Visible light, infrared and ultraviolet radiation which the Sun emits is indispensable for life on Earth. However, a part of this radiation can also be very harmful. This applies to the Sun’s ultraviolet rays which Earth’s atmosphere for the most part filters out very efficiently.

Nitrogen, oxygen and ozone molecules in the upper atmosphere and stratosphere absorb ultraviolet light from the Sun, providing a shield that prevents this radiation from passing to the Earth’s surface.

 

Image credits: NASA, ESA

 

Earth’s atmosphere is a mixture of gases {nitrogen (78%), oxygen (21%), other gases (1%)} that becomes thinner until it gradually reaches space.

The Earth’s atmosphere is divided into four layers or ‘spheres’. Each layer is characterized by a different gradient of the temperature as a function of altitude.

• Troposphere
• Stratoshere
• Mesosphere
• Thermosphere and exosphere