Thursday, October 05, 2006
When I went outside this morning, I saw these crepuscular rays converging toward the rising sun. On October 1, t.beth of Firefly Forest posted a beautiful photo of crepuscular rays radiating down from the afternoon sun through a dramatic cloudy sky. This phenomenon isn't uncommon, but it's always beautiful.
I hadn't thought much about them before, but, prompted by t.beth's post, I looked up crepuscular rays on the Atmospheric Optics web site. There one can find more wonderful photos and explanations of both crepuscular rays (apparently converging toward the sun) and anti-crepuscular rays (apparently converging toward the anti-solar point, 180 degrees from the sun). In fact, the rays are parallel shafts of sunlight from holes in the clouds - the seeming convergence caused by a perspective effect. The Atmospheric Optics web site also has a spectacular photo taken with a fisheye lens of rays and shadows stretching across the earth, showing that crepuscular and anti-crepuscular rays are actually the same objects.