Earth is the only planet in the solar system with an atmosphere that can support life. Its mantle of gases not only contains the air we breathe, but also protects us from the sun’s radiation and heat. As if that were not enough, the atmosphere warms the planet during the day and cools it at night.
In terms of its extension, the atmosphere is approximately 480 kilometers thick, although most of it is located 16 kilometers from the surface. Air pressure decreases with altitude, so there is less oxygen to breathe as you climb a mountain. From a height of 2,500 meters, the lack of oxygen can be noticed, which is why some people get dizzy and feel significant fatigue.
Layers of the atmosphere
The atmosphere is divided into five main layers: exosphere, thermosphere, mesosphere, stratosphere, and troposphere. The atmosphere thins in each upper layer until the gases dissipate into space. Although there is no definite boundary between the atmosphere and space, there is an imaginary line that separates them (the Karman line). This is the point where scientists say the atmosphere meets outer space.
The troposphere is the layer closest to the Earth’s surface. It is between 7 and 20 kilometers thick and contains half of the Earth’s atmosphere. Also, most of the water vapor and dust in the atmosphere is found in this layer, which is why clouds form right in this layer.
The stratosphere is the second layer. Here is ozone that heats the atmosphere and absorbs harmful radiation from the Sun. The air in this layer is very dry, so this is where jet planes fly.
The mesosphere is the third layer of the atmosphere. The upper part of the mesosphere is the coldest part of the atmosphere, with temperatures of minus 90 degrees Celsius . This layer is difficult to study since the weather balloons do not reach the sufficient height. However, meteorites are known to disintegrate right in this layer.
In the thermosphere (fourth layer of the atmosphere) temperatures can reach up to 1,500 degrees Celsius. Although the thermosphere is part of the atmosphere, the density of the air is so low that most of this layer is considered outer space. In fact, in this layer is the International Space Station that orbits the Earth. Also, the exosphere is the highest and thinnest layer. It is also the point where the atmosphere merges with outer space. This layer is made up of highly dispersed hydrogen and helium particles.
