Question

Write about the structure of atmosphere in detail.

Answer 1

Structure of Atmosphere: The layers of atmosphere differ from one another with respect to density and temperature. On the basis of chemical composition the atmosphere is mainly divided into Homosphere and Hetrosphere.

1) Homosphere-

• It extends upto 90 km.
• It is uniform in chemical composition.
•  It consists of three layers
  • Troposphere
  • Stratosphere
  • Mesosphere

Troposphere:

• Lower most layer of atmosphere
• Average height is 13 km although it is roughly 8 km.
• The thickness of troposphere is greater at equation due to upward transportations of heat by conventional currents. This layer consists of dust particles and water vapours.
• The temperature decrease with height in this layer at a rate ldegree for every 165 m. this is known as Normal Lapse Rate.
• It is layer is important for all biological activities besides that all climatic and weather conditions takes place in this layer.

Tropopause:

• The upper limit of troposphere separating it from stratosphere is called tropopause. It is very unstable at a thin layer and very thin layers of 1.5 km thickness.
• The temperature of tropopause is -80degree centigrade censius at equator and -40 degree centigrade at poles.
• The jet planes at the other activities occur in this layer.

Stratosphere:

• It extends upto 50km.
• It is thicker at poles then at equator.
• The temperature is almost constant in its lower portion upto 20 km and their it gradually increases upto 50 km due to the presence of Ozone which absorbs UV rays.
• The temperature rises in the upper limits of the stratosphere as there are no clouds, no conventional currents, no dust particles and the air moves in the horizontal direction. The upper’ limit of stratosphere is called stratosphere which has concentration of Ozone gas.

Mesosphere:

• It extends from 50 to 90 km.
• Temperature decreases with height in this layer and false upto minus 100 degree centigrade at a height of 80-90 km. this is due to the clouds in high latitudes.
• The upper limit of Mesosphere is called as Mesopause.

2) Hetrosphere-

• It has heterogeneous chemical.
• It consist of two layers
  • Ionosphere
  • Exosphere

Ionosphere:

•  It extends from 80 to 400 km above the mesopause.
• It contains electrically charged particles known as ions.

Exosphere:

• It is the uppermost layer of the atmosphere above the thermosphere.