An atmosphere is the gases covering the planet that are held on by its gravity. These surrounding gases can be divided into a set of layers. Our planet earth has 5 layers of the atmosphere. These layers start from the ground level of earth and rise up to a certain height according to its temperature, pressure, composition, and other properties. From the ground level they are:
- Troposphere:- (0 -12 km) or (0 to 7 miles)
- Stratosphere:- (12 -50 km) or (7 to 31 miles)
- Mesosphere:- (50 -80 km) or (31 to 50 miles)
- Thermosphere:- (80 -700 km) or (50 to 440 miles)
- Exosphere:- (700 -10000 km) or (440 to 6200 miles)
Between the layers of the atmosphere, there are zones called ‘pause’. 5 layers of the atmosphere have 4 pauses, named as:
We know the simple meaning of ‘pause’ is ‘stop’. For example, tropopause means the end of the troposphere layer, the same as stratopause means the end of the stratosphere.
Though the earth’s atmosphere layers are made of the gases. Therefore before knowing layers of the atmosphere in order, here we will see the composition of the gases in the atmosphere.
Earth’s atmosphere composition
The atmosphere of the earth has been made of many gases and these gases are usually called ‘air’. How much amount of these gases are available in the earth’s atmosphere, is called the composition of the earth’s atmosphere.
Earth’s atmosphere composition or percentage of gases in the atmosphere by volume are given below:
- Nitrogen- 78.08%
- Oxygen- 20.95%
- Argon- 0.93%
- Carbon dioxide- 0.041%
- Water vapor- 0.0028%
- Neon- 0.0018%
- Other trace amounts of gases- such as Helium (He), Hydrogen (H2), Methane (CH4), Krypton (Kr), Ozone (O3), Xenon (Xe), and greenhouse gases.
These gases have some specific regions in the whole atmosphere. Ozone gas (O3) is found at a height of around 15 to 35 km in the stratosphere layer. Whereas Earth’s oxygen level or oxygen percentage in the atmosphere is around 20.95% by volume and is mostly found in the troposphere layer.
5 different layers of the atmosphere
Here we have mentioned Earth’s 5 layers of the atmosphere in order with the proper diagram. We have also given detail about the 4 pauses in the atmosphere.
The troposphere is the first and lowest layer of the atmosphere of the earth. It extends from the surface of the earth to an average height of 12 km. The troposphere contains more than 80% mass of the earth’s atmosphere.
We can say, this is our layer because we live in the bottom of this layer that is called the surface of the earth. This is the layer where we can experience the weather and seasons of the earth. So this layer also called weather layer.
Water vapor, clouds, moisture, and other weather associated winds all are found within this layer. At the height of 5 km from the earth’s surface, it contains 50% mass of the atmospheric gases. The temperature of this layer decreases with the height and it ranges from (25ºC to -60°C) from the surface to the tropopause zone.
The troposphere layer can be accessed by propeller-driven aircraft.
The tropopause is the transition zone of the troposphere and stratosphere layer. It locates at the top of the troposphere layer and bottom of the stratosphere layer. At this zone/height, the temperature stops decreasing. (‘tropo’ means ‘change’ and ‘pause’ means ‘stop’).
The stratosphere is the second layer of the atmosphere from the earth’s surface. It lies above the troposphere and below to the mesosphere. The stratosphere extends from 12 km to 50 km of the earth’s surface.
In this layer, the temperature rises with increasing the height and it ranges from (-60ºC to 4ºC) from the tropopause to the stratopause zone. Ozone(O3) is present in this layer. The ozone layer absorbs the ultraviolet radiation of the sun and increases the temperature of this layer.
This layer is free from clouds and other weather associated air turbulence. Because of this, it provides the best condition for the flying of jets and large airplanes.
Jet powered aircraft could reach the level of the stratosphere layer.
At about 50 km from earth’s surface temperature start falling again and is the pause zone of the stratosphere called stratopause. The stratopause is a transition zone and locates between the top of the stratosphere and bottom of the mesosphere layer.
It is the 3rd layer of the atmosphere from the earth’s surface and contains the region above the stratosphere and below the thermosphere. The mesosphere extends an altitude of 50 km to 80 km from the surface of the earth.
The temperature of this middle layer of the atmosphere decreases with altitude and ranges from (4ºC to -90ºC) from the stratopause to the mesopause zone. The mesosphere is the coldest layer of the atmosphere with an average temperature of -80ºC.
This layer helps us by burning up most of the meteors. The mesosphere layer can be accessed by rocket-powered aircraft.
Just below the mesopause, the mesosphere layer contains noctilucent clouds (night-shining clouds). These noctilucent clouds are the highest clouds of the atmosphere and it is made up of ice crystals.
At about 80 km from the earth’s surface temperature starts rising again and this is the end of the mesosphere called mesopause. It locates between the mesosphere layer and the thermosphere layer.
The thermosphere is the 4th layer of the atmosphere from the earth’s surface and is the 2nd highest layer. The thermosphere lies between the mesosphere and the exosphere layer. It extends from a height of 80 km to 700 km in the atmosphere of the earth.
The gases of this layer absorb X-rays and ultraviolet radiation of the sun. Because of this absorption of radiation, it raises the temperature of the layer at around 1500 degrees Celcius. Hence in thermosphere layer temperature ranges from (-90ºC to 1500ºC) from the mesopause to thermopause.
The thermosphere layer protects us from meteors and obsolete satellites by burning up with its high temperature. So this layer burns up the space debris coming towards earth.
Sometimes aurora lights can be seen in the thermosphere layer.
The high temperature of this layer breaks the molecules of the gases into positive and negative charged particles or ions. So the thermosphere layer is also called the ionosphere. Mainly ionosphere extends at about 80 km to 550 km above the earth’s surface. These ions of ionosphere reflect the radio wave towards space which results in high range radio communications.
International space station (ISS) orbits at a lower height of 300 km to 400 km from the earth’s surface so this is the layer where ISS located.
The transition zone of the end of the thermosphere and start of the exosphere is thermopause.
It is the highest layer of the atmosphere and lies above the thermopause. It is located at an altitude of 700 km to 10000 km from the earth’s surface.
This layer has low-density gases like hydrogen, helium, oxygen, nitrogen, and carbon dioxide. Atoms and molecules of these gases are free-moving particles and usually do not collides with each other. These particles can travel hundreds of kilometers without a single collision.
The exosphere layer contains many of the satellites that are orbiting around the earth.
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