |
| 6415 | Lock Gate(S) | Pair of massive hinged doors at each end of a lock. [14] |
| 6416 | Loop Antenna | A directional antenna consisting essentially of one or more complete turns of wire. [14] |
| 6417 | Macroclimate | The general climate of a large area, such as a country. [1] |
| 6418 | Magnetograph | A magnetic observatory instrument consisting of one or more (usually 3) variometers, one for each magnetic element recorded, and a recorder. [14] |
| 6419 | Major Planet | See planet. [14] |
| 6420 | Map: Contour | A topographic map which portrays relief by means of contours. [14] |
| 6421 | Marine Borer | Any marine invertebrate that excavates tunnels, holes, or depressions in one or more of a variety of materials by abrasive, chewing, or chemical action. [14] |
| 6422 | Marine Light | See light. [14] |
| 6423 | Meroplankton | Chiefly the floating development stages (eggs and larvae) of the benthos and nekton. [14] |
| 6424 | Microclimate | The climate structure of the air space near the surface of the earth. [1] |
| 6425 | Minor Planet | An asteroid. [14] |
| 6426 | Mixing Depth | The vertical extent of the mixing layer. [1] |
| 6427 | Mixing Layer | The unstable atmospheric layer that extends from the surface up to the base of an inversion. Within this layer, the air is well stirred. [1] |
| 6428 | Month: Lunar | See month: synodical. [14] |
| 6429 | Nadir Radial | See radial. [14] |
| 6430 | Natural Year | See year: tropical. [14] |
| 6431 | Navigability | Of a vessel: capability of being controlled and steered. Of a water area: capability of being navigated. [14] |
| 6432 | Neap Tide(S) | See tide. [14] |
| 6433 | Nimbostratus | A dark, gray cloud characterized by more or less continuously falling precipitation. It is rarely accompanied by lightning, thunder, or hail. [1] |
| 6434 | On Soundings | Said of a vessel navigating within the 100-fathom line. In earlier times, said of a vessel in water sufficiently shallow for sounding by hand lead. [14] |
| 6435 | Onshore Wind | Wind blowing from sea toward the land. See sea breeze. [14] |
| 6436 | Optical Flat | A surface, usually of glass, ground and polished plane within a fraction of a wavelength of light. An optical element or glass blank with an optical flat is used to test the flatness of other surfaces. [14] |
| 6437 | Optical Path | The path followed by a ray of light through an optical system. [14] |
| 6438 | Oscilloscope | A type of oscillograph that visually records an electrical wave on a fluorescent screen, as of a cathode-ray tube. [14] |
| 6439 | Ozalid Print | See print: ozalid. [14] |
| 6440 | Panchromatic | (Adj.). Sensitive to light of all colors, as a film or plate emulsion. [14] |
| 6441 | Parallax Bar | See stereometer. [14] |
| 6442 | Parallax: X- | See parallax: absolute stereoscopic. [14] |
| 6443 | Partial Node | The point, line, or surface, in a standing wave system where some characteristic of the wave field has a minimum amplitude differing from zero. [14] |
| 6444 | Photoalidade | A photogrammetric instrument having a telescopic alidade, a plateholder, and a hinged ruling arm mounted on a tripod frame. It is used for plotting lines of direction and measuring vertical angles to selected features appearing on oblique and terrestrial photographs. [14] |
| 6445 | Photocompose | (v.t.). To combine distinct parts of chart original by photographic processes. [14] |
| 6446 | Photogravure | A photoengraving process by which photographs or textual matters are reproduced on intaglio printing plate or rolls from which they may be transferred to paper. [14] |
| 6447 | Pigmentation | A colouring of tissue by deposition of pigments. [14] |
| 6448 | Pileus Cloud | A smooth cloud in the form of a cap. Occurs above, or is attached to, the top of a cumuliform cloud. Also called a cap cloud. [1] |
| 6449 | Pressure Ice | A general term for floating ice which has been squeezed together and in places forced upwards, when it can also be described as rafted ice, hummocked ice, pressure ridge, tented ice. [14] |
| 6450 | Print: Ratio | A print in which the scale has been changed from that of the negative or transparency by projection printing. [14] |
| 6451 | Pulse Length | The time interval during which the amplitude of a pulse is at or greater than a specified value, usually stated in terms of a fraction or percentage of the maximum value. [14] |
