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Layers Of Atmosphere And Its Composition

Layers Of Atmosphere

What are the layers of the atmosphere? What does our atmosphere consist of? The atmosphere is a thick envelope of gas that surrounds the earth and extends thousands of miles above the earth’s surface. Most of the life on Earth exists because of the atmosphere around us. The atmosphere affects the topography, vegetation, soil, and climate of the earth in several ways. There are a total of five layers in the atmosphere of the earth. The Layers of atmosphere along with their composition have been provided in this post. 

Composition of the Atmosphere

Do you know that the atmosphere is a mixture of several gases responsible for the life surviving on earth? It contains a huge amount of solid and liquid particles that are collectively known as aerosols. Pure dry air consists mainly of Nitrogen, Oxygen, Argon, Carbon Dioxide, Hydrogen, Helium, and Ozone. Besides, water vapor, dust particles, smoke, salts, etc. are also present in the atmosphere.

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The atmosphere is composed of:

  • Nitrogen (78.09%),
  • Oxygen (20.95%),
  • Argon(0.93%),
  • Other gases(0.03%)
  • Air pressure

Air pressure

  • The pressure falls rapidly as we go up the layers of the atmosphere. The air pressure is generally highest at sea level and decreases with height.
  • When the areas with high temperatures get heated, a low-pressure area is created. Low pressure is associated with cloudy skies and wet weather.
  • The lower temperature areas have cold air. Heavy air sinks and creates a high-pressure area. High pressure is associated with clear and sunny skies.

Layers of Atmosphere

Our atmosphere is divided into five layers starting from the earth’s surface. These are Troposphere, Stratosphere, Mesosphere, Thermosphere, and Exosphere.

Troposphere

  • It is the lowest layer of the atmosphere.
  • It extends up to a height of 8 Kms at poles and 18 Kms at the Equator.
  • All the weather phenomena are confined to Troposphere (e.g. fog, cloud, frost, rainfall, storms, etc.)
  • Temperature decreases with height in this layer roughly at the rate of 6.5° per 1000 meters, which is called the normal lapse rate.
  • The upper limit of the troposphere is called tropopause which is about 1.5 km.
  • Dust particles, water vapor, and other impurities are found here
  • This layer keeps the earth warm as it absorbs the maximum heat radiated by the earth’s surface being the densest and lowest layer of the atmosphere.
  • The air we breathe exists here.
  • Tropopause – is the layer that separates the troposphere from the stratosphere. In the troposphere, the temperature generally decreases with height, whereas above the tropopause, the temperature no longer decreases.

Stratosphere

  • The stratosphere is more or less devoid of major weather phenomena but there is a circulation of feeble winds and cirrus clouds in the lower stratosphere.
  • It extends up to a height of 50 km.
  • Jet aircraft fly through the lower stratosphere because it provides conducive flying conditions.
  • The ozone layer lies within the stratosphere mostly at the altitude of 15 to 35 km above the earth’s surface.
  • The ozone layer acts as a protective cover as it absorbs ultraviolet rays of solar radiation.
  • Depletion of ozone may result in a rising temperature of the ground surface and a lower atmosphere.
  • The temperature rises from -60°C at the base of the stratosphere to its upper boundary as it absorbs ultraviolet rays.
  • The upper limit of the Stratosphere is called stratopause.

Mesosphere

  • This is the third layer of the atmosphere and lies above the stratosphere.
  • The mesosphere extends to the height of 50 – 90 km.
  • Temperature decreases with height. It reaches a minimum of -80°C at an altitude of 80-90 km
  • It is the coldest layer of the atmosphere.
  • The upper limit is called menopause.
  • Meteorites burn up in this layer on entering from space.

Thermosphere/Ionosphere

  • It lies at 80 km to 640 km above the earth’s surface.
  • It is also known as the Ionosphere.
  • Temperature increases rapidly with increasing height.
  • It is an electrically charged layer. This layer is produced due to the interaction of solar radiation and the chemicals present, thus disappearing with the sunset.
  • Radio waves transmitted from the earth are reflected by the earth by this layer.
  • There are several layers in the thermosphere e.g. D-layer, E-layer, Flayer, and G-layer.
  • Radio waves transmitted from the earth are reflected by the earth by these layers.
  • This layer contains electrically charged air that protects the Earth from falling meteorites as most of them burn out in this region.

Exosphere

  • This is the uppermost layer of the atmosphere extending beyond the ionosphere.
  • The density is very low and the temperature becomes 5568°C.
  • This layer merges with outer space.
  • Light gases like helium and hydrogen float into space from here.
  • It extends from the top of the thermosphere up to 10,000 km (6,200 mi).

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