Rainbow Spokes Over Namib Desert

July 08, 2008

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Provided and Copyright by: Alex Langoussis
Summary Author and Editor: Alex Langoussis, Jim Foster

In the Namib Desert of western Africa, 2006 was one of the rainiest years on record, providing the opportunity to enjoy numerous rainbows during my two month stay. This one was my favorite favorites! It's referred to as a "rainbow wheel" and results when anticrepuscular rays are visible at the same time a rainbow forms. Rainbows are visible only at the anti-solar point directly opposite of the Sun. Anticrepuscular rays come into view on the opposite side of the horizon from the setting Sun. Only on rare, fortuitous occasions do the two gloriously coincide. The "spokes" are actually beams of sunlight filtering through gaps in clouds on the Sun-side of the sky. Because of perspective, these beams appear to converge toward the horizon -- like railroad tracks that seem to come together in the distance. Photo taken in April of 2006.