© John Fowler
Placitas, New Mexico, United States of America
Latitude: 35° 18' 59'' N
Longitude: 106° 27' 0'' W
16 September 2013 1917 (Local Time)
Camera direction: towards E
Image P/S code: P.13.11.4.4
Image I.D.: 3974
Sometimes dark bluish streaks and light beams are observed radiating from the Sun across the twilight sky. The streaks are the shadows of clouds at or below the horizon and are called crepuscular rays. Occasionally, the beams and shadows may cross the sky, becoming visible again at the antisolar point. These rays, converging in the sky opposite to the Sun, are called anticrepuscular rays.
In this evening photograph from New Mexico, USA, looking to the opposite horizon from the setting Sun, the shadows, which are in fact parallel, appear to converge at the antisolar point due to perspective. The rising moon can be seen on the right of the picture.
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Anticrepuscular rays appear to converge at a point directly opposite the Sun, called the antisolar point. This picture was taken after sunset from the summit (altitude 1215 m) of Mt. Fichtelberg, in the Ore mountains of Germany. Below the mountain summit and extending to the horizon is an extensive layer of low-level cloud (Stratus or Stratocumulus) formed under an anticyclonic subsidence inversion. In the sky there are Cirrus clouds.
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In a rain shower near sunset, this primary rainbow forms a semicircle centred on the horizon directly opposite the setting Sun. The bow lacks the full colours of the spectrum because when the Sun is near the horizon, the shorter blue and green wavelengths of light are scattered by their long pathway through the atmosphere. The direct light rays forming the rainbow are therefore proportionally higher in the longer, red wavelengths of light.
Converging on the antisolar point (the point directly opposite the Sun) are dark streaks alternating with light beams. These are anticrepuscular rays.
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