Colorful Cloud

August 11, 2004


Provided and copyright by: Dawn Whalen
Summary authors & editors: Dawn Whalen; Jim Foster

The photo above showing what seems to be an intriguing fragment of a circumhorizontal arc was taken in Wyoming on July 10, 2004. The delicate, almost pastel colors, as well as its position in the sky lends credence to this assessment. A circumhorizontal arc is a halo phenomenon -- formed by oriented ice crystals usually in cirrus type clouds. They're typically only observed during mid-day in the late spring and summer months (in the mid latitudes) when the Sun attains an elevation greater than about 58 degrees above the horizon. See also the Earth Science Picture of the Day for March 25, 2004 and tomorrow's "picture of the day."

If the weather permits tonight and early tomorrow morning, look for "shooting stars" from the annual Perseid Meteor Shower. The Moon is playing fair and briefly departing the night sky so as not to diminish the luster of those meteors falling into our atmosphere. Meteors from the Perseids can occur most anytime in early to mid August, but peak activity is expected tonight.

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