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  2. Horizontal coordinate system - Wikipedia

    en.wikipedia.org/wiki/Horizontal_coordinate_system

    Altitude (alt.), sometimes referred to as elevation (el.) or apparent height, is the angle between the object and the observer's local horizon. For visible objects, it is an angle between 0° and 90°. [b] Azimuth (az.) is the angle of the object around the horizon, usually measured from true north and increasing eastward.

  3. Altitude - Wikipedia

    en.wikipedia.org/wiki/Altitude

    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).

  4. Geodetic coordinates - Wikipedia

    en.wikipedia.org/wiki/Geodetic_coordinates

    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).

  5. Azimuth - Wikipedia

    en.wikipedia.org/wiki/Azimuth

    The azimuth is the angle formed between a reference direction ... sometimes called elevation above the horizon. ... east has azimuth 90°, south 180°, and west 270

  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. Polar distance (astronomy) - Wikipedia

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

    An object on the celestial equator has a PD of 90°. Polar distance is affected by the precession of the equinoxes . If the polar distance of the Sun is equal to the observer's latitude , the shadow path of a gnomon 's tip on a sundial will be a parabola ; at higher latitudes it will be an ellipse and lower, a hyperbola .

  8. 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.

  9. Rayleigh sky model - Wikipedia

    en.wikipedia.org/wiki/Rayleigh_sky_model

    The scattering angle at an altitude of 45° is consistent. The input stokes parameters q and u are then with respect to North but in the altitude-azimuth frame. We can easily unwrap q assuming it is in the +altitude direction. From the basic definition we know that +Q is an angle of 0° and -Q is an angle of 90°.