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[5] [6] At a given location during the course of a day, the Sun reaches not only its zenith but also its nadir , at the antipode of that location 12 hours from solar noon . In astronomy , the altitude in the horizontal coordinate system and the zenith angle are complementary angles , with the horizon perpendicular to the zenith.
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. Therefore, the horizontal coordinate system is sometimes called the az/el system, [1] the alt/az system, or the alt-azimuth system, among
ICAO further defines: elevation: "the vertical distance of a point or a level, on or affixed to the surface of the earth, measured from mean sea level." [2] I.e., elevation would be the altitude of the ground or a building.
A-type star In the Harvard spectral classification system, a class of main-sequence star having spectra dominated by Balmer absorption lines of hydrogen. Stars of spectral class A are typically blue-white or white in color, measure between 1.4 and 2.1 times the mass of the Sun, and have surface temperatures of 7,600–10,000 kelvin.
The angle of a celestial body with the zenith is the zenith angle (in astronomy, commonly referred to as the zenith distance).A body's angular position can also be given in terms of altitude, the angle above the geometric horizon; the altitude and the zenith angle are thus related by =.
The rate of decrease of temperature with elevation is known as the adiabatic lapse rate, which is approximately 9.8 °C per kilometer (or 5.4 °F [3.0 °C] per 1000 feet) of altitude. [ 12 ] The presence of water in the atmosphere complicates the process of convection.
One sidereal hour (approximately 0.9973 solar hours) later, Earth's rotation will carry the star to the west of the meridian, and its hour angle will be 1 h. When calculating topocentric phenomena, right ascension may be converted into hour angle as an intermediate step. [11] [12] [13]
Elevation (ballistics), the angle between a weapon barrel and the horizontal plane Elevation (astronomy), one component of the horizontal coordinate system Elevation (view), used in architectural drawing to represent a building facade