Cirrus Plume over the Sierra Nevadas
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The plume captured in this image from the Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA’s Terra satellite on October 30, 2002, was instigated by air flow over a handful of high peaks in southern California’s Sierra Nevada Mountains. For the air flowing in from the west, the mountains act like a ramp into higher and colder layers of the atmosphere, where water vapor solidifies into tiny ice crystals. The number and size of the ice particles depends on the air temperature, relative humidity, and the vertical speed of the rising air.

The length of this plume is rather unusual. Although topography can force air to rise quickly, gravity will also work quickly to draw the temporarily buoyant air back toward the Earth's surface (if the atmosphere is otherwise stable). As the air descends “downstream” of the mountains, it is generally warming and expanding, processes that favor cloud evaporation, not formation.


You can also download a 250 m resolution KMZ file for use with Google Earth.

  • Jiang, Q., and Doyle, J.D. (2005) Topographically Generated Cloud Plumes. Monthly Weather Review, 134, 2108-2127.


Cirrus Plume over the Sierra Nevadas

September 30, 2006
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