- Industry: Earth science
- Number of terms: 93452
- Number of blossaries: 0
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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, ...
(1) A set of aerial photographs completely depicting a region, having stereoscopic overlap between exposures along the line of flight and sidelap between photographs on adjacent lines of flight. (2) A set of aerial photographs, for each of which recorded SHORAN distances at the time of exposure are available. (3) A set of images or other graphic material completely depicting a region.
Industry:Earth science
A horizontal movement of water caused by motion of the Earth in the gravitational fields of the other members of the Solar System. More particularly, it is the horizontal component of the particular motion of a tidal wave. It is part of the same general movement of the sea which is manifested in the vertical rise and fall of the waters.
Industry:Earth science
A curve which gives the standard deviation in any arbitrary direction. It is tangent to the error ellipsoid at the ends of the major and minor axes, and bows outward at intermediate points.
Industry:Earth science
(1) The process of applying, to a measured or calculate value of gravity, the sum δ <sub>c</sub> of the following gravity corrections in the order listed: (a) the condensation gravity correction δg <sub>c</sub>; (b) the free air gravity correction δg <sub>f</sub>; and (c) the cylindrical Bouguer gravity correction δg <sub>Bc</sub>. The advantage of the condensation gravity reduction over, e.g., the Bouguer gravity reduction, is that the former changes the location of the geoid (or other reference surface) by less than 3 meters, whereas the Bouguer gravity reduction may change that surface's location by hundreds of meters. (2) The same as the previous definition but with a topographic gravity correction added and with the condensation gravity correction modified to allow for the effect of topography. (3) The quantity δ <sub>c</sub> defined in the first definition. (4) The sum of the gravity corrections applied according to the second definition. The condensation gravity reduction is also called Faye's gravity reduction and the Helmert gravity reduction.
Industry:Earth science
The amount of energy received, on a planet or satellite, per unit area per unit time from the Sun, at the average distance of that planet or satellite from the Sun. In particular, the amount of energy received at the Earth per unit area per unit time from the Sun, at the average distance of the Earth from the Sun (i.e., at the distance of one astronomical unit). A well determined average value (1982) for the Earth's solar constant is 1368 watts/meter² ± 0. 2%. The actual value of the energy varies by about 7% between aphelion and perihelion.
Industry:Earth science
A corner at the intersection of a surveyed boundary with a previously established boundary line. In surveying the public lands of the USA, when the line connecting the last section corner and the corner to be reached on an established township boundary departs from the astronomic meridian by more than the allowable amount, the line being surveyed is extended in a cardinal direction to an intersection with the township boundary, where a closing corner is established and a connection made to the previously established corner. A closing corner is established at the intersection of a line being surveyed with a previously established township boundary to avoid excessive deviation from a cardinal direction which might be required to connect with the intended corner on that boundary. A closing corner is also established at the intersection of a township, range, or section line with the boundary of a previously surveyed and segregated tract of land such as a private land claim, mineral claim, etc.
Industry:Earth science
The quantity subtracted from a distance measured, using radio waves, between a point on the surface and a point in or above the ionosphere, to obtain the distance that would have been measured had the ionosphere not been present. The correction is significant for distances measured using radio waves having frequencies lower than about 0. 9 GHz, e.g., for distances measured using the radio waves emitted by TRANSIT satellites (150 MHz and 400 MHz).
Industry:Earth science
The quantity 2Ω cos φ', where Ω is the Earth's rate of rotation and φ' is the geocentric latitude. It is usually denoted by f and has a value of about 0. 0001/s in mid latitudes.
Industry:Earth science
A solar day beginning at midnight. The civil day may be based either on apparent solar time or on mean solar time. It begins 12 hours earlier than the astronomical day of the same date.
Industry:Earth science
A rectangular, Cartesian coordinate system in a plane tangent to the celestial sphere at the point to which the optical axis of a telescope is directed. The positive η axis points towards the north pole and the positive ξ axis points eastward.
Industry:Earth science
