1. Our Security Blanket

2.  1. Gases surrounding the planet held there by gravity.  2. Protects life by absorbing ultraviolet radiation.  3. Reduces temperature extremes between day and night.

3. 4. Heats the surface during the day. 5. Mass is about 5.0 x 1018 kg 6. Line between out space and atmosphere is about 120 km where space shuttle begins to experience atmospheric effects 7. Average Temperature at Earth’s surface - 14C (57F)

4. 78% nitrogen 2. 21% oxygen 3. 0.93% argon 4. 0.038% carbon dioxide

5. 1. Water vapor 2. Methane and nitrous oxide 3. Ozone 4. Carbon dioxide

6. 1. Dust 2. Pollen 3. Sea spray 4. Spores

7. 5. volcanic ash 6. meteoroids 7. fluorine. mercury, sulfur (industry pollutants)

8. Exosphere a. Composed of hydrogen and helium b. So thin, particles travel 100’s of km to collide with another c. Does not act like a fluid anymore

9. Thermosphere (Ionosphere) a. 250 to 800 km above Earth b. Temperature rises with height to 1500 C c. Space Station is located in the thermosphere. d. Contains the ionosphere (over laps into the exosphere) Aurora Borealis occur here

10. Mesosphere a. 80 to 85 km b. Temperature decreases with height c. Top of the mesosphere is -100C-coldest place on Earth

11. Stratosphere a. 50 to 60 km b. Temperature increase with height c. Pressure is 1/1000th that at sea level d. Contains ozone layer which protects us from ultraviolet  radiation

12. Troposphere a. From Earth’s surface to17 km b. Heated by heat transfer from the surface-vertical mixing c. Weather occurs here d. Planes travel in upper part