katabatic wind

A meteorological term applied to winds which blow downhill due to cold air being pulled by gravity from high ground to low ground. Examples of katabatic winds are found in Greenland and Antarctica.

Etymologically derived from the German katabeinen meaning to descend.

Katabatic flow is a common, daily occurrence worldwide. Solar heating tends to cause upslope flow in valleys during the warm part of the day, unless there is some overriding larger scale weather situation. When the sun gets low at the end of the day and stops heating the valley much of the air that was pushed up and out flows back down the hillsides into the valley. If the valley is well defined and not too wide then the air flowing down the various slopes will converge over the center of the valley, and there will be a broad area of smoothly rising air there. This is known as a Wonder Wind and is highly valued by pilots of soaring aircraft.

There are seasonal winds that flow over and down mountains and so are sometimes described as katabatic, but they are, like the Santa Ana winds of Southern California, the result of large scale conditions (strong high pressure over Utah and the Great Basin in the case of Santa Ana winds) and not diurnal heating/cooling cycles. See foehn.

Formed under special atmospheric conditions, Katabatic Winds are formed when the air flowing over a mountainous area moves downward following the contours of the lee side of the mountain slope, both warming and drying as it descends. This type of air sometimes behaves like an avalanche, gathering speed as it descends. When it reaches the flat land below the mountain, velocity can exceed 100 miles per hour in exposed areas.

In some of its milder forms, this type of descending air and the resulting warm, drying, persistent wind has taken on many localized names.

Area/ Local Name

Western Prairies/ Chinook
Alpine Europe/Foehn
Southern France/Mistral
The Sierrras /The Washoe Zephyr
Southern California/ The Santa Ana

Because Katabatic Winds are warm and dry, they have a huge appetite for moisture and cause it to disappear. Katabatic Winds are rumored to produce physiological effects on humans such as nervousness, instability and a general sense of malaise.