1. Gases in Atmospheres Volatiles in Molecular Form (ice or gas): –Carbon dioxide CO 2 (molecular weight = 44) –Oxygen O 2 (molecular weight = 32) –Nitrogen N 2 (molecular weight = 28) –Water H 2 O (molecular weight = 18) Other gases: –Argon Ar (molecular weight = 40) –Neon Ne (molecular weight = 20) Jovian gases: –Ammonia NH 3 (17), Methane CH 4 (16), Helium He (4), and Hydrogen H 2 (2)

3. Light and Atmospheres Greenhouse gases absorb infrared light Scattering of visible wavelengths depends on wavelength Molecular dissociation by ultraviolet light Ionization by X-rays

4. Atmospheric Layers

5. Greenhouse Effect

6. Blue Sky: Scattered Light

7. UV and X-ray Light Ozone (O 3 ) in stratosphere of Earth absorbs ultraviolet light. –Chemical balance between O 3 and O 2 –Chlorofluorocarbons (CFCs) destroy ozone X-rays ionize the upper layers of the atmosphere (ionosphere) –Charged particles reflect low frequency radio waves (e.g., AM radio)

8. Temperature Profiles

9. Magnetosphere

10. Convection

11. Convection on Earth

12. Wind Patterns on Earth

13. Water Cycle on Earth

14. Creation of Terrestrial Atmosphere

15. Loss of Atmosphere

16. Thermal Escape of Gas

17. Retaining an Atmosphere Gas will have a lifetime of several billion years if the escape velocity is 10 times the rms velocity

19. Become Aware of Greenhouse Effect!