Sometimes known as the "devil winds" across Southern California, Santa Ana winds are notorious for the part they play in fanning fires and causing them to spread. They are warm and dry, reaching speeds that can exceed 40mph.
Wind blows down across and over the mountains between coastal California and the Mojave Desert - as it comes down, adiabatic heating causes the wind to be compressed and its temperature warms up. As this air becomes hotter, the relative humidity drops down, with record levels coming in as low as 10% or 20%. This incredibly low humidity level blowing over the land contributes to the drying out of vegetation, effectively making it defenseless tinder for wildfires. As these winds pass through canyons and dips and valleys, they fan flames, speeding up as they move through land that is consisted of varying heights. The frictions caused as it passes through obstacles like canyons creates swirling winds, called eddies. This irregularity can result in periods of still winds followed by periods of swift, fierce gusts. These Santa Ana winds can change direction quickly and without warning, causing flames to spread and grow bigger at a rate that is hard to follow and anticipate. In return, these fires feed the winds. Fire causes the air to grow warm, making it rise - as a result, more gusts are formed, travelling in various directions.
SANTA ANA
WINDS
Their unprecendented effect on the severity and spread of wildfires in the US.
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