Fascinating Meteorology Terms: Katabatic Wind

(Diagram of Katabatic wind direction from a mountain plateau. Photo from Meteorology Today By C. Ahrens.)

Katabatic wind is a dense cold wind that sinks down from high mountain plateaus to valleys below. It is described by Meteorologists as heavy cold air that practically mimics the movement of mountain water as it flows downslope and waterfalls over steep canyons. Depending on the temperature of the air it displaces during its descent, katabatic wind can become violent, reaching speeds up to 100 mph.
Up on a high plateau of a mountain range, snow tends to be prominent during the winter months and into the spring. This snowpack keeps the air above it cold and dry. Air in the valley tends to be much warmer than the air on the plateau. To understand what makes this air start to move downslope, it is important to know the laws of temperature and pressure. Cold dense air is associated with higher pressure and warmer, less dense air is associated with lower pressure. Air tends to rise when it is warm and sink when it’s cool. Areas of higher pressure will move toward areas of lower pressure to try and replace the air that is lifted. The difference between areas of high pressure and low pressure is called a pressure gradient. The quicker the pressure changes, the stronger the pressure gradient. Therefore, the faster the air from the area of high pressure will move towards the area of low pressure.
The cold, dry air above the surface of the mountain plateau forms a small area of high pressure. As the air in the valley gets warmer, it starts to rise. This causes that high pressure over the snow to move toward that warmer, lifting air. This cold, dense air will eventually move off the plateau. With gravity taking hold, it will start falling downslope, picking up speed as it falls into warmer and warmer air. There is nothing to hold it back as it slips down slopes and plummets over cliffs. Reaching speeds up to 100 mph, this cold air becomes a violent wind that can topple trees and damage crops. Although it can reach such speeds, katabatic wind isn’t always as violent of a wind. It can rage anywhere between 10 mph to 100 mph depending the pressure gradient from the top of the plateau to the bottom of the valley. The stronger the pressure gradient the quicker the air will sink and pick up speed.
Katabatic wind is observed in many parts of the world with high mountain ranges and plateaus. You are most likely to experience katabatic wind in places northeast of the Adriatic sea that reside at the base of the Carpathian mountains, the Rhone Valley that sits at the base of the western mountain range in France, in Columbia at the base of the Cascade mountains, at Yosemite National Park in California and in places like Greenland and Antarctica. All these places where katabatic wind is observed, have other interesting names for the phenomenon. Areas south of the Carpathian mountains call it “Bora wind”, in France they call it “Mistral wind” and in Columbia they call it “Columbia Gorge wind”. Some areas see katabatic wind much stronger than others depending on the climate of the valley versus the elevational climates of the plateau it sits at the foot of.
Although it may become a violent wind, in most cases some natives of areas that see katabatic wind describe their experience as a cold wind sweeping through that forces them to put on a jacket. In another instance, trees toppled over at a campground in Yosemite National Park injuring a park employee that was sleeping in a tent. Wind can be both enjoyable and dangerous depending on the circumstances. It is certainly interesting to learn that there are many different types of wind that have fascinating terminology associated with them.   

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© 2019 Meteorologist Alexandria Maynard