We all know that the air around us has a mass. When moving, that mass of air causes us to experience a force as it flows over us. That force is wind. I don’t suppose I’ve surprised any of you yet? If I have, you probably need to get out more.
Out at sea, wind is created in the normal manner, by air rushing from one area of high pressure to another area of low pressure. Convection of warm and cold air masses causes this movement of air mass. This is what we call ‘wind’.
A katabatic wind is created by the same rush of colder, heavier air but this time the cold air is tumbling off something high, like a mountain range. The heavy, cold air pours off the side of the mountain and hurtles downwards, like an invisible avalanche, rushing towards the plateau below - usually the sea.
Katabatic winds are usually nocturnal phenomena in most parts of the world, especially when there is little cloud, due to lack of heating by the sun. Katabatic wind speeds do not typically exceed 7 - 10 knots. However, where the ground is covered with snow or ice, katabatic winds can occur at any time of day or night with speeds often reaching 20 kts with more if funneling occurs through valleys. Katabatic winds may lead to the formation of frost, mist and fog in valleys.
Other parts of the World where katabatic winds are prevalent are the Arctic and Antarctic, sea areas around high mountainous islands and the Norwegian Fjords and Scottish Lochs.