Layers of Atmosphere

  • The atmosphere is composed of gases, water vapour and dust particles
  • Mixer of dust particle and water vapor are called aerosol
  • It receives Incoming solar energy from the sun giving rise to climate.
  • We actually live at the bottom of this indefinite layer of atmosphere
  • One estimate puts this limit at about 600 miles (950 km) above sea level.
  • 99% of the total mass of the atmosphere is confined to the height of 32 km from the earth’s surface.
  Composition of Atmosphere

Composition of Atmosphere

  • The proportion of Gases changes in the higher layers of the atmosphere
  • Oxygen will be almost in negligible quantity at the height of 120 km.
  • Similarly, carbon dioxide and water vapour are found only up to 90 km from the surface of the earth.
 
 

Water Vapour

  • It constituting 2% to 4% of the total volume
  • 90% of moisture content in the atmosphere exists within 6 km of the surface of the earth.
  • Water vapour plays a significant role in the insulating action, of the atmosphere.
  • It absorbs long-wave terrestrial radiation and part of the incoming solar radiation.
  • Water vapour is the source of precipitation and clouds.
 
 

Dust Particles

  • It consist of sand particles, pollen grains, small organisms, soot, ocean salts
  • These solid particles perform the function of absorbing, reflecting and scattering the radiation.
  • It responsible for the orange and red colors at sunset and sunrise
  • Blue color of the sky is due to selective scattering by dust particles.
  • The Dust particles are an important factor in the formation of clouds, fog and hailstones.
 
 

Structure of Atmosphere

  • The atmosphere consists of different layers with varying density and temperature.
  • Density is highest near the surface of the earth and decreases with increasing altitude.
  • The column of atmosphere is divided into 5 different layers depending upon the temperature condition.
 
Layers of Atmosphere

Troposphere

  • The troposphere is the lowermost layer of the atmosphere.
  • Its average height is 13 km
    • 8 km near the poles
    • 18 km at the equator
  • The thickness is greater at the equator because heat is transported to great heights by strong convectional currents.
  • The temperature in this layer, as one goes upwards, falls at the rate of 5°C / km
  • It reaches -45°C at the poles and -80°C over the equator
  • The fall in temperature is called ‘lapse rate’.
  • The troposphere is marked by temperature inversion, turbulence and eddies.
  • Almost all whether activities like rainfall, fog and hailstorm etc. happens in this layer
 
 

Tropopause

  • It acts as a boundary between troposphere and stratosphere.
  • This layer has a constant temperatures.
 
 

Stratosphere

  • It extend up to an altitude of 50 km from the earth’s surface.
  • The temperature rises to reach a level of 0°C at 50 km altitude.
  • This rise is due to the presence of ozonosphere
  • This layer is ideal for flying airplanes.
  • Sometimes, cirrus clouds are present at lower levels in this layer.
 
 

Ozonosphere

  • It lies at an altitude between 30 km and 60 km from the earth’s surface
  • This layer absorbs ultraviolet radiation.
  • The ozonosphere is also called chemosphere
 
 

Mesosphere

  • This layer continues upto an altitude of 80 km from the earth’s surface.
  • The temperature gradually falls to -100°C at 80 km altitude.
  • Meteorites burn up in this layer on entering from the space.
 
 

Thermosphere

  • In thermosphere temperature rises very rapidly with increasing height.
  • Ionosphere is a part of this layer.
  • It’s an electrically charged layer
  • It extends between 80-400 km.
  • Ionosphere helps in radio transmission.
  • Thermosphere is also known as exosphere
  • Person would not feel warm because of the thermosphere’s extremely low pressure.
  • The International Space Station and satellites orbit in this layer.
  • Aurora’s are observed in lower parts of this layer.
  • Light gases like helium and hydrogen float into the space from here.
 
Layers of Atmosphere
 

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