Q: What are the layers of Earth's atmosphere?

The Earth's atmosphere consists of 4 main layers, which are:

1. Troposphere: It is the lowest layer of the atmosphere, and it is characterized by the following:

• It extends from the Earth's surface to an average height of 18 km at the equator, and to a height of 9 km at the poles.
• The temperature in this layer decreases with altitude by 6.5 degrees Celsius per kilometer.
• In the lower troposphere, the temperature decreases horizontally from the equator to the poles.
• There is a horizontal and vertical movement of the wind.
• It contains most of the water vapor in the atmosphere in all its forms.
• The layer is characterized by instability, in which convective currents, turbulence, and most weather phenomena, aviation, precipitation, clouds ... etc. occur.
• This layer contains between 80-85% of the mass of the atmosphere.
• The end of the troposphere is called the tropopause.

2. The stratosphere: It is the second layer of the atmosphere, and it is characterized by the following:

• It extends from the tropopause to a height ranging between 50-55 km from the earth's surface.
• The temperature increases with altitude.
• It is completely stable and free from vertical air currents, and free from weather phenomena.
• Water vapor is absent.
• Ozone gas is dispersed.
• The end of the layer is an imaginary surface called the stratopause.

3. The Mesosphere: The third layer of the atmosphere, and is characterized by the following:

• It extends from the stratopause to a height of 80 km from the earth's surface.
• The temperature decreases with altitude.
• There are some air vortices.
• Water vapor is absent.
• It does not have weather phenomena.
• The end of the layer is an imaginary surface called the mesopause.

4. Thermosphere: The fourth layer of the atmosphere and is characterized by the following:

• It extends from the mesopotamia to the end of the atmosphere.
• The temperature increases with altitude due to the absorption of ultraviolet rays by atomic oxygen.
• Diffusion of ions, especially ions of oxygen and nitrogen.