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maximum heat and protects us from excessive COMPONENTS OF THE ATMOSPHERE
heating through the day and maintains a certain The earth’s atmosphere is mostly nitrogen that is
temperature level at night. 78% to be exact, 21% of the atmosphere is the
Stratosphere oxygen that we breathe, 0.9% argon and 0.04%
The stratosphere is just above the troposphere. It carbon dioxide. Even though there is so little
starts from 12 kms above the earth’s surface to carbon dioxide in the atmosphere, it is very
around 48-54 kms above the earth’s surface. powerful and most of the climate change is
Here, there are unusually high clouds called happening because of changes in a tiny percent-
nacreous clouds, the ozone layer and even a few age of the atmosphere but it affects a lot. The
aircraft, usually the jets. This is the layer which atmosphere, also has water vapour which is
contains the ozone layer. sometimes as high as 5% of the atmosphere in
The temperature in the stratosphere gets warmer the wettest places.
as we go up due to the absorption of ultraviolet Escaping
radiation in the ozone layer. radiation
Absorbed
Mesosphere Reflected
This third layer extends upto a height of 80 kms.
Here, the temperature starts decreasing with Absorbed by Radiation
atmosphere and
height and reaches about –100°C at the end of Earth absorbed by
greenhouse
the mesosphere. Meteorites burn up in this layer Deforestation Oil and gases
CFCs Greenhouse
as they enter from space. petrol gases and
engines
fossil fuels
Thermosphere
The thermosphere is the next layer also called the
ionosphere because of the presence of ions in Air is actually a mixture of various gases. All
this layer. It starts from 80-85 kms up until animals and plant life are dependent on the air
490 kms to 900 kms. The International Space all around. Nature maintains a good balance of
Station orbits in this layer. This is where we find the gases present in the atmosphere apart from
the auroras that people see from the earth near the mess humans have made with respect to
the North and South poles. The size of the global warming due to the pollution emitted from
thermosphere depends on how hot the sun is at various factories vehicles and nuclear testing.
a time. Temperature here increases drastically, SIGNIFICANCE OF THE ATMOSPHERE
but there is no proper way to calculate this; The atmosphere is of great significance for the
because of the presence of very few molecules in earth. It acts as a blanket and protects us from
this layer and also that they’re moving rapidly. the harmful ultraviolet rays of the sun. The
There are no clouds in this layer. carbon dioxide content, apart from helping the
Exosphere plants to produce food, also helps in keeping the
This is the uppermost layer which extends to a earth warm by absorbing heat. The presence of
height of about 1600 kms and merges with the oxygen and nitrogen is essential for both animal
interplanetary space. The air here is very thin and plant life. The water vapour in the atmo-
containing gases like helium and hydrogen, that sphere leads to precipitation and influences
float into the space from here. weather and climate.
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