Introduction

Earth is the only place in the entire universe where life thrives. It is the only planet conducive to the survival of all living beings—ever wondered how that has been possible? It is due to the air that surrounds the Earth. This air is called the Earth’s atmosphere. We will look into the different layers in the structure of the atmosphere and how they all play a part in making it possible for life to grow on this planet.

The earth is surrounded by air that comprises the atmosphere of the earth. This atmosphere is made up of various gases, dust particles, and water vapour. The composition of the atmosphere changes according to time and place and is not static. 

The different gases that make up the structure of the atmosphere are as follows:

From the above table, you can understand that nitrogen and oxygen are the two primary gases in the atmosphere that make up 99% of the atmospheric air. 

Carbon dioxide is vital because it plays a significant role in the environment and the functioning of the ecosystem. Carbon dioxide traps radiation heat in the atmosphere and is responsible for the greenhouse effect. 

What are homosphere and heterosphere? 

The Homosphere and Heterosphere are the two layers that make up the structure of the atmosphere. The lower part of the atmosphere, up to about 100 KM, is called the homosphere. Heterosphere is above the atmosphere and constitutes the upper part of the atmosphere. 

Difference between the Homosphere and Heterosphere 

The concentration of gases in the Homosphere is consistent, but it varies a lot in the Heterosphere. 

The troposphere, stratosphere, and mesosphere are the regions that constitute the Homosphere. The Ionosphere and exosphere are part of the Heterosphere.

The Structure of the atmosphere is composed of the following layers:

 Troposphere

1. The troposphere is the lowest layer of the atmosphere that starts at the surface of the earth.
2. The meaning of the word troposphere is ‘changing sphere’. All the weather changes take place in this layer only. It contains 75% of the total air in the atmosphere of the planet and is made up of aerosols and water vapor.
3. The lowest part of the troposphere is called the boundary layer. This area is strongly influenced by the temperature, moisture, and wind through air mass transfer.
4. The height of the troposphere is approximately 8 km in the tropics, 6 km in the higher latitudes, and 17 km in the middle latitudes. The troposphere also sees a phenomenon called the Normal Lapse Rate.
5. This is the environmental temperature that decreases with the increasing height of the atmosphere.
6. The higher limit of the troposphere is called tropopause. It is the transitional zone. Here you find the characteristics of both the troposphere and stratosphere.

Stratosphere

1. The next in the structure of the atmosphere is the stratosphere. This layer above the troposphere spreads up to a height of 50 km from the Earth’s surface.
2. The air in this layer blows horizontally, which is why this is considered ideal for aircraft.
3. The temperature is almost the same in the lower part of this layer, up to a height of approximately 20 km. After that, it starts increasing slowly.
4. One of the distinct features of this layer is the presence of a layer of ozone gas found in the lower portion of the stratosphere.
5. It has a higher concentration of ozone in comparison to other parts of the atmosphere. As a result, it absorbs the maximum of the Sun’s ultraviolet radiations. 

 Mesosphere

1. The mesosphere is the third layer of the atmosphere above the stratosphere. Extending up to a height of 80 km, it is the coldest of the atmospheric layers.
2. The temperature starts decreasing with increasing height and reaches up to -100 degrees Celsius when at the height of 80 km.
3.  Meteors and falling stars are occurrences in this layer. The upper limit of the mesosphere is called the mesopause, which separates the mesosphere and Ionosphere. 

 Ionosphere  

1. This is the fourth layer of the atmosphere located above the mesosphere. The ionosphere gets its name from the electrically charged particles called ions that constitute this layer.
2. The lower part of the thermosphere is called the ionosphere. The ionosphere is the main reason why radio broadcasting has been possible.
3. Radio waves reflect back on the earth from here; hence, radio broadcasting is possible on Earth. 

 Exosphere

1. The next in the structure of the atmosphere is the exosphere which is the last layer of the atmosphere located above the ionosphere. It extends to approximately 400 km above the earth.
2. There is a lack of gravitational force in the exosphere, which is why gases are scarce in this area.
3. This results in air density being very low in this layer of the atmosphere. 

Conclusion

These are the constituents that form the structure of the atmosphere. All these layers have their own functions and are essential for the smooth functioning of the planet and for life to flourish on Earth. The different layers mentioned above have their special utility. The composition and structure of the atmosphere are such that it prevents harmful ultraviolet rays from entering the earth and help maintain the optimum temperature required to sustain life. The different elements in the earth’s atmosphere contribute in various ways for life to progress unhindered.