| 6452 | Reflectivity | The ratio of the radiant energy reflected by a surface to that incident upon it. [14] |
| 6453 | Reproducible | An original drawing, photographic positive or negative on stable base material to be used in the process of reproduction. [14] |
| 6454 | Reticle Ring | The ring across which the system of wires, hairs, threads, or the like of a reticle are stretched; or the ring which supports the glass diaphragm when the reticle is a system of lines etched on glass. [14] |
| 6455 | Rise Of Tide | The height of high water above datum. Also called tidal rise. [14] |
| 6456 | Scale Factor | A multiplier for reducing a distance obtained from a map by computation or scaling to the actual distance on the datum of the map. A conventional modification which may be applied to the majority of map projections. This is the multiplication of the principal scale by some numerical con-stant which is slightly less than unity. This has the effect of changing all particular scales by a corre-sponding amount and, since both maximum and minimum particular scales are similarly modified, the special properties of the projection are unaffected. The effect is to produce a better balance of positive and negative scale errors over the mapped area. [14] |
| 6457 | Scale: Large | A scale involving a relatively small reduction in size. A large scale chart is one covering a small area. The opposite is small scale. See scale: natural. [14] |
| 6458 | Scale: Small | A scale involving a relatively large reduction in size. A small scale chart is one covering a large area. The opposite is large scale. See scale: natural. [14] |
| 6459 | Scale: Speed | A graphic scale by means of which the rate of speed of a survey ship, or the distance travelled in a given time can be determined quickly and accurately. [14] |
| 6460 | Sextant: Air | A sextant designed primarily for air navigation. Air sextants are generally provided with some form of artificial horizon. [14] |
| 6461 | Signal: Tide | A signal or message conveying information on tidal conditions in the area in question. [14] |
| 6462 | Signal: Time | An accurate signal marking a specified time or time interval. It is used primarily for determining errors of timepieces. Such signals are usually sent from an observatory by radio or telegraph, but visual signals are used at some ports. [14] |
| 6463 | Snapper: Mud | A small clamshell snapper which is attached to the bottom of sounding lead by means of a hole drilled in the lead. [14] |
| 6464 | Snow Pellets | White, opaque, approximately round ice particles between 2 and 5 mm in diameter that form in a cloud either from the sticking together of ice crystals or from the process of accretion. Also called graupel. [1] |
| 6465 | Sonar Target | An object which reflects a sufficient amount of a sonar signal to produce a detectable echo signal at the sonar equipment. [14] |
| 6466 | Spectroscope | An optical instrument for forming spectra. It is very useful in studying the characteristics of celestial bodies. [14] |
| 6467 | Stadia Wires | See stadia lines. [14] |
| 6468 | State Of Sky | State of the atmosphere in respect of the amount, genus, height, etc. Of the clouds which are present. [14] |
| 6469 | Station Buoy | A buoy used to mark the approximate position of an important buoy or lightship should it be carried away or temporarily removed. Also called marker buoy, watch buoy. [14] |
| 6470 | Statute Mile | A unit of distance equal to 1,760 yards or 5,280 feet (1,609.35 m). This mile is generally used on land, and is sometimes called land mile. [14] |
| 6471 | Surface Duct | A zone immediately below the sea surface where sound rays are refracted toward the surface and then reflected. They are refracted because the sound velocity at some depth near the surface is greater than at the surface. The rays alternately are refracted and reflected along the duct to considerable distances from the sound source. [14] |
| 6472 | Survey: Land | See survey: cadastral. [14] |
| 6473 | Taffrail Log | See log. [14] |
| 6474 | Tartan Plots | Lattices resulting from the enlargement of small parts of two range and hyperbolic lattices, used for work which has to be carried out on a scale larger than that being used for the main survey. [14] |
| 6475 | Thematic Map | See map. [14] |
