Anticrepuscular rays

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Anticrepuscular rays appear opposite of the setting Sun off the Gulf Coast of the United States, as seen from Florida.
These anticrepuscular rays appear to converge at the antisolar point, as viewed from an aircraft above the clouded ocean.
Anticrepuscular rays appear opposite of a sunrise and perpendicular to a rainbow on the Gulf Coast of Mississippi.

Anticrepuscular rays, or antisolar rays,[1] are atmospheric optical phenomena similar to crepuscular rays, but appear opposite of the Sun in the sky. Anticrepuscular rays are nearly parallel, but appear to converge toward the antisolar point due to linear perspective.[2] Anticrepuscular rays are most frequently visible around sunrise or sunset.

Appearing to radiate from the Sun, crepuscular rays usually look much brighter than anticrepuscular rays. This is because the atmospheric light scattering making the crepuscular rays visible occurs at low angles to the horizon (see Mie theory).

Although anticrepuscular rays appear to converge toward the antisolar point, the convergence is actually an optical illusion. The rays are in fact almost parallel, and their apparent convergence is toward a vanishing point, which is an infinite distance away from the viewer.[3]

References[edit]

  1. ^ Cowley, Les, "Anti-solar (anti-crepuscular) rays", Atmospheric Optics, retrieved March 19, 2015
  2. ^ John A. Day (2005), The Book of Clouds, Sterling Publishing Company, Inc., pp. 124–127, ISBN 978-1-4027-2813-6, retrieved 2010-10-09
  3. ^ Cowley, Les, "Antisolar rays", Atmospheric Optics, retrieved March 19, 2015

External links[edit]