Difference in Weather Between Two Sides of a Mountain

Incredible footage shows the same mountain, with two weather systems. But why is the difference?

The amazing phenomenon shown in the below video is due to the fact that much of airborne moisture falls as rain on the windward side of mountains (the side of a mountain that is facing the direction the wind is coming from).

At the same time, the Leeward side (the wind protected side of a mountain) gets far less rain. This effect is called a “rain shadow”, and it often produces a desert.

So why are leeward sides of mountains drier than windward? By the time the air gets to the leeward side of the mountain it has already lost a good part of its moisture, making that side much more arid.

Many of the deserts of the world are formed this way – because of the lack of moisture blocked by the mountains. The Gobi desert, for example, is situated behind the Himalaya mountain range in Asia. One of the largest deserts on Earth on the leeward side of the world’s largest mountain. No coincidence.

This amazing video by climber Arete Freshfield illustrates the above phenomenon. It was taken at the Tour Ronde on the Mont Blanc massif.

Credit: Arete Freshfield

Sources: 1, 2


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