1. Today’s Agenda… Bellringer: Based on your scavenger hunt worksheet – what do you think the new unit will be about? Brainstorm as many topics as possible. Take up corrections Notes on Earth’s Atmosphere

2. Think about it!??! Why can we live on Earth, but not on the moon? Why do astronauts have to wear space suits and helmets on the moon? What causes Earth to have air and not the moon?

3. Earth’s Atmosphere Study Pack #2

4. Today’s Goals… I can describe the layers of the Earth’s atmosphere.

5. Atmosphere Thin layer of air that forms a protective covering around the planet What would happen if Earth did not have an atmosphere? – Maintains a balance of heat on Earth – Protects life forms from the sun’s harmful rays

6. What is it made of? Mixture of gases, solids, liquids Nitrogen is the most abundant gas Oxygen, argon, carbon dioxide

7. The Atmospheric Layers Layers: – Troposphere – Stratosphere – Mesosphere – Thermosphere – Exosphere

8. Troposphere Lowest layer We live here Extends up 10 km Weather and clouds are here

9. Stratosphere 10 – 50 km up Contains the ozone layer – Shields you from the sun’s harmful UV rays

10. Mesosphere 50 – 85 km You may see shooting stars here

11. Thermosphere 85 – 500 km Has very high temperatures

12. Ionosphere In the mesosphere and thermosphere is the ionosphere A layer of electrically charged particles Allows AM radio waves to travel across the country

13. Exosphere Space shuttles orbit here There is no clear line between this layer and space

14. Atmospheric Pressure Atmospheric gases reach hundreds of kilometers above Earth’s surface The force of gravity pulls gases down which causes them to press down on the gases below Air pressure is greater near Earth’s surface and it decreases higher in the atmosphere

15. Atmospheric Pressure Why is it difficult to breath as you go higher into the atmosphere? – The air is less dense (less pressure) – There are fewer molecules of air

16. Temperature in the Atmosphere The layers of the atmosphere are mostly based on differences in temperature Let’s find out how! Look at the diagram on page 344!

17. Temperature in the Atmosphere