Layers of the Earth’s Atmosphere

Layers of the Earth’s Atmosphere

• Atmosphere is a thick gaseous envelope that surrounds the Earth and extend thousands of Kilometers above the Earth’s surface.
• The main constituent of Earth’s surface comprised of mainly Nitrogen & Oxygen accounting 99% of the total volume of the atmosphere.
• There are five types of layers of the earth’s atmosphere based on its temperature. These are: 1) Troposphere 2) Stratosphere   3) Mesosphere   4) Thermosphere  & 5) Exosphere
• In this article, we will learn about these layers in detail along with their varying temperature. layers of the atmosphere in order.

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Layers of the Earth’s Atmosphere

 Troposphere (8km- 18km)

• This is the first layer of the Earth’s atmosphere.
• The height of troposphere is 16 km thick over the equator & 10 km thick at the poles.
• All “weather phenomena” occur in this layer only (e.g. fog, cloud, frost, rainfall e.t.c)
• Temperature decreases with height in this layer at the rate of 6.5 degrees /1000 metres which is called normal lapse rate.
• The upper limit of troposphere where the temperature stops decreasing is called tropopause.

Stratosphere (15 km-50 km)

• This is the second layer of the atmosphere. It extends to about 50 km.
• This layer is free from major weather phenomena and clouds and therefore this layer is considered ideal for flying of jet airways.
• The ozone layer that protects us from the harmful Ultraviolet radiations (UV) coming from the Sun, lies within the stratosphere at an altitude of 15 to 35 km above the earth’s surface.
• Above 50 km, the temperature starts declining and this region is called Stratopause.

Mesosphere (50-90 km)

• The Mesosphere layer extends to the height of 50-90 km.
• Temperature decreases with height. It reaches a minimum of -80 degree at an height of 80-90 km.
• This layer is considered as the coldest layer of the atmosphere.
• The upper limit of Mesosphere is called Mesopause.

Thermosphere (80 km-640 km)

• This layer lies at 80 km to 640 km above the surface of earth.
• Temperature increases rapidly with increasing height and reach upto 1480⁰ C.
• This layer is considered as the hottest layer of the atmosphere.
• This increase in temperature is because the gas molecules in this layer absorb the X-rays and Ultraviolet radiation of the sun.
• This result in the breaking of gas molecules into Positively and Negatively charged particles and therefore this layer is also known as Ionosphere.
• It also acts as a protective layer against meteorites coming towards the earth’s surface.
• Radio waves transmitted from earth are reflected back thus radio communication is possible in this layer.

   Exosphere (10,000 km)

• This is the uppermost layer of the atmosphere extending beyond the ionosphere.
• The density is very low and temperature becomes 5568⁰ C.
• This layer acts as a “transitional layer” between Earth’s atmosphere and Space.
• Most satellites orbit in the exosphere.

  About Ionosphere

• At heights of 80 km, the gas is so thin that free electrons can exist for short periods of time before they are captured by a nearby positive ion.
• This portion of the atmosphere is ionized and contains plasma which is referred to as the ionosphere.
• In this layer, the Ultraviolet (UV), X-Ray & Shorter wavelengths of solar radiation ionizes the atmosphere.
• The ionosphere layer is further divided in number of layers e.g. D-layer, E-layer & F-layer.
• It should be noted that the Short radio waves are absorbed by earth but reflected by the  E & F-layer whereas Long radio waves are reflected by D-layer. Layers of the Earth’s Atmosphere.

Frequently Asked Questions (FAQ’s)

Q1) What are the five layers of the atmosphere?

Ans. There are five types of layers of the atmosphere based on its temperature. These   are: 1) Troposphere 2) Stratosphere   3) Mesosphere   4) Thermosphere  & 5) Exosphere

Q2) Which is the hottest layer of the atmosphere?

Ans. Thermosphere can be considered as the hottest layer of the atmosphere. The temperature here can reach upto 1480⁰ C.

Q3) Which is the coldest layer of the atmosphere?

Ans. Mesosphere is considered as the coldest layer of the atmosphere. The temperature here can reach a minimum of -80⁰ C.

Q4) In which layer is Ozone layer present?

Ans. The ozone layer  lies in the Stratosphere at an altitude of 15 to 35 km above earth’s surface.