- Sektör: Earth science
- Number of terms: 93452
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Founded in 1941, the American Congress on Surveying and Mapping (ACSM) is an international association representing the interests of professionals in surveying, mapping and communicating spatial data relating to the Earth's surface. Today, ACSM's members include more than 7,000 surveyors, ...
A unit of brightness in monochromatic radiation of frequency v, being the brightness of an object at a distance of 1 parsec and emitting as much energy in the decade of frequency centered at v as the Sun does at all wavelengths (frequencies). The unit was proposed in 1982 by M. Disney and W. Sparks. It is numerically equal to 3.198 x10 <sup>-5</sup> ergs per sq. Cm per second per decade of frequency about v. Sirius has a brightness of 5.9 Herschels at about 106 GHz (i.e., in visible light)
Industry:Earth science
A station at which measurements are made to determine the value of gravity.
Industry:Earth science
A chronometer observed visually for meeting the schedule of observations, making routine settings of instruments, etc., but not usually used as an accurate source of time or source of recorded time.
Industry:Earth science
A method of network adjustment in which the network is broken up into a hierarchy of smaller and smaller networks. The smallest members of the hierarchy are adjusted first; these adjusted members are then combined by means of common points into next larger members, and these are then adjusted, and so on. The process continues until the entire network has been adjusted. The final result is the same as that which would result from a simultaneous least squares adjustment of the entire network but needs a much smaller computer for the calculation. Helmert blocking is a special form of solving a system of simultaneous linear equations by partitioning the normal matrix, the observations and unknowns being partitioned on a geographical basis. It is therefore particularly applicable to the solving the large, sparse systems of equations typical of large geodetic networks. It was used for the re adjustment (1979) of the European triangulation and (1983-1985) for re adjusting the North American triangulation.
Industry:Earth science
A stereoscopic instrument similar to a range finder but constructed to give heights rather than slant range (distance along the line of sight)
Industry:Earth science
Measured value of gravity reduced to the value it would have on the geoid or some other reference surface, using one of the procedures for gravity reduction.
Industry:Earth science
(1) The science dealing with the physical features (geometry and dynamics) of the surface waters of the Earth. Hydrography differs from physical oceanography in that it deals with rivers and lakes as well as with oceans and seas. It differs from hydrology in dealing with only surficial waters and not with underground waters. (2) The science dealing with the geometric features of the surface waters of the Earth. In this sense, the term is practically synonymous with charting. (3) The science dealing with the surface waters of the Earth. This appears to be the term's original meaning. However, present custom is to use the term oceanography instead, if marine waters are being considered and hydrology if rivers, lakes, etc., are being considered also. (4) That branch of physical oceanography dealing with the measurement and definition of the configuration of the bottoms and adjacent land regions of oceans, lakes, rivers, harbors and other forms of water on the Earth. (5) The science and art of measuring the oceans, seas, rivers, and other waters, with their marginal lands, inclusive of all the fundamental elements which have to be known for the safe navigation of such regions, and the publication of such information in a form suitable for the use of navigators. This definition resembles definition (2) but is much less general in that it excludes all subjects not concerned with navigation or concerned with navigation but not published. It does include measurement of marginal land, however. (6) That science which deals with the measurement and description of the physical features of the oceans, seas, lakes, rivers and their adjoining coastal regions, with particular attention to the use for navigational purposes.
Industry:Earth science
A set of linear formulas giving the small changes in azimuth, latitude, and longitude which take place in a geodetic network when the dimensions and orientation of the rotational ellipsoid carrying the network are changed.
Industry:Earth science
(1) The amount or proportion of moisture in a gas; the degree of wetness of a gas. (2) The amount or proportion of moisture in the atmosphere; the degree of wetness of the atmosphere.
Industry:Earth science
