- Industry: 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, ...
Referring to a characteristic of a surrounding medium e.g., ambient pressure, ambient temperature.
Industry:Earth science
A conformal map projection mapping a sphere or hemisphere into a rhombus having one opposite pair of angles equal to 60° and the other pair equal to 120°. The complex function z(x + iy) is related to longitude <font face = symbol>l</font> and latitude <font face = symbol>f</font> on the sphere by w(z) = (tan (1/4 (<font face = symbol>p</font>- 2<font face = symbol>f</font>)) ei <font face = symbol>l</font>)<sup>1/3</sup>, in which w(z) is the elliptical function defined by z = ∫ (1 - w <sup>3</sup>)<sup>-2/3</sup> dw. The map projection was used by J. S. Cahill for one version of his butterfly map. It is related to ë and ö on the hemisphere by u(z) = w ²(z), where u(z) is substituted for w(z) in the integral defining z. The poles will be at the apices of the 120° angles.
Industry:Earth science
An astrolabe consisting of a telescope with a prism and artificial horizon attached at its objective end so that only objects near one specific angular elevation can be observed. The usual form of this instrument has a horizontal telescope and contains a 60° prism, with the face nearest the objective being perpendicular to the line of collimation of the telescope, and a small pool of mercury attached beneath the prism to give an artificial horizon. In observing, two images of a star are seen. One image has been reflected directly into the telescope by the lower face of the prism. The other has been reflected first by the mercury's surface and then into the telescope by the upper face of the prism. The two images move in opposite directions either to or from coincidence. At the instant of coincidence, the star is at the apparent angular elevation imposed by the prism's angle. Prismatic astrolabes may be made with the angle at other that 60°. An English instrument uses a prism with 45° angle and has accessories.
Industry:Earth science
The line following the sinuosities of the low-water mark, except where indentations are encountered that fall within the category of true bays, when the base line becomes a straight line between headlands.
Industry:Earth science
The angle, at the point of observation, between the vertical plane through the observed object and the vertical plane in which a freely suspended, sym-metrically magnetized needle, influenced by no transient or artificial magnetic disturbance, will come to rest. (187) Magnetic azimuth is generally reckoned from magnetic north (0°) clockwise through 360°. Such an azimuth should be marked as being magnetic, and the date of its applicability be given.
Industry:Earth science
(1) The angle between the direction in which a craft is moving and the longitudinal axis of the craft. (2) The angle between the projection, onto a horizontal plane, of the direction in which a craft is moving the projection, onto the same plane, of the longitudinal axis of the craft. The angle is usually small enough that either of the definitions gives the same angle within the tolerances allowed by the situation. (3) The angle through which a coordinate system fixed in a photograph must be rotated about the z-axis in object space to make the x-axis and y-axis of the photograph parallel to the x-axis and y-axis in object space. Yaw is usually the tertiary rotation, preceded by pitch and roll, so that the photograph's z-axis is presumed already to have been made parallel to the z-axis in object space. (4) The angle through which a coordinate system fixed in a photograph is rotated about a specified line through the origin of the coordinate system and nearly perpendicular to the photograph. The angle is measured in a plane perpendicular to the specified axis of rotation between a specified line in that plane and the projection of the x axis of the coordinate system of the photograph onto that plane. In all the above definitions, the angle, also called crab is usually denoted by <sub>k</sub> and called kappa.
Industry:Earth science
(1) An angle (figure) formed by the intersection of segments of two curves on a spheroid. The two segments are called the sides of the spheroidal angle and the point of intersection is called the vertex. (2) A number indicating the rate at which the sides of the spheroidal angle (f) diverge in the neighborhood of the vertex, and defined to be the plane angle between the tangents to the two segments at the vertex.
Industry:Earth science
The angle between the optical axes of any two rigidly connected cameras. Also, in particular, the angle between the optical axes of the vertical and oblique cameras of a multi camera system, or the angle between the planes of the vertical and oblique photographs.
Industry:Earth science
The state of stratification of a fluid in which surfaces of constant pressure coincide with surfaces of constant density. It is the state of zero baroclinicity.
Industry:Earth science
