Atmosphere

  • ATMOSPHERE
  • The atmosphere is a mixture of a layer of gases enveloping the earth, held by gravitational force. Almost all the atmosphere (97 per cent) lies within 29 km of the earth’s surface.
  • LAYERS OF ATMOSPHERE
  • Troposphere: Layer nearest to earth’s surface. Thickness varies from 8 km at the poles to 16 km at the equator.
  • All weather phenomenon occur here.
  • Stratosphere: Extend from 16 km to 50 km ht. The temperature ceases to fail with the increase of height in this layer.
  • Stratosphere provides ideal conditions for flying large airplanes.
  • Contains ozone (25-30 km from earth’s surface), region being called Ozonosphere
  • Mesosphere: Upto a height of about 80 km.
  • Lonosphere: Extends to about 500-600 km.
  • Protects earth from harmful radiation. It also protects earth from falling meteorites, as most of them burn out in this region.
  • Exosphere: Here the earth’s gravity is extremely weak.
  • Upper limit quite uncertain.