Cirrus Fall Streaks
result from falling ice crystals

Photograph by: Holle

Fall streaks form when snowflakes and ice crystals fall from cirrus clouds. The change in wind with height and how quickly these ice crystals fall determine the shapes and sizes the fall streaks attain. Since ice crystals fall much more slowly than raindrops, fall streaks tend to be stretched out horizontally as well as vertically. Cirrus streaks may be nearly straight, shaped like a comma, or seemingly all tangled together.

Similar to fall streaks is virga, which appears as streamers suspended in the air beneath the base of precipitating clouds. Virga develops when precipitation falls through a layer of dry air and evaporates before reaching the ground.

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Credits and Acknowledgments for WW2010.
Department of Atmospheric Sciences (DAS) at
the University of Illinois at Urbana-Champaign.