Crepuscular rays!

Unlike some other atmospheric phenomena, crepuscular rays (photo above by Michael Alumbaugh) are fairly easy to observe, and a truly wonderful sight.

Although crepuscular rays appear to radiate out from a single point, this is a perspective effect. They are actually almost parallel, resulting from clouds casting long morning shadows or evening shadows. This becomes clear when crepuscular rays are seen from above, as in this International Space Station photo:

See here for a detailed explanation of the phenomenon. The name comes from the Latin crepusculum (twilight, dusk).

Advertisements