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Composition and Structure of the Atmosphere

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A gaseous blanket that surrounds the Earth and includes the air we breathe is referred to as an atmosphere. The gravitational pull of the earth keeps it close to the planet’s surface. Argon, oxygen, and nitrogen are the three major components of the atmosphere. There is no separation between the atmosphere and outer space. The atmosphere eventually thins and densifies until it merges with space.

Composition of the Atmosphere

A planet’s atmosphere is a layer of gases that surrounds it and is held in place by gravity. A planet’s atmosphere is preserved when gravity is high, and the temperature of the atmosphere is low.

The atmosphere of our planet is made up of 78 percent nitrogen, 21 percent oxygen, 0.9 percent argon, 0.04 percent carbon dioxide, and many other gases. Furthermore, there is a variable amount of water vapor in the atmosphere (around 1% at sea level), which decreases with height. The fundamental cause of the greenhouse effect is carbon dioxide gas. Incoming sun energy does not pass through it, but outgoing terrestrial radiation does. Some terrestrial radiation is absorbed, while some are reflected back to the planet’s surface.

Dust particles can also be seen in the air. Sources include fine dirt, smoke-soot, pollen, dust, and dissolved meteoric particles. Dust and salt particles act as hygroscopic nuclei, allowing water vapor to condense and condensate, resulting in clouds.

Composition of the Atmosphere

Nitrogen

It is the chemical element with the atomic number 7, an unreactive gas that accounts for approximately 78% of the earth’s atmosphere. 

Oxygen

It is a transparent, scentless reactive gas, with the atomic number 8 chemical element, and is the life-sustaining component of air. It is necessary for burning. Oxygen comprises 21 percent of the atmosphere.

Carbon dioxide

It is a gas created by the combustion of carbon and organic molecules, as well as respiration. It occurs naturally in the atmosphere and is absorbed by plants during photosynthesis.

Water vapor

It is a gaseous form of water that is invisible to the human eye. When water evaporates from surfaces such as oceans, lakes, and rivers, water vapor is formed. Temperature, humidity, and other environmental conditions may all influence the amount of water vapor in the atmosphere.

Dust Particles

Dust is made up of small solid matter particles. On Earth, it mostly consists of particles in the atmosphere that are transported by wind, volcanic eruptions, and pollutants. 

Ozone Gas

It is found between 10 and 50 kilometers above the earth’s surface and serves as a sieve, absorbing UV (ultraviolet radiation) from the sun. Ozone prevents damaging radiation from reaching the earth’s surface.

Structure of Atmosphere

The structure of the atmosphere is divided into five levels based on temperature. These layers are as follows:

  1. Troposphere
  2. Stratosphere
  3. Mesosphere
  4. Thermosphere
  5. Exosphere

Troposphere

The troposphere is the atmosphere’s lowest layer. It rises from ground level to more than ten kilometers above sea level. The troposphere holds 75% of the air in the atmosphere. Because it contains 99 percent of the water vapor in the atmosphere, this layer is where most clouds originate. As you fly higher into the troposphere, the temperature, and air pressure decrease. As it rises, an air packet expands. As it expands, the air cools. Because the air on the Earth’s surface absorbs the sun’s energy, heats up, and then cools down as it rises, the troposphere’s base is warmer than its top.

Stratosphere

The stratosphere is positioned above the troposphere and extends from the top of the troposphere to approximately 50 kilometers above the ground. The ozone layer is found in the stratosphere. The ozone molecules in this layer absorb the Sun’s high-energy ultraviolet (UV) light and convert it to heat. As a result, unlike the troposphere, the stratosphere warms up as one ascends.

Mesosphere

The Mesosphere is located above the stratosphere. It is the coldest layer in the atmosphere. The mesosphere extends from 50 to 80 kilometers above the Earth’s surface. The temperature drops as you travel higher in this stratum. The temperature decreases to -100 degrees Celsius at 80 kilometers. Meteors are destroyed in this stratum. The Mesopause is the highest border between the Mesosphere and the Thermosphere.

Thermosphere

The thermosphere is located above the mesosphere and is characterized by rising temperatures as one ascends. The temperature rises due to the absorption of powerful UV and X-Ray energy from the sun. This layer’s air, on the other hand, is so thin that it appears rather cold to us! Satellites orbit the Earth within the thermosphere. Temperatures in the upper thermosphere can vary from 500 to 2,000 degrees Celsius or more. Northern and Southern Lights, known as Auroras, occur in thermosphere.

Ionosphere

The ionosphere, unlike other layers of the atmosphere, is not a distinct layer. The ionosphere is a collection of mesosphere and thermosphere locations where high-energy solar radiation has stripped electrons from their parent atoms and molecules.

Exosphere

It is the atmosphere’s outermost layer. The exosphere is an area of space from which molecules and atoms can escape. It can be seen from the top of the thermosphere for a distance of 10,000 kilometers.

Structure of the Atmosphere

Frequently Asked Questions on Composition and Structure of the Atmosphere:

1. What is the composition of the atmosphere?

Ans:

The atmosphere of our planet is made up of 78 percent nitrogen, 21 percent oxygen, 0.9 percent argon, 0.04 percent carbon dioxide, and many other gases.

2. Explain the structure of the atmosphere.

Ans:

The structure of the atmosphere is divided into five levels based on temperature. These layers are as follows:

  1. Troposphere
  2. Stratosphere
  3. Mesosphere
  4. Thermosphere
  5. Exosphere

3. What is Ionosphere?

Ans:

The ionosphere, unlike other layers of the atmosphere, is not a distinct layer. The ionosphere is a collection of mesosphere and thermosphere locations where high-energy solar radiation has stripped electrons from their parent atoms and molecules.

4. What is Thermosphere?

Ans:

The thermosphere is located above the mesosphere and is characterized by rising temperatures as one ascends. The temperature rises due to the absorption of powerful UV and X-Ray energy from the sun. This layer’s air, on the other hand, is so thin that it appears rather cold to us! Satellites orbit the Earth within the thermosphere. Temperatures in the upper thermosphere can vary from 500 to 2,000 degrees Celsius or more. Northern and Southern Lights, known as Auroras, occur in thermosphere.

5. What is Ozone Gas?

Ans:

It is found between 10 and 50 kilometers above the earth’s surface and serves as a sieve, absorbing UV (ultraviolet radiation) from the sun. Ozone prevents damaging radiation from reaching the earth’s surface.



Last Updated : 05 Oct, 2023
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