English

The angular drawing together of the GEOGRAPHIC MERIDIANS in passing from the EQUATOR to the POLES. The difference between the two angles formed by the intersection of a GREAT CIRCLE with two MERIDIANS. The difference between the RECIPROCAL BEARINGS of two points. At any point of a cartographic PROJECTION, the angle between the MERIDIAN, as represented on the plane of the PROJECTION and GRID in use, and the GRID NORTH line.

In OCEANOGRAPHY, region of CONVERGENCE. The region in the deep OCEAN where SOUND RAYS, refracted from the DEPTHS, arrive at the surface in successive intervals of 30 to 35 NAUTICAL MILES.

That factor by which the numerical value made in one system of units must be multiplied to arrive at the numerical value in another system of units.

Any set of COORDINATES used to define a point on the CELESTIAL SPHERE. The HORIZON, CELESTIAL EQUATOR and ECLIPTIC SYSTEMS of celestial coordinates are based on the CELESTIAL HORIZON, CELESTIAL EQUATOR and ECLIPTIC respectively, as the PRIMARY GREAT CIRCLE.

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.

COORDINATES that define the POSITION of a point with respect to the centre of the EARTH. See LATITUDE: GEOCENTRIC. The term 'geocentric longitude' is never used, as the quantity which it would designate is the same as GEODETIC LONGITUDE.

Quantities which define the horizontal POSITION of a point on the SPHEROID OF REFERENCE with respect to the planes of GEODETIC EQUATOR and of a selected GEODETIC MERIDIAN. See LATITUDE: GEODETIC and LONGITUDE: GEODETIC.

A plane rectangular coordinate system based on, and mathematically adjusted to, a MAP PROJECTION, so that GEOGRAPHIC POSITIONS in terms of LATITUDE and LONGITUDE can be readily transformed into PLANE COORDINATES, and the computation relating to them made by the ordinary methods of PLANE SURVEYING.

The point of intersection of the COORDINATE AXES, from which the COORDINATES are reckoned. In mathematical treaties, this ORIGIN is usually given the COORDINATES 0,0; in SURVEYING, however, it is standard practice to give this ORIGIN, COORDINATES having large positive numerical values, thereby avoiding the use of negative COORDINATES. Also called point of origin. See COORDINATES: FALSE.

The distance and DIRECTION from a central point of reference to a point whose POSITION is being defined. The point of reference is termed the POLE or ORIGIN; the line (distance) connecting the ORIGIN with the point whose POSITION is being defined is the radius vector; and the angle between the fixed line (POLAR AXIS) which the DIRECTION is referred to and the radius vector is the vectorial angle.