Thursday, September 17, 2009

Santa Ana Winds

Santa Ana winds are strong, extremely dry offshore winds that characteristically sweep through in Southern California and northern Baja California in late fall into winter. They can range from hot to cold, depending on the prevailing temperatures in the source regions, the Great Basin and upper Mojave Desert. However, the winds are remembered most for the hot dry weather (often the hottest of the year) that they bring in the fall.

According to the Los Angeles Almanac: "The original spelling of the name of the winds is unclear, not to mention the origin. The name "Santa Ana Winds" is said to be traced to Spanish California, when the winds were called devil winds due to their heat. Santa Ana winds may get their name from the Santa Ana Mountains in Orange County, the Santa Ana River or Santa Ana Canyon, along which the winds are particularly strong. The original form may have been Satanás winds, from the Spanish vientos de Satán ("winds of Satan"). Sanatanas is a rarer form of Satanás and is a translation of a native name in an unspecified language."

Although the winds often have a destructive nature, they have some positive benefits as well. They cause cold water to rise from below the surface layer of the ocean, bringing with it many nutrients that ultimately benefit local fisheries. As the winds blow over the ocean, sea surface temperatures drop about 4°C (7°F), indicating the upwelling. Chlorophyll concentrations in the surface water go from negligible, in the absence of winds, to very active at more than 1.5 milligrams per cubic meter in the presence of the winds.

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