Anticrepuscular rays

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Anticrepuscular rays toward the eastern horizon, as seen from Colorado at dusk
These anticrepuscular rays appear to converge at the antisolar point, as seen from an aircraft above the clouded ocean.
Panoramic image showing both crepuscular and antisolar rays

Anticrepuscular rays, or antisolar rays,

linear perspective.[2][3]

Anticrepuscular rays are most frequently visible around sunrise or sunset. This is because the atmospheric light scattering that makes them visible (backscattering) is larger for low angles to the horizon than most other angles. Anticrepuscular rays are dimmer than crepuscular rays because backscattering is less than forward scattering.

Anticrepuscular rays can be continuous with crepuscular rays, curving across the whole sky in great circles.[4]

Mountain shadow

A common example of a single anticrepuscular ray is provided by the shadow of a mountain at sunset, when viewed from the summit. It appears to be triangular, whatever the shape of the mountain, with the apex at the antisolar point.[4]

Wagon-wheel spokes

A "wagon-wheel spokes" double rainbow with anti-crepuscular rays, Hurunui, New Zealand

Anticrepuscular rays are sometimes seen enclosed by a rainbow. In this case they can be called wagon-wheel spokes.[4]

See also

References

  1. ^ Cowley, Les, "Anti-solar (anti-crepuscular) rays", Atmospheric Optics, retrieved March 19, 2015
  2. ISBN 978-1-4027-2813-6
  3. ^ Cowley, Les, "Antisolar rays", Atmospheric Optics, retrieved March 19, 2015
  4. ^ a b c Lynch, D. K., & Livingston, W. (1995). Color and light in nature. Cambridge: Cambridge University Press.

External links

Media related to Anticrepuscular rays at Wikimedia Commons


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