Southern California’s “Santa Anas” are dry, north-easterly winds havingspeeds in excess of 25 knots (46 kilometers/hour). Santa Ana conditionsare commonly associated with gusts of more than twice this level. Theseoffshore winds usually occur in late fall and winter when a highpressure system forms in the Great Basin between the Sierra Nevadas andthe Rocky Mountains. The air warms as it flows downslope from the highplateau, and its speed increases dramatically when forced through narrowcanyons and mountain passes. Due to Southern California’s uneventerrain, 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 thepattern of airborne dust stirred up by Santa Ana winds on February 9,2002. The image is from MISR’s 70-degree forward-viewing camera, andairborne particulates are especially visible due to the camera’s obliqueviewing angle. Southeast of the Los Angeles Basin, a swirl of dust,probably blown through the Banning Pass, curves toward the ocean nearDana Point. The largest dust cloud occurs near Ensenada, in BajaCalifornia, Mexico. Also visible in this image is a blue-gray smokeplume from a small fire located near the southern flank of PalomarMountain in Southern California.
This image represents an area of about 410 kilometers x 511 kilometers.
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Image courtesy NASA/GSFC/LaRC/JPL, MISR Team.
