ENVTPONMENT EXAM
80 klords
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short note
the Eartho Brospher
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Answer:
Answer:
Air is surrounded us, but we can not see it and the air is a mixture of various gases.
Interesting factors about air
In addition to oxygen, the air you breathe consists of lots of other gases.
Just about 21% of the air is made up of oxygen.
About 78% of the air you intake consists of nitrogen gases.
Small quantities of other gases, such as methane, argon and carbon dioxide, are also present.
On Earth in the absence of oxygen, animals and plants can not survive.
Although air is mostly gas, it contains tonnes of small particles as well. These atmospheric particles are termed as aerosols.
When the wind blows certain aerosols, including dust & pollen, are taken naturally. But the air from power plants, car exhaust can also hold smoke, soot & other particles. Those were key contributors to the pollution of the air.
In addition to sunlight, plants use carbon dioxide gas to generate food and oxygen too. The process is known as photosynthesis.
The air in our environment is the insulation that prevents the Planet from being too hot or too cold.
A kind of gas in the air, namely ozone safeguards us from many radiations as well.
The air in the atmosphere will protect us from meteoroids. They rub against the air as meteoroids enter our environment, and are also burned into tiny pieces once they reach Earth.
What is the atmosphere?
The atmosphere is a protective layer of gases that protects all life on Earth, keeps temperatures within a relatively small range and blocks harmful radiations from the sun.
Various layers of the atmosphere
There are five distinct layers in the atmosphere which are determined by the temperature changes that occur with increasing altitude. The Earth’s atmosphere layers are divided into five different layers, as follows.
Troposphere
The lowest layer in the atmosphere is the troposphere.
Starting from ground level, it extends upwards to about 10kms above sea level.
The boundary level is considered as the lowest portion of the troposphere. The tropopause is considered as the topmost layer.
Seventy-five percent of all the air in the atmosphere is in the troposphere.
Most clouds appear in this layer because 99 percent of the water vapour in the atmosphere is found here.
Air pressure and temperature drop as you go higher in the troposphere.
Stratosphere
Just above troposphere lies the stratosphere that extends from the top of the troposphere to about 31 miles above the ground.
The ozone layer lies within the stratosphere. In this layer, ozone molecules absorb high-energy ultraviolet light from the Sun and turn it into heat.
As a result, the stratosphere, unlike the troposphere, gets warmer the higher you go.
Mesosphere
The mesosphere is above the stratosphere and rises to a height of about 53 miles from the earth.
Here, the temperature gets cooler as you rise up through the mesosphere.
The coldest parts of our atmosphere are located in this layer and can reach – 90 ° C.
Thermosphere
Thermosphere lies above the mesosphere and this is a region where the temperature increases as you go higher up.
Due to the absorption of energetic ultraviolet and X-Ray radiation from the sun, the temperature increase is caused.
The air in this layer is so thin it would feel absolutely freezing.
Exosphere
The final frontier of the gaseous envelope of the Earth is the exosphere.
The air in the exosphere is continuously but steadily escaping out of the Earth’s atmosphere into outer space.
There is no straight cut upper limit where the exosphere eventually fades away into space.