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What is the definition of Atmosphere?

The Earth's atmosphere is divided into five layers and several secondary levels. The primary layers include troposphere, stratosphere, mesosphere, thermosphere, and exosphere. They are arranged from lowest to highest depending on the altitude.

The atmosphere is the layer of gases that envelops or surrounds the planet Earth and it can be regarded as a celestial body due to its sufficient mass. There is a powerful gravitation attraction within 32km of the atmosphere which allows one to feel it practically. The atmosphere consists of various gases namely nitrogen at 78 percent and oxygen at 21 percent. The remaining 1 percent of the gases includes argon, carbon dioxide, neon and helium.

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 It acts as a barrier that protects the biosphere and outer ace from any harmful rays. It has no odor, color, or taste which is thoroughly combined and blended like a single gas. 

Contrary to popular belief, the present atmosphere was not directly produced during the early phases of the earth’s formation. Major changes that played a key role in the earth’s development include chemical breakdowns of solid materials, volcanic eruptions, and hot springs. 

The earth is usually protected from harmful solar rays because of the atmosphere. A greenhouse effect is created by trapping the long-wave terrestrial radiation (from the Earth's surface) and permitting short-wave radiation (from the Sun) to flow through. All living organisms on the earth require a certain temperature and frequencies of sun radiation for their biophysical processes and functioning.

The atmosphere stretches up to a thousand kilometers above the earth's surface. However, its mass can be felt within 32 km of the earth’s surface due to the planet's powerful gravitational attraction. Below are the gases that makeup earth’s atmosphere:

1)      Nitrogen-78%

2)      Oxygen-21%

3)      Other gases-1%

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Layers of Atmosphere

What are the Different Layers of the Atmosphere?

The Earth's atmosphere is divided into five layers, as covered in the section above. These gases are inherently without any color, odor and form. The names of the five layers are Troposphere, Stratosphere, Mesosphere, Thermosphere, and Exosphere. Each layer is arranged according to its unique temperature. These strata are responsible for maintaining the earth's living conditions, and their primary duty is to safeguard those conditions. Scientists at ISRO always monitor earth’s atmosphere and environment to safeguard the citizens. The atmosphere layers also shield or protect the planet earth from the sun's damaging UV radiation.

Troposphere:

The atmosphere layer that is closest to the surface of the earth is called the troposphere. It is nearly 18 km long near the equator, 13 km long in the mid-latitude, and 8 km long at the poles.

According to NASA estimates, the troposphere makes up for about 90% of the atmosphere's overall mass. The troposphere is responsible for the entire weather phenomenon. Typically, it consists of dust particles, clouds, water vapor, and other elements. Every aspect of the weather phenomenon is linked to this layer. The temperature of the troposphere  decreases as atmospheric altitude increases.

Stratosphere:

The Stratosphere is situated above the troposphere and stretches up to 50 km around the world in a defined manner. 

It is different from the others due to the presence of the ozonosphere. Ozone is a gas which is made up of three atoms, and is an extremely reactive oxygen molecule. It absorbs the high-frequency UV rays which also increases the layer's temperature.

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Mesosphere:

Mesosphere is located between 50 and 80 kilometres above the earth's surface. There is a uniform layer from the troposphere to the mesosphere. A layer of ions stretches from the upper barrier into another layer at the mesosphere's upper boundary. The ions in this layer have the ability to reflect radio waves benefitting the communication system. 

Thermosphere:

Thermosphere is a layer that extends from 80 kilometers to 480 kilometers in the atmosphere. The gas molecules in this layer absorb the short wave radiation emitted by the sun leading to a rapid increase in temperature. The density of the air is so low in this layer that the energy cannot be transferred easily and heat is not felt.

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Ionosphere:

The area in which ions are located is called the ionosphere. It is situated between the high thermosphere and the upper mesosphere.

The particles in this layer get ionised due to the absorption of cosmic rays, gamma rays, X-rays, and shorter wavelength UV radiation. The temperature in this stratum rises due to the friction caused by meteorites and approaching spacecraft . Atomic oxygen is the most frequent gas in this layer. Helium and hydrogen atoms are also prevalent. 

Exosphere

The exosphere layer is located above the stratosphere, and is the uppermost layer of the atmosphere.

Gases are relatively rare due to the lack of gravitational force, gases are relatively rare. Consequently, the density of the air is also low.

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There is change in pressure and density as the altitude decreases. However, the temperature doesn’t change regularly. If the temperature changes, concerning the distance, it is known as the Temperature gradient. The atmosphere of the earth is divided into five layers depending on the temperature gradient.

Conclusion

In our solar system, every planet has an atmosphere and few planets consist of the moons as well. Clouds, rain, wind and even cyclones can be seen in a few areas. With time, Earth’s atmosphere has evolved through a gradual release of various gases from the interior of the earth and also from the metabolic activities of various-life forms.