Spirited Sundog

December 13, 2003


Provided by: Christine Churchill
Summary authors & editors: Christine Churchill

The above photo, showing a brilliant sundog, was taken in November of 2002 from Northern California. This eye-catching patch of light is also called a parahelia. Sun dogs appear 22 degrees from the Sun, or a little more than 2 fists held at arm's length -- they're found at the same altitude as the Sun, to its left and or right. They occur in pairs, but often only one is visible. Their color and brightness varies, however, red is always on the sun-ward side and blue on the outside. Sun dogs are caused when sunlight is refracted through a 22 degree angle by horizontally-oriented, hexagonal ice crystals (in the shape of 6-sided plates), which are typically found in cirrus clouds.

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