The slides are about atmosphere

2. PRE-ACTIVITY

3. 1. What is atmosphere?
2. Name the three main gases found in the
atmosphere.
3. Do you think life can exist without the
atmosphere? WHY?

4. LESSON OBJECTIVES
AT THE END OF THIS LESSON, LEARNERS SHOULD BE ABLE TO:
Define atmosphere.
List all the gases that make up the atmosphere as well as their percentages.
Name the main layers of the atmosphere.
Discuss the importance of the atmosphere in our real life (living organisms and non-living
organisms).

5. WHAT IS THE ATMOSPHERE?
The atmosphere is the layer of gases which surrounds the earth.
It consist of the following mixtures:
 Nitrogen
 Oxygen
 Argon
 Carbon dioxide and other trace gases

6. COMPOSITION OF THE ATMOSPHERE

7. CONTINUED...
 Due to the Earth's rotation, the atmosphere is thicker at the equator than at the
poles.
On average it is about 12 km thick.
The atmosphere is actually a very thin layer compared to the size of the Earth.
It is almost like the skin of an orange, relative to the size of the orange.

8. THE LAYERS OF THE ATMOSPHERE
The atmosphere has four main layers.
MNEMONIC DEVICE: The Smart Man Takes the Elevator
Troposphere
Stratosphere
Mesosphere
Thermosphere
Exosphere

9. Above the thermosphere, the
atmosphere merges with outer
space in the layer known as the
exosphere

10. 1. THE TROPOSPHERE
The troposphere is the lowest
layer in the atmosphere.
It stretches from sea level up to about 9 km
at the poles and 17 km at the equator.
It is the lowest and most dense portion of the Earth's atmosphere above the Earth's
surface
The troposphere is orange in color.

11. CONTINUED…
The bottom part of the troposphere has a high enough density for us to breathe
and is the layer of the atmosphere in which we live.
The temperature in the troposphere decreases with altitude
The temperature decreases about 6,4°C for every kilometer increase in altitude.

12. 2. THE STRATOSPHERE
The stratosphere is the layer above the troposphere.
It stretches from 12 km to 50 km above the Earth’s surface.
The air is much more stable here than in the troposphere.
The density of the air in the stratosphere is very low and decreases with altitude.
 This layer consist of the Ozone gas (O3).

13. IMPORTANCE OF OZONE
 Absorbs harmful Ultraviolent rays (UV) from the Sun by forming, breaking down
and reforming ozone molecules over and over again.
When UV light reaches the Earth, it can cause cancer, affect plant growth, and the
life cycles of species.

14. 3. THE MESOSPHERE
The mesosphere extends from around 50 km to 80 km above the Earth's surface.
The atmosphere reaches its lowest temperature (-90 °C) in the mesosphere.
The air density is extremely low, but there is still enough air to burn up rocks and
dust entering from space.

15. 4. THE THERMOSPHERE
 The thermosphere is the layer of the atmosphere from 80 km upwards.
 The density of the air is extremely low.
 The further away you move from the Earth, the less dense the concentration of molecules
becomes until the atmosphere becomes space.
 Most satellites that we depend on every day are in Low Earth Orbit (LEO), orbiting the Earth at
an altitude between 160 km and 2,000 km.
 The International Space Station (ISS) is situated at 370 km in the thermosphere. This is an
international facility in space that is used for research purposes.

16. THE IMPORATNCE OF THE ATMOSPHERE
Provides the necessary gases for living things to survive.
Regulates the heat from the sun to just the right temperature for life on earth.
Plays an important role in the water cycle.
The ozone layer protects the earth from the sun’s harmful UV rays.
Protect the Earth from small meteors.

17. SUMMARY

18. ACTIVITY 12 AUGUST 2022