Wednesday, October 24, 2007

Santa Ana Winds

Those hot dry winds that come down through the mountain passes and curl your hair and make your nerves jump and your skin itch. On nights like that every booze party ends in a fight. Meek little wives feel the edge of the carving knife and study their husbands' necks. Anything can happen.

-Raymond Chandler, "Red Wind"

Those hot, dry Santa Ana winds are back this week, up to no good as usual.

The Santa Anas are similar to the föhn winds of the Alps: high pressure inland sends air speeding over the mountains, where the winds cool down and lose their capacity to hold moisture. Then, forced downhill again towards the coast, the winds gain heat adiabatically in increasing atmospheric pressure. At the same time, the winds gain speed as they funnel through narrow mountain passes. The hot, dry, moving air creates perfect conditions for wildland fires, which is why southern California is burning.

In some areas, the winds are blowing at hurricane speeds, sending smoke and dust hundreds of miles out over the Pacific Ocean...

Image: NASA's Looking at Earth site (thanks for the tip, widgery!)

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