About Atmosphere and Thermosphere

1. Atmosphere

2. What is the Atmosphere?
The atmosphere is the blanket of
gases which surrounds Earth. It is
held near the surface of the planet by
Earth's gravitational attraction.

3. Without the atmosphere there could be no
life on Earth.
The atmosphere:
• contains the air we breathe;
• protects life from harmful radiation from
the Sun;
• helps keep the planet's heat from the Sun
from escaping back into space;
• is a major element of the water cycle;
• keeps the climate on Earth moderate
compared to that of other planets.

4. • The atmosphere is made up of a mixture of gases,
mostly nitrogen, oxygen, argon and carbon
dioxide.
• It reaches over 500km above the surface of the
planet.
• There is no exact boundary between the
atmosphere and outer space.
• Atmospheric gases become thinner the higher up
you go.
• The atmosphere just keeps getting less and less
dense, until it "blends" into outer space.

5. The atmosphere is divided into four
layers based on temperature:
• the troposphere,
• stratosphere,
• mesosphere, and
• thermosphere.

6. The Troposphere

7. • This is the lowest layer of the atmosphere, closest to the
surface of the earth.
• The troposphere varies in height in different parts of the
world, from about 8km above sea level at the poles, to 16km
at the equator.
• Within the troposphere, the temperature drops rapidly the
higher you go.
• This is the layer where we see clouds and most of the
"weather" occurs.
• The top layer of the troposphere is called the tropopause.
• Within the troposphere the temperature drops to a low of -
56ºC. This marks the beginning of the tropopause.
• Through the tropopause, the temperature reverses and
begins to increase.
• The height of the tropopause varies from the poles to the
equator, but also from the summer to winter.

8. The Stratosphere

9. • For a distance of about 18km above the
tropopause, there is a layer called the stratosphere.
• In this layer, the pressure continues to decrease,
but the temperature increases gradually to 0ºC.
• Like the troposphere, the stratosphere also varies
in thickness.
• It is quite deep over the poles and thinner over the
equator.
• The stratosphere contains a layer of ozone which
absorbs the Sun's ultraviolet rays, protecting life on
the earth's surface.
• The top layer of the stratosphere is called the
stratopause. In this layer the temperature, once
again, begins to fall.

10. The Mesosphere

11. • The mesosphere reaches up to about 80km
above the surface of the earth.
• This is the coldest layer of the atmosphere,
where the temperature drops rapidly with
altitude.
• In the top layer of the mesosphere, called the
mesopause, the temperature bottoms out at a
low of about -100ºC at 80km above the earth.
• After that the temperature begins to rise again
with greater altitude.
• This is the layer where meteorites usually burn
up as they enter the atmosphere.

12. The Thermosphere

13. • The thermosphere extends upwards from a point
80-100 kilometres above the earth's surface.
• There is very little air in this layer.
• The temperature continues to rise in the
thermosphere and beyond, increasing for an
indefinite distance into space.

14. The Exosphere
• The exosphere is the very outer limit of the
atmosphere.
• The bottom of this layer is found at 500
kilometres above the Earth's surface.
• The pressure drops to little more than a
vacuum. Auroras form in the exosphere.
Auroras- उषा

15. Thank You