The photo above showing what looks like a scene from a science-fiction film was captured in Abilene, Texas on August 29, 2011. This shaft of blue light penetrating a tear in a stratus cloud deck is simply a crepuscular ray seen from a sideways perspective. Photographer: Steve Templeton; Steve’s Web site
Though “crepuscular” refers to twilight, when such rays are most noticeable, crepuscular rays can occur anytime a cloud or a cloud layer moves in front of the Sun, even in the middle of the day. Because this ray is shadowed by the cloud layer above, it has a bluish hue — only blue skylight is reaching the shadows.