Wednesday, September 18, 2013

Crepuscular rays

As I arrived home from work on Monday, I noticed that there were some very nice crepuscular rays in the western sky. These rays, streaming through gaps in the cloud, are columns of sunlit air separated by darker cloud-shadowed regions. While these rays of sunlight appear to radiate outward from the specific point in the sky (where the sun is located), they are actually near-parallel shafts of sunlight, and their apparent convergence is a perspective effect. This is similar to the way that parallel lines will appear to converge at a point far in the distance.  These beautiful rays are commonly seen in the desert skies as a result of our dry atmosphere.  When humidity is high, the light is diffused in the atmosphere making these rays much more difficult to detect.

Click to enlarge

The picture was taken with my Canon T2i and a 24-105mm lens operating at 40mm f/10 with a polarizing filter.  The exposure was 1/200 of a second at ISO 100.