Layers of Atmosphere

Our planet earth is surrounded by a gaseous layer called Atmosphere which is divided into various other layers. The layer of Atmosphere is an integral topic for the preparation of competitive exams like SAT, SSC CGL, RRB or other scholastic exams. Hence, all the aspirants must thoroughly prepare for this topic. If you are looking for some quick revision or want to learn more about this topic then this blog is going to end your search!

What is the Atmosphere?

The atmosphere can be defined as a layer of gases that surrounds the planet earth or any other celestial body which comprises of a sufficient mass. From the surface of the earth, the atmosphere extends up to 1000KM. But, almost the entire mass of the atmosphere can be experienced within 32 KM because of the strong gravitational pull of the earth. This layer of atmosphere comprises of various gases at different proportion like Nitrogen 78% and Oxygen 21%, the rest 1% includes gases like Argon, Carbon dioxide, Neon, Helium etc. 

Now that you are familiar with the concept of atmosphere, let us study the various layers of the atmosphere.

Layers of Atmosphere 

There are 5 layers of the atmosphere, namely:

• Troposphere
• Stratosphere
• Mesosphere 
• Thermosphere
• Exosphere

Troposphere 

• Extending up to 18 km in height, it is the first of layer of the atmosphere at the equator and 8 km at the poles
• In the Troposphere, the temperature decreases with height, hence, the density of the air decreases with an increase in height i.e., lesser heat is absorbed
• The Troposphere contains more than 90% of the total gases of the atmosphere
• ‘Tropo’ means Change, as almost all the weather changes occur in this layer due to the formation of clouds from the water vapours  
• Tropopause: The maximum height where the temperature stops decreasing. The temperature here can go as low as -58 degree celsius

Why does the troposphere get warmer near the ground?
Despite the fact that sunlight strikes the Earth’s surface from top to bottom, the troposphere is heated most intensely there. The surface of the Earth is far more effective than the air at absorbing a variety of solar energy. The heated air packet expands as it rises, and when air expands, it cools. Because of this, the base of the troposphere is warmer than its base because air on Earth’s surface absorbs solar energy, warms up, and rises upward, where it cools down.

Stratosphere 

• This is the second layer of the atmosphere and ranges up to 50 KM above the Troposphere
• Out of all the layer of the atmosphere, Stratosphere is most beneficial as it absorbs the Ultraviolet (UV) radiations from the Sun because of the presence of ozone in it
• As compared to the layer beneath it, this layer warmer and has a temperature of around 4 degrees celsius 
• The layer provides ideal conditions for flying fighter jet planes as it is free from clouds and weather phenomena

What causes the stratosphere to be warmer than the troposphere?
The sun’s intense UV radiation is absorbed by ozone molecules in the stratosphere and transformed into heat. The stratosphere warms up as you ascend for this reason, unlike the troposphere.

Mesosphere 

• Extending to a height of 80 KM above the Stratosphere lie the Mesosphere
• It is one of the coldest layers of the atmosphere with a temperature rising up to -90 degree celsius
• Meteors burn up in this layer
• It is difficult to breathe in this layer as the air is thinnest with bare minimum pressure in it
• No aeroplanes, fighter jets, hot air balloons can fly this high to reach this layer

Why would the mesosphere make the blood boil in an unprotected astronaut?
Because the ozone layer that gives UV protection is in the stratosphere below, an astronaut travelling through the mesosphere would suffer severe burns from the sun’s ultraviolet rays. As they enter the atmosphere from space, meteorites ignite in this layer.

Thermosphere

• The Thermosphere is found exactly above the Mesosphere with a height of 640 KM
• The temperature in this layer increases with the height as the gas molecules present in this layer absorb the UV radiations and the X-rays from the sun
• Amongst all the layers of atmosphere, this layer helps in the long-distance communication as the electrically charged gas particles present in the Thermosphere reflect backs the radio waves from the Earth to space
• This layer also protects the earth from the huge meteors and satellites 

Exosphere 

• It is the outermost layer of the atmosphere and extends up to 640 KM of height
• The temperature of this layer is quite high and ranges between 300-degree celsius to 1650 degree celsius 
• As the height of the layer increases, it slowly merges into the interplanetary space
• The layer contains the least amount of gases like Oxygen, Argon, Helium etc. because the particles of the gases escape to space due to bare minimum presence of gravity  

Layers of Atmosphere Class 7

Layers of Atmosphere PPT

Layers-of-atmosphere from Todd Bloch

Layers of Atmosphere Diagram

Hopefully, this blog about layers of the atmosphere has equipped you with clear insights into the topic. To get a high score in the SAT exam you can get in touch with Leverage Edu. Our exclusive online learning platform and test prep guidance can push you towards a better SAT score!