Anticrepuscular rays
Anticrepuscular rays are similar to crepuscular rays, but seen opposite the sun in the sky. Anticrepuscular rays are near-parallel, but appear to converge at the antisolar point because of linear perspective.[1] Anticrepuscular rays are most frequently visible near sunrise or sunset. Crepuscular rays are usually much brighter than anticrepuscular rays. This is because for crepuscular rays, seen on the same side of the sky as the sun, the atmospheric light scattering and making them visible is taking place at small angles (see Mie theory).
Although anticrepuscular rays appear to converge onto a point opposite the sun, the convergence is actually an illusion. The rays are in fact (almost) parallel, and the apparent convergence is to the vanishing point at infinity.[2]
[edit] References
- ^ John A. Day (2005), The Book of Clouds, Sterling Publishing Company, Inc., pp. 124–127, ISBN 9781402728136, http://books.google.com/books?id=0cpQGHqxQBUC&pg=PA124&dq=crepuscular+rays+book#v=onepage&q=crepuscular%20rays%20book&f=false, retrieved 2010-10-09.
- ^ Cowley, Les, "Anti-crepuscular rays", Atmospheric Optics, http://www.atoptics.co.uk/atoptics/anti1.htm, retrieved November 1, 2011.
[edit] External links
Media related to Anticrepuscular rays at Wikimedia Commons
- Atmospheric optics: anticrepuscular rays
- Images of anticrepuscular rays at Astronomy Picture of the Day site (copyrighted images):
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