What is atmosphere? | Earth’s Atmospheric layers & structure

Do you know what is atmosphere? Earth is the only planet out of the 8 planets of the Solar System where life has been found in the search till now. The main reason for this is the oxygen, which is considered to be the vital air for organisms is present in the Earth's atmosphere. Earth is the only planet whose bioactive environment is favorable. Evidence of life on the rest of the planets has not yet been found by scientific discovery.

It is not that other planets do not have an atmosphere. According to scientific discovery, other planets of the solar systems also have an atmosphere. But the atmosphere there is not compatible with the Earth's atmosphere. Right now, research is being done by scientists on the planet Mars. Because the atmosphere of Mars resembles that of Earth

what is atmosphere
what is atmosphere

According to scientists, the fact found on Mars so far suggests that there is the most possibility of life and water on Mars. It is necessary for humans and other organisms to have water along with oxygen in the atmosphere. In this article, we will try to tell you what is atmosphere and why it is important for life. As well as, we will discuss the existing gases in the atmosphere of the Earth, the layers of atmosphere, etc. So let's first know what is atmosphere?

What is atmosphere?

The thick layer of air around the earth is called the atmosphere. Earth is divided into the atmosphere, lithosphere, and hydrosphere. In which the atmosphere is made of air, the lithosphere is made of solids, and the hydrosphere is made of water. There is no definite measure of how far the atmosphere extends, but it is certain that it is spread over several hundred miles around the earth.

Air is very important for the survival of animals and plants. It also has a profound effect on the weathering of the Earth's surface. Many types of physical and chemical activities are performed due to the air of the atmosphere. Many views of the atmosphere, such as rainbow, lightning and whirling, north polar light, south polar light, halo, etc. are produced by light or electricity.

The density of the atmosphere is not the same. As the altitude rises above the surface of the Earth, the density of the atmosphere also decreases. The difference in temperature also causes a difference in the density of the atmosphere. Air pressure at sea level is equal to the pressure of a column of 760 millimeters of mercury.

Earth is warmed by the sun's small radiation energy. The radiation of long-lived physical energy from the Earth is absorbed into the atmosphere. Due to this, the temperature of the atmosphere remains between 68 ° C to 55 ° C. Ultraviolet light above 100 km converts oxygen molecules into ions and atoms into electrons. This is why this layer of atmosphere is called the ionosphere. At night, these ions or electrons then merge together into a molecule or atom, causing green and red lines to appear in the night light.

See Also: What is Climate change?

Atmosphere structure and composition


Percent volume







Carbon Dioxide















Small amount

Earth’s Atmospheric layers

The Earth's atmosphere is divided into 5 layers based on density, altitude, and temperature. They are as follows:


The lowest layer of the atmosphere is the troposphere. This region is most important for the biosphere ecosystem as all weather related events occur in it. The air temperature decreases at an average rate of 1 ° C per 165 m elevation. This is called the normal heat collapse rate.

Its height is 8 to 10 km at the pole and about 18 to 20 km at the equator. This layer consists of nitrogen, oxygen, carbon dioxide, water vapor, and dust particles. It is estimated that about 95% of the Earth's atmosphere is in the troposphere. The topmost layer of the troposphere is called the Tropopause.


Above the troposphere of the Earth, is the stratosphere. This layer is about 20 to 50 km above the Earth's surface. Ozone, nitrogen, oxygen, etc. are the main gases in this layer. Ozone gas is found in the stratosphere for about 30 to 60 kilometers. The topmost layer of the stratosphere is called Stratopause.

As the height of this layer increases, the temperature increases. This sequence continues until the Stratopause. Since there is negligible humidity at this level, clouds form less. Especially in this layer, the formation of the ozone layer in the presence of ultraviolet radiation from 20 to 30 km continues. Hence this layer is also called ozonosphere. This layer absorbs 99% of ultraviolet solar radiation. As a result, harmful radiation does not reach the Earth. This creates an environment conducive to the survival of animals and plants on Earth.


The atmospheric layer above the stratosphere is called the Mesosphere. This layer is about 50 to 80 km above the Earth's surface. At this level, the air layer becomes thinner. The temperature decreases at this level as altitude increases. This is the coldest layer.

Hot gas lines emanating from the meteor appear at this level. The topmost layer of the Mesosphere is called the Mesopause. Strong winds blow at this layer. Such winds flow from west to east in winter and from east to west during the rainy season.


The atmospheric layer above the Mesosphere is called the Thermosphere. This layer is about 80 to 720 km above the Earth's surface. At this level, the air layer is thinner and the air is less. As the effect of solar radiation is more at this level, the temperature also increases as the height increases.

At the bottom of this layer, molecules of nitrogen, oxygen, etc. break down into atoms, while in the upper part; it consists mainly of helium and hydrogen. This is called the ionosphere because at this stage the gas molecules transform into ions. The topmost layer of this layer is called Thermopause.


The atmospheric layer above the thermosphere is called the Exosphere. This layer is about 720 km above the Earth's surface. This layer is also called the boundary zone. It is the topmost layer of the Earth's atmosphere.

At this layer, even though the air is negligible, air molecules and atoms move very rapidly. These molecules and atoms are so fast that they cannot be affected by the gravitational pull of the Earth. Molecules and atoms that are free from gravity fly into space.

See Also: What is Global Warming?

Atmospheric humidity

The amount of invisible water vapor present in the atmosphere is called atmospheric humidity. This humidity reaches the atmosphere by various forms of evaporation from the earth. Humidity is of paramount importance in climatology because various forms of precipitation, atmospheric storms, and cyclones, etc. are based on this.

Atmospheric humidity depends on the water vapor present in the air. This water vapor remains in the lower levels of the atmosphere. Its quantity is not the same in all places and always. There are differences in time and place. This water vapor is formed by the evaporation of water of river, pond, lake, ocean, etc.

Atmospheric pressure

Atmospheric pressure is the force exerted on a unit area of a surface in the Earth's atmosphere by the weight of air above it. In most circumstances, the approximate atmospheric pressure is estimated by the weight of the air above it at the measurement point. Low-pressure areas have a lower atmospheric mass above those locations, while high-pressure areas have a higher atmospheric mass above those locations. Similarly, as the altitude increases, the atmospheric mass decreases above that level, so the pressure decreases with increasing altitude. The atmospheric pressure at sea level is equal to the pressure of 760 mmHg. The air pressure measuring unit is millibar. The average atmospheric pressure at the seabed is 1013.25 millibar (MB).

Conclusion:  The atmosphere is very important to maintain life on Earth, so we will have to maintain the balance of the atmosphere for balancing the ecosystem.

In the end

In today's post, you have learned what is atmosphere, as well as the structure of atmosphere, Earth’s Atmospheric layers, atmospheric pressure, etc. Hope you all like this article. You are requested; please share this article so that it can reach as many people as possible. We look forward to your support so that I can write more new articles.

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