Structure and Composition of the Atmosphere- Grade 10 Geography

1. COMPOSITION AND STRUCTURE
OF THE ATMOSPHERE
GEOGRAPHY GRADE 10
NA KAMENYE

2. INTRODUCTION
The atmosphere of the Earth is a layer of gases
surrounding the planet Earth.
The atmosphere protects life on Earth.
It becomes thinner and thinner with increasing
altitude, with no definite boundary between the
atmosphere and outer space

3. COMPOSITION OF THE
ATMOSPHERE
 The atmosphere is composed of a mixture of gases, solids
and liquids.
 Solids? Particles of dust and dirt that float around in the
air. Most of these particles are invisible to the human eye.

4. ATMOSPHERIC GASES
(Mixture of gases, solids and liquids)
 Nitrogen - 78%
 Oxygen - 21%
 Water Vapor - 0 to 4 %
- Used for clouds and precipitation
 Carbon dioxide – 0,37%
- Keeps the Earth warm and is used by plants to make food
 Argon – 0, 93%
 Traces of neon, helium, methane, krypton, xenon, hydrogen
and ozone

5. STRUCTURE OF THE ATMOSPHERE
THE ATMOSPHERE HAS FIVE (5) LAYERS

8. 1. TROPOSPHERE
The troposphere is the layer directly
above the earth’s surface.
It extends up from surface for 12 km. the
upper boundary of the layer is the
tropopause.
 It is warmed by the earth’s long-wave
radiation, and processes like conduction
and convection.
The temperature decreases with
increasing altitude at average rate of
6,4°c/1000 m. this is called the
environmental/normal lapse rate.
All weather processes take place in this
layer.
Air pressure falls with height.

9. 2. STRATOSPHERE
 The stratosphere layer extends in
altitude from 12-50 km. the upper
boundary of the layer is the stratopause.
 The ozone layer is situated between 15-
35 km above the ground and is called the
ozonosphere. ozone absorbs incoming
ultraviolet radiation, which may be
harmful to humans, other animals and
plants.
 The stratosphere is characterised by an
increase in temperature caused by a
concentration of ozone.
 Stratosphere is the layer of the
atmosphere where planes usually fly.
Most of the jet aircraft fly in the lower
layer of the stratosphere, to avoid any
turbulence.
 It acts as protective layer against
incoming meteorites.

10. WHAT IS OZONE?
 Ozone is a gaseous layer in the
stratosphere that protects the
earth from harmful ultraviolet
(UV) radiation.
 It is a molecule made up of three
oxygen atoms, often referenced as
O3.

11. 3. MESOSPHERE
The mesosphere layer extends
from 50-80 km.
 It receives meteoric dust, which
forms nuclei.
 Noctilucent clouds form from
ice crystals.
 Temperature falls rapidly, with
lowest temperatures of -90°c.
ice crystals form around nuclei.
 It is the coldest layer
 Strongest winds are recorded
 Meteors burn up due to friction

12. 4. THERMOSPHERE
 The thermosphere is the uppermost
layer of the atmosphere, from 80-480
km. uppermost boundary is the
thermopause.
 There is a rapid increase in temperature
with increase in height, to 1500°c.
 Solar radiation is absorbed by atomic
oxygen.

13. 5. EXOSPHERE
 The exosphere is the
outermost layer of the
atmosphere.
 The temperature in the
exosphere goes up with
altitude.
 Satellites orbit earth in the
exosphere.

15. References
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2022).
Horton, S. (2015). Atmosphere. Available from Slideshare at https://www.slideshare.net/snshnecu/atmosphere-
43466985 (Accessed 20 August 2022).
Mas, P.B. (2013). Earth’s Atmosphere. Available from Slideshare at
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Roberts, C. (2008). Layers of the Atmosphere. Available from Slideshare at
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362500d52bf3&v=&b=&from_search=1 (Accessed 20 August 2022).
Volante, P.D. (2012). The layers of the Atmosphere. Available from Slideshare at
https://www.slideshare.net/patriciadanisevolante/the-layers-of-the-atmosphere-15014826 (Accessed 20 August
2022).