Correction Appended: October 25, 2007
The Santa Ana winds begin cold, gathering power and mass in the high desert between Las Vegas and Los Angeles. Air pressure pushes the winds up and over the San Gabriel Mountains, westward toward the Pacific Ocean, until gravity takes hold. The air becomes compressed as it drops, growing hotter and dryer, stripping moisture from the ground, accelerating sometimes past 100 m.p.h. (160 km/h) as it squeezes through Southern California's many canyons.
The punishing gusts of the Santa Anas herald cursed weather, days and nights of...