Atmosphere

An atmosphere is a blanket of gases that surrounds Earth. It is held near the surface of the planet by Earth’s gravitational attraction. Argon, oxygen and nitrogen from the three main constitutions of the atmosphere.

The atmosphere:

  • contains the air that we breathe
  • helps retain the sun’s heat and prevents it from escaping back into space
  • protects life from harmful radiation from the sun
  • plays a major role in Earth’s water cycle
  • helps keep the climate on Earth moderate

There is no boundary between the atmosphere and the outer space. The atmosphere gets less dense and denser until it “blends” into outer space. The Earth’s atmosphere is divided into five layers based on the temperature. In the next section let us discuss these different Earth’s atmosphere layers.

Layers of Atmosphere

About 80% of the mass of earth’s atmosphere is contained below 10 km altitude. The atmosphere of earth is mostly composed of many gases including nitrogen, oxygen, carbon dioxide. This helps protect living organisms from genetic damage by solar ultraviolet radiation, solar wind and cosmic rays.
The earth’s atmosphere is divided into layers based on the temperature field. These layers are:

  • Troposphere
  • Stratosphere
  • Mesosphere
  • Thermosphere
  • Ionosphere
  • Exosphere

Layers of Atmosphere

The hierarchical arrangement of various layers of the Earth’s atmosphere

Troposphere

It is the undermost layer of the earth’s atmosphere. At the base of the troposphere, the air is warmer. Density and air pressure also decrease with altitude.

Stratosphere

It is the 2nd layer of the atmosphere. It occurs at an altitude of fifty kilometres.

Mesosphere

It lies beneath troposphere and above the stratosphere. Temperature decreases with the altitude.

Thermosphere

It extends to six hundred kilometres high. Aurora and satellites occur in this layer. It starts just above the mesosphere.

The ionosphere

It is an abundant layer composed of ionized atoms, molecules and electrons that expand from about forty-eight kilometres above the surface overlapping into the mesosphere and thermosphere.

The exosphere

It is the upper limit of the earth’s atmosphere. It extends from the top of the thermosphere up to 10,000 km.

Watch this video to know everything about the air around us. Although, technically we call it the atmosphere – the circle of air. Learn how this atmosphere arranges itself in 4 layers above earth – troposphere, stratosphere, mesosphere, thermosphere, how the ozone layer protects us from the harmful UV rays of the sun, and why does it feel cold when we go up high in the air.


Gases in Atmosphere

The atmospheric composition of gas on Earth is largely conducted by the by-products of the life that it nurse.

Gases in Atmosphere

Dry air from earth’s atmosphere contains 0.038% of carbon dioxide, 20.95% of oxygen, 78.08% of nitrogen and 0.93% of argon.

 Atmosphere Gases

Traces of hydrogen, neon, helium, nitrous oxide, ozone and other “noble” gases, but generally a variable amount of water vapour is also present, on average about 1% at sea level.

Frequently Asked Questions

  1. Which of the following is the most abundant element in the Earth’s atmosphere?
    • Neon
    • Argon
    • Oxygen
    • Nitrogen
  2. Answer: Nitrogen

    Nitrogen is the most abundant element in the atmosphere. It makes up 78% of the Earth’s atmosphere

  3. Which layer of the atmosphere contains the ozone layer?
    • Exosphere
    • Stratosphere
    • Thermosphere
    • Troposphere
  4. Answer:Stratosphere

    The stratospheric ozone layer absorbs most of the sun’s ultraviolet light and thereby protects the earth.

  5. Which of the following instruments is used to measure the air pressure?
    • Seismograph
    • Voltmeter
    • Thermometer
    • Barometer
  6. Answer:Barometer

    A barometer measures barometric (atmospheric) pressure.

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