1. The 
Atmosphere

2. Atmospheric Layers- Quick Clip

6. Composition.... What makes up the atmosphere?
Does this surprise 
you?
Why?
Natural processes such as 
evaporation, condensation of water, photosynthesis, 
respiration, and decay are all involved in the use and renewal of gases. How?

7. Earth's Atmosphere has 5 major layers

9. These variations in air pressure cause the 
weather to change

10. Troposphere This is the layer just above the crust of the Earth.
It extends from 0 km to 16 km
Remember the football picture? It is closest to Earth, so it has the HIGHEST air pressure and is the densest.
All weather happens at this layer

11. Stratosphere This layer extends from 16 km- 50 km
Airplanes fly near the bottom of this layer
The ozone layer is located here

12. Ozone Layer What is Ozone?
The ozone is a layer of gas located in the stratosphere of our 
atmosphere.
It protects plants, animals, and us by blocking the most harmful rays of 
the sun.

13. Mesosphere This 3rd layer extends from 50km to 90 km
Meteors or shooting stars burn up at this layer
This is the coldest layer of the atmosphere
This is the hardest layer to study because planes cannot fly high 
enough but satellites cannot fly low enough.

14. Thermosphere This 4th layer extends from 90 km to 300 km
Shimmering light called auroras happen here
This is the hottest layer of the atmosphere
The space shuttle orbits at this layer

15. Exosphere This is the furthest layer from Earth
It extends from 300 km to more than 600 km
Many satellites orbit here
Air pressure is lowest here
It is sometimes considered part of outer space

16. But there's a problem...
This protective layer is
getting thinner and thinner.
It even has a hole in
it the size of
North America.
Why is this a problem?

17. How it all started
In the late 1920s, chemicals called chlorofluorocarbons (cloro-floro-carbons) or CFCs, were invented.
These chemicals were not poisonous and didn't harm fabrics, plants or people.
Companies thought they were great and used them in refrigerators, air conditioners, styrofoam packaging, and 
spray cans.
From the 1920s to the 1970s, billions of CFC molecules were released into the air.
In the 1970s, scientists began to wonder what might happen to all those CFCs after they had been in the air for
a while.
They eventually learned that CFCs could float past the troposphere up into the stratosphere where UV rays
would break them down. The chemicals that make up CFCs, mainly chlorine and fluorine, would float around
the stratosphere, breaking up ozone molecules. This was bad, because scientists knew that ozone in the stratosphere protects the Earth from too many UV rays.

18. Fixing the problem
In 1979, many countries, including the U.S., banned CFCs from 
being made or used. This was a big step toward fixing the problem. 
Today, no spray cans contain CFCs. Other chemicals are gradually 
replacing the CFCs in air conditioners.
But the CFCs already in the atmosphere can take up to 50 years to 
reach the stratosphere. Once there, they hang around in the 
stratosphere for many years, doing damage.
Also, the products that still contain CFCs need to be treated with 
care. One example of this is a car air conditioner. When the air 
conditioner breaks, or the car is taken to a junkyard, the CFCs need 
to be carefully taken out and recycled or stored so that they don't 
leak into the air.

19. 1. Try to use products which are labeled "Ozone-Friendly"
The future
Scientists originally predicted that the ozone layer would be the 
thinnest around 2008, then start recovering. But new research 
shows that other air pollution problems are slowing down the 
ozone layer's ability to rebound.
What you can do
1. Try to use products which are labeled "Ozone-Friendly"
2. People with cars should have their air conditioning unit 
checked regularly.
3. Recycle broken refrigerators and air conditioners.
4. Protect your skin and eyes from harmful UV rays when you're 
outside.

21. Pollution and Global Warming

22. What is 
pollution?
Generally any substance that 
people introduce into the 
atmosphere that has damaging 
effects on living things and the 
environment is considered air 
pollution.

23. What causes pollution? Sulfur Dioxide Carbon Dioxide
Smog, acid rain, volcanoes
Cars, planes, power plants, and other 
human activities that involve the 
burning of fossil fuels such as gasoline 
and natural gas.

24. Because there are more and more greenhouse gases in the atmosphere, more 
heat is trapped which makes the Earth warmer. This is known as GLOBAL 
WARMING.