This is a photograph of cirrostratus clouds near Moab, Utah.
Click on image for full size
Courtesy of Anne Pharamond

Cirrostratus

Cirrostratus (weather symbol - Cs) clouds consist almost entirely of ice crystals and belong to the High Cloud (5000-13000m) group. They are sheetlike thin clouds that usually cover the entire sky.

The sun or moon can shine through cirrostratus clouds . Sometimes, the sun or moon will appear to have a halo around it when in the presence of cirrostratus. The ice crystals from the cloud refracts the light from the sun or moon, creating a halo. This halo is the width of your hand when you hold it out at arm's length.

Cirrostratus clouds usually come 12-24 hours before a rain or snow storm. This is especially true if Middle group clouds are associated with it. You can distinguish a cirrostratus from an altostratus cloud by looking for your shadow on the ground. If you can see your shadow, then the cloud is cirrostratus.


Last modified September 25, 2007 by Becca Hatheway.

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