1. Charles Hakes Fort Lewis College1

2. Charles Hakes Fort Lewis College2 Blackbodies Atmospheres

3. Charles Hakes Fort Lewis College3 Outline Review Kinetic Energy/Temperature Blackbodies Atmospheres Green House Effect

4. Charles Hakes Fort Lewis College4 Tutor (Shane) l Thursday 5-6 (or longer if needed) BH640 l Register clickers… l Homework…

5. Charles Hakes Fort Lewis College5 Review What was the most important thing you learned? There are charged particles bouncing back and forth on the (field lines in the) magnetosphere Aurora… “excited” molecules (or atoms) being “bumped” in the atmosphere Temperature is a measure of the average kinetic energy of a body’s molecules. E k = 1 / 2 Mv 2

6. Charles Hakes Fort Lewis College6 Review What was the most important thing you learned? The solar wind is NOT the only reason Mars has no atmosphere. The magnetosphere of Jupiter is the largest object in the solar system.

7. Charles Hakes Fort Lewis College7 Tornado

8. Charles Hakes Fort Lewis College8 Tornado Tornado photo courtesy of Gary Gianniny and email from Scott White.

9. Charles Hakes Fort Lewis College9 Which temperature will freeze water? A) 65° F B) 5° C C) 263 K

10. Charles Hakes Fort Lewis College10 Temperature Temperature is just a measure of the average kinetic energy of a body’s molecules. Go to Solar System Collaboratory to see temperature scales.Solar System Collaboratory

11. Charles Hakes Fort Lewis College11 More Precisely 2-1 The Kelvin Temperature Scale

12. Charles Hakes Fort Lewis College12 Temperature With enough kinetic energy (temperature), molecules can “escape” from a planet. http://www.xkcd.com/681/

13. Charles Hakes Fort Lewis College13 Small Group Exercise Normal Human body temperature is 37 ° C. What is this temperature in Kelvins?

14. Charles Hakes Fort Lewis College14 Heat Transfer Conduction Transfer from one mass to another mass that is touching. Convection Transfer though a gas (air) that moves across a mass Radiation Transfer using electromagnetic radiation This is the least efficient method This is the only method available in/through space

15. Charles Hakes Fort Lewis College15 Albedo Albedo - the fraction of light that is reflected from a planet (or other solar system body). A unitless number from 0 to 1. 0 - all light is absorbed (very black) 1 - all light is reflected (very white) Earth's average albedo is 0.30, so 30% of the sunlight is reflected. The light absorbed would be one minus the albedo. For the Earth, 1.00-0.30=0.70, so 70% of the light is absorbed.

16. Charles Hakes Fort Lewis College16 Blackbody Radiation “Blackbodies” are not black. Blackbody Radiation is from an “ideal” object with albedo = 0. Any dense, warm, object can be approximated as a “blackbody”. The “peak” of the radiation “curve” is related to the temperature of the radiator.

17. Charles Hakes Fort Lewis College17 Figure 2.9 Ideal Blackbody Curve

18. Charles Hakes Fort Lewis College18 Radiation Higher temperature bodies radiate energy in shorter wavelength radiation. The Sun radiates at visible wavelengths The Earth (and other planets) radiate at much longer wavelengths. Go to Solar System Collaboratory to see black body page.Solar System Collaboratory

19. Charles Hakes Fort Lewis College19 Figure 2.10 Blackbody Curves Note the logarithmic temperature scale. For linear scale, go look at the “black body” section of: http://solarsystem.colora do.edu/ http://solarsystem.colora do.edu/ example - oven

20. Charles Hakes Fort Lewis College20 Wein ’ s Law The “peak” frequency of the radiation “curve” is directly proportional to the temperature of the radiator.

21. Charles Hakes Fort Lewis College21 Small Group Exercise Normal Human body temperature is 37 ° C. What is this temperature in Kelvins? What is the peak wavelength emitted by a person at this temperature?

22. Charles Hakes Fort Lewis College22 Figure 2.8 Electromagnetic Spectrum

23. Charles Hakes Fort Lewis College23 What is the peak wavelength emitted by an object with temperature 6,000 K? A) 4.8x10 -5 cm B) 4.8x10 -4 cm C) 2.9x10 -5 cm D) 2.9x10 -4 cm

24. Charles Hakes Fort Lewis College24 Planet Temperature Go to Solar System Collaboratory on EVM “physics” page.Solar System Collaboratory A planet must balance absorbed light and radiated light to get a temperature. Light intensity decreases with distance. (another 1 /r 2 law) Farther from the sun, the absorbed light is less.

25. Charles Hakes Fort Lewis College25 Planet Temperature Go to Solar System Collaboratory on EVM “physics” page.Solar System Collaboratory A planet must balance absorbed light and radiated light to get a temperature. Light intensity decreases with distance. (another 1 /r 2 law) Farther from the sun, the absorbed light is less. Go to Solar System Collaboratory on planet temperature page.Solar System Collaboratory

26. Charles Hakes Fort Lewis College26 Figure 5.7 About 30% of the sunlight hitting the Earth is reflected

27. Charles Hakes Fort Lewis College27 To Atmosphere or Not Once you know a planet’s temperature you can see if it will have an atmosphere, and how that atmosphere can affect a planet’s temperature. Compare kinetic energy of molecules with “escape velocity” from the planet. Light molecules (of a given temperature T) move faster than heavy molecules of the same temperature. A small fraction will always escape.

28. Charles Hakes Fort Lewis College28 To Atmosphere or Not Primary atmosphere What a planet had after formation Mostly H, He - almost all gone from the terrestrial planets (never really was here) Secondary atmosphere Heavier molecules N 2, CO 2 From rock outgassing H 2 O from outgassing and comet impacts. O 2 from Life

29. Charles Hakes Fort Lewis College29 Earth’s Atmosphere 78% nitrogen 21% oxygen - this is from living organisms Plus Ar, CO 2, H 2 O. Note layers

30. Charles Hakes Fort Lewis College30 Figure 5.5 Earth ’ s Atmosphere

31. Charles Hakes Fort Lewis College31 Meteorology Science dealing with phenomena in the atmosphere (Not the study of meteors) Warm air rises and expands Cold air sinks and shrinks Must conserve linear and angular momentum.

32. Charles Hakes Fort Lewis College32 Figure 5.6 Convection

33. Charles Hakes Fort Lewis College33 Removing all greenhouse gasses from the Earth’s atmosphere would be good A) True B) False

34. Charles Hakes Fort Lewis College34 Three Minute Paper Write 1-3 sentences. What was the most important thing you learned today? What questions do you still have about today’s topics?