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Today’s Objective: What Features Allow Earth To Support Life?
Do Now – Pick up and complete Worksheet

2. Life and the Atmosphere
**Review **
Life and the Atmosphere
The Earth’s original atmosphere was made up of gases similar to those released in volcanic eruptions – water vapor, carbon dioxide & nitrogen.
Later, primitive organisms evolved that used photosynthesis and released oxygen.

3. Composition of Atmosphere
Nitrogen and Oxygen gases make up 99%.
Gases in the atmosphere today: Page 1 ESRT

4. What features does Earth have that allow it to support life?
Abundant usable water.
Suitable atmosphere.
Suitable range of
temperatures.

5. What determines the temperature of a planet?
Distance from the sun.
Presence and composition of the atmosphere.

6. Other Parts of the Atmosphere
Water Vapor:
- source of all clouds and
precipitation.
- absorbs heat (from earth & sun)
Dust Particles:
- sea salt
- soil
- ash from volcanic eruptions

7. Ozone:
- form of oxygen that combines three oxygen atoms into each molecule (O3).

8. What do you think could happen if there was no ozone?
- If ozone did not filter most UV radiation and all of the sun’s UV rays reached the surface of Earth, our planet would be uninhabitable for many living organisms.

9. Human Influence on the Atmosphere:
- Emissions from cars and factories account for nearly half the primary pollutants by weight.

10. What changes can “we” make to help our atmosphere?
Use buses and trains instead of cars
Walking or cycling
Car pool
Use less electricity