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  2. Zenith - Wikipedia

    en.wikipedia.org/wiki/Zenith

    In astronomy, the altitude in the horizontal coordinate system and the zenith angle are complementary angles, with the horizon perpendicular to the zenith. The astronomical meridian is also determined by the zenith, and is defined as a circle on the celestial sphere that passes through the zenith, nadir, and the celestial poles .

  3. Air mass (astronomy) - Wikipedia

    en.wikipedia.org/wiki/Air_mass_(astronomy)

    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 =.

  4. Altitude - Wikipedia

    en.wikipedia.org/wiki/Altitude

    The stratosphere is also the altitude limit of jet aircraft and weather balloons, as the air density there is roughly 1 ⁄ 1000 of that in the troposphere. [1] Vertical distance comparison The term altitude can have several meanings, and is always qualified by explicitly adding a modifier (e.g. "true altitude"), or implicitly through the ...

  5. Horizontal coordinate system - Wikipedia

    en.wikipedia.org/wiki/Horizontal_coordinate_system

    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

  6. Vertical position - Wikipedia

    en.wikipedia.org/wiki/Vertical_position

    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.

  7. Spherical coordinate system - Wikipedia

    en.wikipedia.org/wiki/Spherical_coordinate_system

    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.

  8. Solar zenith angle - Wikipedia

    en.wikipedia.org/wiki/Solar_zenith_angle

    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]

  9. Hour angle - Wikipedia

    en.wikipedia.org/wiki/Hour_angle

    The cosine of the hour angle (cos(h)) is used to calculate the solar zenith angle. At solar noon, h = 0.000 so cos(h) = 1, and before and after solar noon the cos(± h) term = the same value for morning (negative hour angle) or afternoon (positive hour angle), so that the Sun is at the same altitude in the sky at 11:00AM and 1:00PM solar time. [5]