Atmosphere of the Earth
Atmosphere and climate change
978-3-14-100890-6 | Page 20 | Ill. 1
Overview
The Earth's atmosphere can be divided into layers according to the temperature behaviour. Temperatures drop from the Earth's surface to around -60°C at an altitude of around 15 kilometres. This is the area in which all of the Earth's weather takes place. It is called the troposphere. The boundary to the stratosphere above is the tropopause.
Upper layers of the Earth's atmosphere
The transition between the troposphere and the stratosphere is marked by a temperature inversion. Temperatures rise again up to an altitude of around 50 kilometres. They finally reach the freezing point in the stratopause region. The reason for this temperature rise is the absorption of energy-rich UV radiation in the ozone layer. In the stratopause, the air pressure is only about one thousandth of the air pressure at the Earth's surface. In the mesosphere above, temperatures decrease again. At the upper limit of this layer, at an altitude of about 85 kilometres, they are -75°C. The air pressure there at the mesopause is only one hundred thousandth of the value near the ground, and the density is extremely low. In the thermosphere above, the ionisation of the air by electromagnetic particles of the solar wind causes light phenomena in the form of northern lights. Above an altitude of about 500 kilometres, the exosphere begins. It marks the transition from the atmosphere into space.
