Circumhorizontal Arc Over Georgetown, Texas

June 14, 2005

Pict0190 copy

Provided by: Barbara Gettman
Summary authors & editors: Barbara Gettman; Jim Foster

The above photo showing a circumhorizontal arc accenting the spring sky was taken over Georgetown, Texas on April 8, 2005. It was snapped shortly after noon so the Sun was quite high in the sky -- a must to see this type of arc. As with the more prosaic circumzenithal arc, the circumhorizontal arc is formed by similarly oriented ice crystals. For circumhorizontal arcs to form, though, sunlight must enter though an ice crystal's vertical side face and exit through the lower horizontal basal face.

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