Southern California's "Santa Anas" are dry, north-easterly winds
having speeds in excess of 25 knots (46 kilometers/hour). Santa Ana
conditions are commonly associated with gusts of more than twice
this level. These offshore winds usually occur in late fall and
winter when a high pressure system forms in the Great Basin between
the Sierra Nevadas and the Rocky Mountains. The air warms as it flows
downslope from the high plateau, and its speed increases dramatically
when forced through narrow canyons and mountain passes. Due to
Southern California's uneven terrain, the strength of the winds varies
greatly from place to place, and the Santa Anas can be sufficiently
strong to pick up surface dust.
This view from the Multi-angle Imaging SpectroRadiometer shows
the pattern of airborne dust stirred up by Santa Ana winds on
February 9, 2002. The image is from MISR's 70-degree forward-viewing
camera, and airborne particulates are especially visible due to
the camera's oblique viewing angle. Southeast of the Los Angeles
Basin, a swirl of dust, probably blown through the Banning Pass,
curves toward the ocean near Dana Point. The largest dust cloud
occurs near Ensenada, in Baja California, Mexico. Also visible in
this image is a blue-gray smoke plume from a small fire located near
the southern flank of Palomar Mountain in Southern California.
This image was acquired during Terra orbit 11423, and represents an
area of about 410 kilometers x 511 kilometers.
MISR was built and is managed by NASA's Jet Propulsion Laboratory,
Pasadena, CA, for NASA's Office of Earth Science, Washington, DC.
The Terra satellite is managed by NASA's Goddard Space Flight Center,
Greenbelt, MD. JPL is a division of the California Institute of
Technology.
Image credit: NASA/GSFC/LaRC/JPL, MISR Team.
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