Free to Access Metocean Glossary
Summary of Metocean Terms from Various Source by BW Geohydromatics
(SC | 05/05/2021)
With the increasing need for industry to understand the terms frequently used in the world of meteorology and oceanography (metocean), BW Geohydromatics launched the Metocean Glossary which can be accessed for free. The experience of BW Geohydromatics, a dozen years of consultancy in the metocean field, is condensed in a Glossary designed to optimize support to the industry.
This glossary is a reference dictionary of hydrographic terms used in various standards, specifications, and other information frequently used by the maritime industry. Here you can find more than 6,500 easy-to-understand descriptions of meteorological and oceanographic terms.
With this Glossary, the industry, especially our clients, will be made easy to understand Metocean’s scientific terms which sometimes also have many confusing acronyms.
Please visit https://bwgeohydromatics.com/metocean-glossary/ and do let us know if you have benefited from this Glossary.
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Glosarium Metocean
Rangkuman Istilah dalam Dunia Metocean dari Berbagai Sumber oleh BW Geohydromatics
Dengan meningkatnya kebutuhan industri untuk memahami istilah yang sering dipakai di dunia meteorologi dan oseanografi (metocean), BW Geohydromatics meluncurkan Glosarium Metocean yang dapat diakses secara gratis. Pengalaman BW Geohydromatics, yang selama belasan tahun menjadi konsultan di bidang metocean, dipadatkan dalam Glosarium yang dirancang untuk mengoptimalkan dukungan kepada industri.
Glosarium ini adalah kamus referensi istilah terkait hidrografi yang digunakan dalam berbagai standar, spesifikasi, dan informasi lain yang sering digunakan industri maritim. Di sini dapat ditemukan lebih dari 6500 penjelasan istilah meteorologi dan oseanografi yang mudah untuk dipahami.
Dengan Glosarium ini, dunia industri, terutama para klien, akan sangat dimudahkan dalam memahami istilah Metocean yang ilmiah dan memiliki banyak akronim.
Silakan kunjungi https://bwgeohydromatics.com/metocean-glossary/ dan mohon beri tahu kami jika Anda memperoleh manfaat dari Glosarium ini.
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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.
Please use the relevance 2-3 words from the desired term to get the best result from our search feature.
Example: to find HAT refering to Tidal Level, please type “HAT Tidal Level” in the search box:
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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] |