The Santa Ana winds, also sometimes called the devil winds, are strong, extremely dry downslope winds that originate inland and affect coastal Southern California and northern Baja California. They originate from cool, dry high-pressure air masses in the Great Basin.
The Santa Ana winds sweep down from the deserts and across coastal Southern California, pushing dust and smoke from wildfires far out over the Pacific Ocean. Los Angeles is in the upper left of this image, while San Diego is near the center.
QuikSCAT image showing the speed of the Santa Ana winds (m/s)
The Thomas Fire and two other fires burn out of control near Ventura in December 2017, with a strong Santa Ana wind driving the flames toward the coast and blowing the smoke offshore.
Hygrometer showing low humidity during a Santa Ana wind event
A katabatic wind carries high-density air from a higher elevation down a slope under the force of gravity. Such winds are sometimes also called fall winds; the spelling catabatic winds
is also used. Katabatic winds can rush down elevated slopes at hurricane speeds, but most are not that intense and many are 10 knots or less.
Plateau-cooled air falls into the Makhtesh Ramon, traced by radiation fog, just after dawn. Radiative cooling of the desert highlands chills the air, making it more dense than the air over the lowlands. Cooler air can also hold less water vapour; it condenses out as tiny fog droplets, which re-evaporate as the air warms. Here, the falling air is warming adiabatically, and so the fog re-evaporates as it falls.
Katabatic wind in Antarctica