| 6476 | Thermosphere | The atmospheric layer above the mesosphere (above about 85 km) where the temperature increases rapidly with height. [1] |
| 6477 | Tide: Rising | The portion of the tide cycle between low water and the following high water. Also called flood tide. The opposite is falling tide. [14] |
| 6478 | Tide: Syzygy | The tide which takes place on the afternoon of the day the sun and moon are in syzygy. (this term is now little used). [14] |
| 6479 | Tide: Tropic | The tide that occurs twice monthly when the effect of the moon's maximum declination north or south of the equator is greatest. [14] |
| 6480 | Time: Summer | See time: daylight saving. [14] |
| 6481 | Tinted Areas | Those areas on the nautical chart that are symbolized by a flat colour to indicate the nature of the area. [14] |
| 6482 | Topmark Buoy | A buoy with a top mark, or characteristic shape secured at the top to aid in its identification. [14] |
| 6483 | True Bearing | See bearing. [14] |
| 6484 | Trumpet Buoy | See buoy: sound. [14] |
| 6485 | Turning Buoy | A buoy marking a turn, as in a channel. [14] |
| 6486 | Undercurrent | A current below the surface, particularly one flowing in a direction or at a speed differing from the surface current. [14] |
| 6487 | Uniform Flow | Any current in which neither convergence nor divergence is present. [14] |
| 6488 | Veering Wind | Clock-wise change of wind direction, in either hemisphere. [14] |
| 6489 | Venturi Tube | The trade name for a short tube of smaller diameter in the middle than at the ends. When a fluid flows through such a tube, the pressure decreases as the diameter becomes smaller, the amount of the decrease being proportional to the speed of flow and the amount of restriction. [14] |
| 6490 | Volcanic Ash | Uncemented pyroclastic material consisting of fragments mostly under 4 millimeters in diameter. Coarse ash is 1/4 to 4 millimeters in grain size; fine ash is below 1/4 millimeter. A constituent of some marine sediments. [14] |
| 6491 | Warping Buoy | A buoy so located that lines to it can be used for the movement of ships. [14] |
| 6492 | Water Signal | See signal. [14] |
| 6493 | Wave Cyclone | An extratropical cyclone that forms and moves along a front. The circulation of winds about the cyclone tends to produce a wavelike deformation on the front. [1] |
| 6494 | Wave: Direct | A subdivision of the space wave component of the electromagnetic ground wave. This wave is propagated directly through space, i.e., it follows the shortest path between transmitter and receiver. [14] |
| 6495 | Wave: Forced | A wave generated and maintained by a continuous force, in contrast to a free wave that continues to exist after the generating force has ceased to act. [14] |
| 6496 | Wave: Ground | That portion of a radio wave in proximity to and affected by the ground, being somewhat refracted by the lower atmosphere, diffracted by the surface of the earth and retarded by the resistivity of the earth. Such a wave travels more or less parallel to the surface of the earth. See wave: sky. [14] |
| 6497 | Weather Buoy | An ocean data acquisition system (ODAS) used for collecting oceanographic or meteorological information. ODAS’s buoys are up to 40 feet in diameter. [14] |
| 6498 | Weather Side | The side of a vessel toward which, or the side of a channel from which the wind is blowing. [14] |
| 6499 | Weather Vane | See vane. [14] |
| 6500 | Wind Turbine | A tower and associated equipment that generates electrical power from wind. They can be sited offshore and may be either fixed or floating. [14] |
Notes:
(v.t) : Verb Transitive
(v.i.) : Verb Intransitive
References:
[1] Ahrens, C. D. (2008). Essentials of Meteorology: An invitation to the atmosphere. Andover: Cengage Learning.
[2] Hydrographic Dictionary Working Group. (2019). S-32 IHO Hydrographic Dictionary. IHO Publications
[3] American Meteorological Society (2020). Geostrophic Current. Glossary of Meteorology, http://glossary.ametsoc.org/wiki/climatology. (access 25February2021)
[4] American Meteorological Society (2020). Return Period. Glossary of Meteorology, http://glossary.ametsoc.org/wiki/climatology. (access 25February2021)
[5] American Meteorological Society (2020). Surface Current. Glossary of Meteorology, http://glossary.ametsoc.org/wiki/climatology. (access 25February2021)
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