- Industri: 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, ...
The theoretical phase of a constituent of the equilibrium tide. It is usually represented as the sum of two angles V and u, in which V is a uniformly and rapidly changing angle involving multiples of the hour angle of the mean Sun, mean longitudes of the Sun and Moon, and mean longitude of the lunar or solar perigee. u is a slowly changing angle depending on the longitude of the ascending node of the Moon's orbit.
Industry:Earth science
A bar or block whose ends or sides are flat and contain a defined or otherwise known length between them. The ends are usually optically flat (i.e., flat to within a fraction of a wavelength of light) and polished to a mirror like finish so that the length can be measured interferometrically.
Industry:Earth science
An equation which represents a balance between the horizontal difference of pressure, in a fluid, and the Coriolis force per unit area. The equation used to compute the speed of the current is v = κ (D <sub>a</sub> - D <sub>b</sub>) n/ L, in which D <sub>a</sub> and D <sub>b</sub> are the dynamic height anomalies at stations a and b, respectively; n is a unit distance conversion factor, L is the distance between stations a and b, v is the speed of the current and κ is defined as 1/(2 ω sin φ), in which ω is the Earth's rate of rotation and φ is the latitude.
Industry:Earth science
An ephemeris, of a celestial body in the Solar System, in which the tabulated positions are directly comparable to the mean places of stars listed in catalogs for some standard epoch. An astrometric position is obtained by adding to the geometric position, calculated from gravitational theory, the correction for light time and the E terms of annual aberration.
Industry:Earth science
(1) The act or right of going from a place of real or seeming confinement. (2) A place or means of exit; an outlet. (3) The emergence of a celestial body from eclipse, occultation, or transit.
Industry:Earth science
A scribing device that permits selection of uniformly spaced ticks in subdividing or putting ticks on graticules or maps.
Industry:Earth science
A great circle, on the celestial circle, in the plane of the Moon's equator i.e., in a plane perpendicular to the Moon's axis of rotation.
Industry:Earth science
That portion of the total potential energy which can be converted to kinetic energy in an adiabatically enclosed system.
Industry:Earth science
The quantity rH(r+H), in which r is the radius of the Earth at 45<sup>o</sup> 32' 40" latitude and H is the dynamic height in dynamic meters.
Industry:Earth science
The unit of time equal to 1/(31 556 925. 974 7) part of the tropical year for 1900 January 0 at 12 hours ephemeris time. This definition was adopted in 1960 by the general Conference on Weights and Measures, the previous definition in terms of the rotation of the Earth being abolished. It is theoretically equivalent to the system of time used by Simon Newcomb in his theory of the motions of the Solar System. The ephemeris second was replaced, in 1967, by the atomic second.
Industry:Earth science
