1. Chapter 3 Atmospheric Radiative Transfer and Climate To date, we have learned 1)The greenhouse effects, through understanding the simplest greenhouse model, 2)The aerosols effects on radiation, clouds, and temperature, 3)The global energy balance, that shows how global energy components are budgeted at the TOA, in the atmosphere, and at the surface. Now, we will further learn here 1)How greenhouse gases affect radiation, 2)How clouds influence radiation, 3)How they together impact temperature profiles, and 4)What is cloud radiative forcing?

2. Recap of the greenhouse effect Long-wave radiation 236 Wm -2 Equivalent T = 255 K (-18ºC) 390 Wm -2 T = 288 K (+15ºC) 236 Wm -2 Solar radiation Do you know where is this 236 coming from?

3. How greenhouse gases affect radiation?

4. How does the atmosphere affect radiation?

5. Atmospheric Absorption Solar radiation passes rather freely through earth's atmosphere. Earth's re-emitted longwave energy either fits through a narrow window or is absorbed by greenhouse gases and re-radiated toward earth. Wavelength Absorption (100%) Nitrous Oxide Methane Ozone Water Vapor Carbon Dioxide Total Atmo IR UV

6. Through this atmospheric “window”, satellite sensors are designed to “see”, observe, measure or monitor the Earth’s surface. Spectra of outgoing radiation from Earth observed by IRIS on Nimbus 3

7. What are the dominant gases in the atmosphere? Diatomic molecules like N2 and O2 have no permanent dipole moment and no bending moment and so have no capacity to absorb or emit low energy thermal radiation. N2 and O2 Are they greenhouse gases? Why not? What are greenhouse gases? CO2, N2O,H2O, O3

8. Nuclear Configuration and Permanent Dipole Movement Symmetric, linear molecules (Both ends look the same) Nonlinear or bent Have pure rotation bands

9. Vibrational Modes of Diatomic and Triatomic Molecules

10. How do greenhouse gases affect the temperature profile? (1/2)

11. How do greenhouse gases affect the temperature profile? (2/2)

12. Thermal equilibrium profiles

13. How do clouds affect radiation? 1. Liquid water path and solar zenith angle

14. How do clouds affect radiation? 2. Cloud particle size

15. How do clouds affect radiation? 3. Cloud phase (water versus ice)

16. How do clouds affect the temperature profile?

17. How do clouds affect net radiation at TOA?

18. How do clouds affect shortwave radiation? Cloud forcing = average ( or cloudy) – cloud-free

19. How do clouds affect longwave radiation? Cloud forcing = cloudy – cloud-free

20. How do clouds affect net radiation? Cloud forcing = cloudy – cloud-free NET = SW + LW

21. How do clouds distribute globally?

22. How are clouds measured from space?

23. High clouds measured from space?

24. Low clouds measured from space?

25. Summary Now, we have learned: 1)How greenhouse gases affect radiation, 2)How clouds influence radiation, 3)How they together impact temperature profiles, and 4)What cloud radiative forcing is.

26. Seasonal patterns of shortwave cloud radiation

27. Seasonal patterns of longwave cloud radiation

28. Seasonal patterns of net radiation cloud forcing