2. The Atmosphere
ICS 3

3. California State Standards
Earth Science 8a.
Students know the thermal structure and chemical composition of the atmosphere

4. Composition of the Atmosphere1%
<1%
<1%
21%
78%

5. Layers of the
Atmosphere

6. Layers of the Atmosphere
- Earth’s atmosphere is divided into 4 layers, according to the temperature gradient.

7. Altitude
Temperature

8. Layers of the Atmosphere
Troposphere
- Weather occurs and life exists here
The tropopause begins at approximately 10 meters above the surface of the earth and ends at about 20 meters. This is where the temperature does not change.

9. Layers of the Atmosphere
Stratosphere
- Similar composition to troposphere
but without water.
-The stratopause begins at about 45 and ends at approx. 53 meters.
Contains ozone (O3) layer which
absorbs harmful ultraviolet
radiation from the sun

10. Layers of the Atmosphere
Mesosphere
- Air has very low density and is the coldest layer.
- The Mesopause is more than 80 kilometers above the surface and temperatures approach -90 degrees Celcius .

11. Layers of the Atmosphere
Thermosphere
- Has very few air molecules which
receive direct rays from the sun
- Has a high temperature because it is heated by the Sun. The space shuttle orbits in the middle to upper part of this layer. The Aurora Borealis occurs in this layer.

12. California State Standards
Earth Science 8c.
Students know the location, role, and properties of the ozone layer

13. The Ozone Layer oxygen we breathe is diatomic (O2)
ozone is a triatomic molecule (03)

14. The Ozone Layer Ozone forms in the stratosphere
Ozone absorbs harmful ultraviolet radiation from the sun

15. The Ozone Layer
(UV radiation) + 3O2  2O3

16. The Ozone Layer
and
Humans

17. catalyst: something that speeds up a chemical reaction
The Ozone Layer
and Humans
certain chemicals humans put in the air act as catalysts in breaking up ozone molecules
catalyst: something that speeds up a chemical reaction

18. The Ozone Layer these catalysts are called chlorofluorocarbons (CFC’s)
and Humans
these catalysts are called chlorofluorocarbons (CFC’s)
a few CFC molecules can destroy hundreds of ozone molecules

19. California State Standards
Earth Science 4c.
Students understand the mechanism and significance of the greenhouse effect.

20. The Greenhouse Effect

21. The Greenhouse Effect
greenhouse gases trap energy from the sun inside Earth’s atmosphere
carbon dioxide (CO2)
water vapor (H2O)
methane (CH4)
CFC’s and other pollutants

22. Greenhouse gasses

23. California State Standards
Earth Science 8b.
Students know how Earth’s atmosphere evolved over time

24. Evolution of
the
Atmosphere

25. Earth was formed by inelastic collisions
Evolution of the Atmosphere
Earth was formed by inelastic collisions
volcanic eruptions (outgassing) and bombardment of material from comets and asteroids formed the early atmosphere

26. Evolution of the Atmospheregg

31. Evolution of the Atmosphere
Chemical reactions through time, in the presence of water, changed the methane (CH4) and ammonia (NH3) into nitrogen (N2), hydrogen (H2), and carbon dioxide (CO2)

32. Evolution of the Atmosphere
Hydrogen (H2) escaped because it’s lightweight, leaving mostly nitrogen (N2).

33. Evolution of the Atmosphere
photosynthetic bacteria evolved and converted carbon dioxide (CO2) into oxygen (O2)

34. Evolution of the Atmosphere
levels of gases in the atmosphere have been stable for the past 600 million years