Mountain climate

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Mountain climate is a vague generic term for climates that differ from the climate of the surrounding plains (both low and high plains ) due to the height above sea level and the weather-influencing topography of a mountain (especially high mountains ) through a significantly lower air temperature and mostly different precipitation conditions .

The interplay of increasing heat radiation , decreasing air pressure and the corresponding negative temperature gradient in the lowest layer of the atmosphere basically causes temperatures to decrease averaging 0.5 ° C per 100 meters with increasing altitude. Isolated mountain peaks are always cooler than mountain ranges or high plateaus at the same height .

In this respect, the sea level has a significant influence on the annual and diurnal temperature change and thus on the vegetation period of the plants, which can be defined according to different altitude levels . In connection with the amount and distribution of precipitation results in the humidity or aridity of the mountain climate.

Since mountains also have an increasing influence on the atmospheric air currents - and thus on the weather - depending on the altitude , the moisture conditions there are often different than in the flat surrounding areas (see, for example, inclined rain ).

The height of a mountain range and the slope also have an influence on:

Mountains of the evergreen tropics

There are numerous mountain ranges in the earth's evergreen tropics : the Andes, the Venezuelan highlands and the Atlantic mountain range in South America, the mountain ranges of East Africa and the mountains of the Indomalayan region and the Sunda Islands in Asia. Depending on the region, the tropical rainforest changes into the tropical mountain forest between heights of 1000 and 1500 . The trees are a bit lower here and the undergrowth is much stronger. Cloud forests and cloud forests occur at altitudes from around 2000–3500 meters . The climate here is very humid and temperate with typical average temperatures of 8 ° C. The tree line is at around 4,000 meters , above are alpine steppes with average temperatures barely above 0 ° C. The snow line in the humid tropics is around 5000–6000 meters above sea level, depending on the region. Above, the average temperatures are below 0 ° C and there is eternal ice.

Mountains of the tropical savannas

In particular in East Africa, Tanzania, Kenya and Ethiopia there are extensive savannas with mountain ranges. The higher you go, the cooler and wetter it gets. The regions below 1500 meters are tropically hot and too dry for forests. In the subtropical altitude, on the other hand, there are often regions in which the precipitation is high enough for forests. Temperate cloud forests can almost always be found in altitudes of around 3000 meters, giving way to cool steppes in over 4000 meters.

Mountains in tropical and subtropical desert regions

Because the precipitation increases with altitude, mountain ranges in desert regions often offer green landscapes. For example, at higher altitudes in the Sahara over 2000 meters, there is sometimes a green landscape with a moderate climate. In the south of the Arabian Peninsula, in the Atlas Mountains and in Iran, sometimes deciduous deciduous forests with an almost central European climate thrive at these heights.

Mountains in the humid subtropics

In China, Japan, the Canary Islands and southern Brazil, there are low-lying wet forests with a subtropical climate. In the Canary Islands, unique laurel forests thrive in this zone. Since the temperature decreases with increasing altitude, the climate becomes more moderate above about 1000–1500 meters. Here the annual average temperature corresponds roughly to that in Central Europe, but the seasonal fluctuations are lower. Coniferous forests often appear in the temperate zone. Examples of this are the coniferous forests in southern Brazil, the coniferous forests on the Canary Islands and in central China. While in Brazil and the Canary Islands primarily high mountain steppes occur above the temperate zone, cool mountain conifer forests grow in Asia, in which it snows a lot in winter and the average temperature is barely above 0 ° C. Above this zone, alpine grasslands extend, which, depending on the region, can be very dry, but also very humid. The snow line is similar to that in the tropics and in the subtropics at around 5000–6000 meters.

Mountains in the temperate zone

At around 1000 meters above sea level, in the temperate zone, deciduous deciduous forests, steppe landscapes and temperate moist forests give way to cool mountain conifer forests. These occur z. B. in the Rocky Mountains, the Alps, the Caucasus or the Altai Mountains. Mountain conifer forests in this zone usually receive a lot of snow in winter and are mild in summer. Depending on the region, the alpine mat level follows between 2000 and 3000 meters. There are no trees growing here and the snowmelt usually doesn't start until May. In the temperate zone, the climatic snow line is around 4000 meters.

Mountains in the boreal zone

Mountains in the boreal zone exist in Scandinavia. Other examples are the Urals, the East Siberian Mountains, Tierra del Fuego, southern Alaska and the northern Rocky Mountains. Depending on the region, conifers and birch trees grow in depths below 1000 meters. The tree line is usually very low at a few hundred meters. In summer, the vast grasslands of the tundra extend over it. The limit of glaciation in the boreal zone is 2000 to 3000 meters. A special feature of this zone is that inversion weather patterns often occur in winter , which is why the average temperature of the winter months is often not colder, but warmer than that in the valleys.

Mountains in the polar zone

There are no trees in the polar regions , the vegetation below 1000 meters consists of polar tundra . Glaciers stretch just a few hundred meters above sea level. Examples are Greenland, the northern Canadian islands, northern Alaska, northern Siberia, Svalbard and the Antarctic Peninsula. In summer, the average temperature decreases with altitude. In winter, when the sea is icy, inversions often occur, so that it is warmer on the mountains than in the valleys.

Mountains in the eternal ice

In northern Greenland and Antarctica, mountain ranges lie in landscapes that are icy even at sea level in summer. Due to inversion weather conditions, the average temperature hardly changes with altitude, both in winter and in summer. Inland it is generally much colder than near the sea. A specialty in the Antarctic mountains are dry valleys , which due to the mountain ranges receive no precipitation at all. They are often even drier than the Sahara. There is no snow at all here, although the temperature almost never rises above −10 ° C even in summer.

Individual evidence

  1. ↑ Dieter Heinrich, Manfred Hergt: Atlas for ecology. Deutscher Taschenbuch Verlag, Munich 1990, ISBN 3-423-03228-6 . P. 95.