Where is the tropopause located

Mountain weather lexicon

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the atmosphere

Troposphere - stratosphere

Our atmosphere in which we humans live is wrapped around the entire globe like a thin shell and consists of different gases. From the ground, the cloudless sky looks like an infinitely wide blue sea. In reality, however, the atmosphere is only very thin compared to the globe. Because of its great mass, our planet pulls everything closer to itself, the closer the distance to the other mass, the stronger it is. Even the lightest objects such as the air particles (molecules) that surround us are increasingly attracted towards the bottom. Following this gravity, there are a lot of air particles directly above the earth's surface. The further we look up, the less air there is. You could also say that the air becomes “thinner” further up. So it happens that about 70% of the total air mass in our atmosphere is in the lowest 10 km in the Central European annual average. Since every air particle also has a minimal weight, it exerts pressure on the particle below it. If you stack a lot of air particles on top of each other, the pressure on the bottom particle increases more and more. This means that the air pressure on the ground is highest and continues to decrease with increasing altitude. So air has certain similarities to water. If you dive down in the swimming pool or in the sea, you can feel the pressure increase very quickly. So we humans live, so to speak, at the bottom of an ocean of air that rotates with the earth on its own axis. The above-mentioned, with us on average the lowest 10 km of the earth's atmosphere, also called the troposphere (see picture below), represent the layer in which the vast majority of the weather on our planet takes place. High and low pressure areas form here, which in turn drive warm and cold fronts and ensure precipitation, storms or sunshine. This layer is bounded at the top by the tropopause in the transition to the stratosphere.

If you hike up from the ground, the temperatures will normally drop further and further. At an altitude of around 10 to 50 km above the ground, however, the temperatures temporarily rise again and reach just below 0 degrees at the top before it quickly and significantly colder again in the high atmosphere. This warmer layer is known as the stratosphere. The rise in temperature in this layer is due to the ozone particles located there. These arise from oxygen and the invisible ultraviolet solar radiation (UV), the short-wave portion of bundles of rays. In doing so, ozone absorbs part of the radiation and releases the energy to its surroundings, which leads to the aforementioned warming. The low proportion of air particles in this layer means that hardly any weather-related processes take place. The stratosphere appears drier and emptier of air particles towards the top. Only in the lowest layer of the stratosphere can high-reaching thunderclouds get lost from time to time.
Ozone layer
Incidentally, the greatest ozone concentration is in the lower stratosphere, as this is where most of the oxygen particles are available for production. It is also called the ozone layer, to which we owe that one does not get sunburn all the time on earth. The ultraviolet rays (commonly known as UV light) absorbed by the ozone are very harmful to human skin. The more ozone particles there are up there, the more the living beings, including plants, are protected from dangerous ultraviolet radiation.
Too many ozone particles bring disadvantages for people and the climate not only down here but also up here!
You can find more information about ozone, the ozone hole and the ozone layer in our mountain weather lexicon under ozone
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This is where the significant weather activity ends ...

Above, under the atmosphere, we have explained some properties of the two lowest layers of air on our planet, the troposphere and the stratosphere. Now we want to go into more detail on the large-scale and seasonally varying border areas of these two atmospheric layers. We are talking about the so-called tropopause. If you move from the ground up in the atmosphere, the temperature ultimately decreases further and further. At a certain point, however, this drop in temperature stagnates and a little further up it even becomes warmer again in the stratosphere, so it is a so-called temperature inversion (see picture above). The tropopause is where the temperature previously reached its minimum. It represents the transition from the weather-active tropopause to the increasingly dry stratosphere. In fact, ascending air parcels can only continue to rise as long as they are warmer than the air masses in their vicinity. That is why in the tropopause with maximally thin feather clouds (high ice clouds) or in thunderstorms at the latest in the lowest area of ​​the stratosphere, the weather is over. Even thunderstorm clouds that shoot up into the air do not get any further due to the rise in temperature (stable, constant inversion) and then quickly appear as ice clouds through the "cover". In the case of particularly strong inflowing air masses (updrafts), they only spread slightly higher and are forced to spread horizontally. So they put a wide ice screen (anvil) on top of the thunderstorm, reminiscent of a mushroom, which can reach as far as the lower stratosphere. The tropopause, as the border area of ​​the weather-active zone, is not always and certainly not over a large area at the same height everywhere. It expands with light warm air and contracts with heavy cold air (see picture below). Therefore, the tropopause is generally higher in summer than in winter and increases enormously from the poles to the equator.

The height of the tropopause is therefore very variable and depends largely on the temperature below this layer. The air molecules move very quickly in warm summer air, they literally swirl through our atmosphere. Because of these many movements, the air particles also require a lot of space. As a result, the lowest layer of the atmosphere is arched and reaches up to about 12 km in altitude, at the equator also up to 16 or 18 km in height. Then it is separated from the second layer, the stratosphere, by the tropopause. On cold winter days, however, the movement of the molecules is very sluggish and slow. As a result, they can press close together, which means that the troposphere is significantly narrower and the tropopause is therefore much lower. In winter it is often only 5 to 7 km.
Of course, this also means that the weather in winter takes place in a significantly thinner layer than in summer. We therefore only know high-reaching shower and thunderclouds from the warm summer time. In winter, on the other hand, flat layer clouds dominate, but these can no less ensure precipitation, because for a proper snowfall often only a 4 to 5 km thick layer of air is sufficient.