The atmosphere is composed of various layers defined by temperature: the troposphere, stratosphere, mesosphere, thermosphere, and exosphere. It contains a mixture of gases such as nitrogen, oxygen, carbon dioxide, and water vapor. The atmosphere plays an important role in regulating Earth's climate by trapping heat and blocking harmful solar rays, making the planet habitable for life.

1. Structure and composition of atmosphere
Contents…
I. Earth system
II. Structure of atmosphere
1. Troposphere
2. Stratosphere
3. Mesosphere
4.Thermosphere
5. Ionosphere
6. Exosphere
III. Composition of atmosphere
IV. Functions of atmosphere

2. 1. The atmosphere is an important part of what makes Earth
livable.
2. Atmosphere is the thin layer of air that surrounds the
earth.
3. It is made up of various gases such as oxygen, nitrogen,
carbon dioxides, dust particles and water vapour.
4. It blocks some of the Sun's dangerous rays from reaching
the Earth.
5. It traps heat, making Earth a comfortable temperature.
and the oxygen within our atmosphere is essential for
life.
6. The atmosphere help us to protect from the harmful
rays of the sun.

3. I. Earth system

4. II Structure of atmosphere
The atmosphere is a collection of gases that
makes the Earth liveable.
The mixture of gases around
the earth.

5. Based on its temperature,
• Troposphere
• Stratosphere
• Mesosphere
• Thermosphere
• Ionosphere
• Exosphere-500 km
above the Earth's surface.

6. 1. Troposphere
• This is the lowest part of the atmosphere
• It extend from 0-18 kms.
• The troposphere contains about 75% of all of the air in
the atmosphere, and almost all of the water vapour.
• The actual change of temperature with height varies
from day to day, depending on the weather.
• The decrease in temperature with height is a result of
the decreasing pressure.
• The lowest part of the troposphere is called the
boundary layer.
• This is the most important layer of the atmosphere.

7. 2. Stratosphere
• This extends upwards from the troposphere to about 30
km.
• It contains much of the ozone in the atmosphere.
• The increase in temperature with height occurs because of
absorption of ultraviolet (UV) radiation from the sun by
this ozone.
• Temperatures in the stratosphere are highest over the
summer pole, and lowest over the winter pole.
• By absorbing dangerous UV radiation, the ozone in the
stratosphere protects us from skin cancer and other health
damage.
• However chemicals which were once used in refrigerators,
spray cans and fire extinguishers have reduced the
amount of ozone in the stratosphere.

8. 3. Mesosphere
• The region above the stratosphere is called the
mesosphere.
• The region 30km to 50 km above the surface of
the earth, above the troposphere and
stratosphere.
• The main chemical constituents are nitrogen,
oxygen.
• Here the temperature again decreases with
height, reaching a minimum of about -90°C.
• It is the coldest of the atmospheric layers.

9. 4. Thermosphere
• The thermosphere is the layer of the earths
atmosphere directly above the mesosphere.
• 50-400 km above the earths surface.
• The temperature increase is caused by the
absorption of energetic ultraviolet and X-Ray
radiation from the sun.
• Temperatures are highly dependent on solar
activity and can rise to 2000°C.
• The temperature of the thermosphere varies
between night and day .

10. 5. Ionosphere
• The region of the atmosphere above about75
- 1000km is also caused the "ionosphere“.
• It is ionized by solar and cosmic radiation.
• It has large number of electrically charged
atoms.
• The ionosphere reflects and absorbs radio
waves, allowing us to receive short waves.

11. 6. Exosphere
• It is the upper most layer.
• It extends upto 1600 km.
• It contains mainly Helium and hydrogen .
• Communication on earth depends on satellites.
• Satellites transmit information used for television
shows, radio broadcasts, data and photos used in
weather reports, and long distance telephone
calls.

12. III Composition Of Atmosphere

13. IV Functions of atmosphere
• It maintains the heat balance on the earth by
absorbing the IR radiations.
• The gaseous constituents play an important
role in sustaining life on earth.
• For example,
• oxygen supports life of living organisms.
• Carbon- di oxide is essential for
Photosynthetic activity of plants.
• Nitrogen is essential nutrient for plant
growth.