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Explian the four layers of atmosphere

What are the different layers of Atmosphere?

The Earth is surrounded by the atmosphere, which is the body of air or gasses that protects the planet and enables life. Most of our atmosphere is located close to the Earth's surface where it is most dense. The air of our planet is 79% nitrogen and just under 21% oxygen; the small amount remaining is composed of carbon dioxide and other gasses.

The atmosphere is divided into five different layers.They are:

      (i)   Troposphere
     (ii)   Stratosphere
     (iii)  Mesosphere
     (iv)  Thermosphere
      (v)  Exosphere

(i) Troposphere

Troposphere is the closest layer to the Earth’s surface.Its height above the Earth’s surface varies from place to place,about 8 kilometer over the poles and 18 kilometer over the equator.Troposphere contains 75% of the atmosphere’s gases and large amounts of water vapor and dust.Layer is warm neat the surface of Earth.The temperature within this layer decreases with increase in the height at a rate of 1oc per 165 cm.The weather and all its related activities such as rain,storm and thunder occur in this layer.

(ii) Stratosphere

Stratosphere stretches beyond the troposphere to about 50 kilometer, above the Earth’s surface.It is calmer than the troposphere and has little water vapor.This is the ideal layer for flying aircraft because no weather phenomena happen in this layer.The stratosphere holds about 90% of all the ozone,which protects us from harmful ultraviolet sun rays.

(iii) Mesosphere

Mesosphere stretches from about 50 to 80 or 85 kilometer above the Earth.It is much thinner and colder because there is little gas to absorb the Sun’s surface to absorb the heat radiated by the Earth.Mesosphere plays an important part in slowing down meteorites that hurtle into the atmosphere.

(iv) Thermosphere

The Thermosphere is the layer above the mesopause. The gases of the thermosphere are even thinner than those in the mesosphere, but they absorb ultraviolet light from the sun. Because of this, the temperatures rise to 3,600 ºF (2,000 ºC) at the top. This is at a height of 430 miles (700 km) of the Earth's surface. In the thermosphere is a separate layer, the Ionosphere. This layer extends of 62 miles(100 km) to 190 miles(300 km) of the earth's surface.

(v) Exosphere

Exosphere is the outer most layer of the atmosphere that is more than 1000 km above the Earth’s surface where the gases get very thin. At this altitude,gravitational pull of the Earth becomes very weak and the atmosphere gradually tides into the outer space.


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