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Azimuth is measured eastward from the north point (sometimes from the south point) of the horizon; altitude is the angle above the horizon. The horizontal coordinate system is a celestial coordinate system that uses the observer's local horizon as the fundamental plane to define two angles of a spherical coordinate system: altitude and azimuth.
Pressure altitude is the elevation above a standard datum air-pressure plane (typically, 1013.25 millibars or 29.92" Hg). Pressure altitude is used to indicate "flight level" which is the standard for altitude reporting in the U.S. in Class A airspace (above roughly 18,000 feet).
Even with these restrictions, if the polar angle (inclination) is 0° or 180°—elevation is −90° or +90°—then the azimuth angle is arbitrary; and if r is zero, both azimuth and polar angles are arbitrary. To define the coordinates as unique, the user can assert the convention that (in these cases) the arbitrary coordinates are set to zero.
The azimuth is the angle between the north vector and the star's vector on the horizontal plane. [2] Azimuth is usually measured in degrees (°), in the positive range 0° to 360° or in the signed range -180° to +180°. The concept is used in navigation, astronomy, engineering, mapping, mining, and ballistics.
The solar azimuth angle is the azimuth (horizontal angle with respect to north) of the Sun's position. [1] [2] [3] This horizontal coordinate defines the Sun's relative direction along the local horizon, whereas the solar zenith angle (or its complementary angle solar elevation) defines the Sun's apparent altitude.
Geodetic latitude and geocentric latitude have different definitions. Geodetic latitude is defined as the angle between the equatorial plane and the surface normal at a point on the ellipsoid, whereas geocentric latitude is defined as the angle between the equatorial plane and a radial line connecting the centre of the ellipsoid to a point on the surface (see figure).
The bearing angle value will always be less than 90 degrees. [1] For example, if Point B is located exactly southeast of Point A, the bearing from Point A to Point B is "S 45° E". [ 3 ] For example, if the bearing between Point A and Point B is S 45° E, the azimuth between Point A and Point B is 135°.
It is the complement to the solar altitude or solar elevation, which is the altitude angle or elevation angle between the sun’s rays and a horizontal plane. [1] [2] At solar noon, the zenith angle is at a minimum and is equal to latitude minus solar declination angle. This is the basis by which ancient mariners navigated the oceans. [3]