"The Devil's Wind"

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  • Downtown Los Angeles. Hundreds of thousands of homes lost power around southern California as Santa Ana winds felled power lines and trees. Photo: Yui Mok/PA.

    Sunrise over the Mojave Desert. Photo: Chris Ison/PA Wire

    Mammoth Mountain down San Joaquin Valley. Photo: David Richardson, Duke University.

  • "The Devil's Wind"
    02.12.2011 09:39

     

    A fearsome wind blowing across southern California has toppled trees and power lines, leaving about 300,000 homes with no electricity on Thursday.

    This is the Santa Ana, a wind that can brew up throughout the year but which tends to be strongest during late autumn and early winter, and this one is being described as one of the most powerful in decades.

    It is producing gusts of 60mph in coastal and valley locations, and in excess of 80 mph through canyons and mountain passes. At WhitakerPeak in Los AngelesCounty a gust of 97mph was reported on Wednesday night, and high up in the Mammoth Mountain Ski Area an automatic weather station recorded a gust of 150 mph.

    High pressure has built strongly over the northeast Pacific and the north-western US, with low pressure near the northern Gulf of California, producing strengthening east to north-easterly winds in between.

    But that is not the whole story. Cool air descends from the Mojave Desert in a rush, getting channelled and squeezed through valleys and canyons, accelerating the wind sometimes close to hurricane force – the Bernoulli effect.

    The Santa Ana can be a hot wind because of compression of air as it descends towards the Pacific coast. The high temperatures and strong arid winds can fuel huge and deadly wildfires, such as one in October 2003 that burned over 290,000 hectares of the chaparral. A red flag warning of high fire danger was raised on Wednesday night.

    The name may be derived from one of several locations names Santa Ana in southern California. But a tempting explanation is that it may be an Anglicised  corruption of a Spanish phrase. The heat and fire with which it can be associated inspired Spanish speakers to call it Vientos de Satan, meaning “Winds of Satan”.

    By: Stephen Davenport