Why are mountains covered with snow

How the mountains affect the weather and climate

As still and motionless as a mountain may appear, it shows itself in a new shape every day. Today the peaks are enveloped by thick clouds, tomorrow its magnificent shape can be clearly seen from afar. Because the mountains have a decisive influence on the regional weather and climate.


Rainmaker

A potential rain cloud is usually a deep cloud with a high water content. In order for it to rain down, it needs a little push. This is where the mountains come into play. If a cloud drifts towards a mountain, it is forced to rise. This lifts the cloud into higher, colder layers of air. In the cold mountain air, the water vapor condenses and combines to form small water droplets, which finally fall to the ground as rain (if it is cold enough, as snow). That is why it rains more often and heavily in the mountains than in the plains.

The clouds drift up along the mountain and rain falls. jplenio, pixabay

Moated castle

As natural “water towers”, the mountains store most of the precious water in frozen form. The glaciers and snow fields melt slowly over months or even years and feed the rivers in the lowlands. This is how green, fertile valleys are created. The more than 200,000 glaciers, snowfields, alpine lakes and wetlands in the mountains around the world provide around half of the total fresh water that we humans consume.

Mountains are one of the most important sources of drinking water on our planet. Adam Derewecki, pixabay

Climate divide

Mountains often also act as a climate divide. Due to their extent and height, such mountains separate two climatically different regions. The horizontal air exchange is prevented by the mountain ridge and solar radiation is reduced. Therefore, the two sides of the mountain show different conditions in terms of temperature, air pressure, humidity and precipitation.

In geography, the mountain sides are differentiated in relation to the wind. The Windward side is the side of the mountain that faces the main regional wind direction. The opposite is the case Lee side turned away from the wind. On the windward side, the air masses from the mountain are forced to rise, so that rain often falls on this side. There is often a cool, humid climate there. The dry air mass now moves over the mountain to the leeward side, warms up as it descends and leads to a warm, dry climate there. A vivid example are the Andes, which separate the dry west coast of South America from the wet east.

The Atacama Desert, the driest desert on earth, extends on the lee side of the Andes. Luis Valiente, pixabay

Global influence

Mountains not only have a local but also a global influence on the climate. Because not only the poles, but also the snow-capped peaks and glacier areas of the mountains contribute significantly to the reflectivity - the albedo effect - of the earth. Without this effect, the earth would absorb most of the sun's rays and become very hot.

The snow-capped peaks of the Schilthorn reflect the rays of the beautiful sunset. Julius Silver, pixabay

So the mountains essentially shape the weather and the climate. Of course, the reverse is also true. In the next post in our series of articles, we'll look at how changing weather and climate affect the mountains.

Sources and further information:
Why there is more precipitation in the mountains
National Geographic: Glaciers are melting all over the world
Lexicon of Geography: Albedo
Lexicon of Geography: Windward and Lee