- Industry: Earth science
- Number of terms: 93452
- Number of blossaries: 0
- Company Profile:
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, ...
The angular motion of a star relative to other stars.
Industry:Earth science
A map showing the structure and mineralogical composition of the Earth's crust.
Industry:Earth science
A satellite (of the Earth) constructed and put into orbit as a beacon for use in navigation.
Industry:Earth science
The art of navigating in oceanic regions by determining the vessel's location with respect to known locations of geological features on the bottom. This method is particularly useful to submarines; it is valueless to most surface vessels.
Industry:Earth science
The average, semidiurnal difference in the height of the water at the time of quadrature. Mean neap range is smaller than the mean range where the tide is either semidiurnal or mixed, and is of no practical significance where the tide is diurnal.
Industry:Earth science
A hyperbolic navigation system for measuring differences between distances from a radio receiver to three or more fixed transmitters of known geographic location. One type of Loran operates in a narrow band about 2 MHz; another in a narrow band about 100 kHz. The receiver's location is found to lie on a particular hyperbola like curve on the ellipsoid by measuring the difference in times of arrival of pulses sent synchronously from a single pair of transmitters. This curve is one of the two loci of all points whose distances from the two stations differ by the linear equivalent of the time interval measured. By measuring the time interval using a different pair of stations, a second hyperbola-like curve is determined. The receiver is therefore located at the intersection of these two curves. Note that each difference actually determines a pair of hyperbolas (i.e., a complete hyperbola of two branches.) However, one branch is usually too far distant from the approximately known location of the receiver to need consideration. Furthermore, it is usually on land.
Industry:Earth science
The area of a flat surface bounded by a square 1 mile on a side. This unit is now used almost entirely by the USA. In using it, care must be taken to specify whether the nautical mile or the statute mile is meant. A square (statute) mile is equal to approximately 2.589988 square kilometers or 58.9988 hectares; it is equal exactly to 240 acres or
Industry:Earth science
(1) The vertical-control datum used (1980 and later) by the National Geodetic Survey for vertical control. (2) In the form National Geodetic Vertical Datum of 1929, a synonym for Sea level Datum of 1929. This term was officially adopted by the National Geodetic Survey on 17 May 1976.
Industry:Earth science
A measuring engine having binocular optics creating a stereoscopic image from stereoscopic pair of photographs and allowing the operator to determine coordinates in a three-dimensional, rectangular, Cartesian coordinate system.
Industry:Earth science
(1) The dihedral angle between two planes perpendicular to a common plane of reference through the center of an ellipsoid, the one plane serving as a reference and the other containing the normal at the point whose longitude is desired. The angle is positive taken clockwise from the plane of reference. (2) The difference between the values assigned two lines representing, on a graticule, meridians on an ellipsoid; the one line is taken as reference and the other is the one representing the meridian through the point in question. (3) The arc, on a great circle denoted the fictitious equator, between two great circles passing through the poles of the fictitious equator, one of the great circles serving as a meridian of reference (fictitious prime meridian) and the other as a local meridian (fictitious meridian). A fictitious longitude may be called a grid longitude, oblique longitude or transverse longitude according as the fictitious equator is a line on a grid or is a great circle oblique or transverse to the actual equator.
Industry:Earth science
