Composition and structure of the atmosphere

• The atmosphere is a gaseous layer that surrounds the earth and is made up of nitrogen, oxygen, carbon dioxide, water vapour and other gases
• The atmosphere is important because:

  • it sustains life on earth
  • contains oxygen we need to breathe
  • absorbs harmful UV rays
• Troposphere is the layer of the atmosphere where the temperature is constant. It is the lowest layer of the atmosphere and extends to 12km from the surface
• Stratosphere extends from about 12-50km.
• Ozone occurs in the stratosphere, where it absorbs UV radiation and protects the Earth from harmful UV radiation. It is formed of 3 qxygen atoms