1. Positive and negative feedback in climate change
1 more thing …. (giving back test took up so much time)
Positive and negative feedback in climate change
It can all get pretty complicated
CLOUD EXAMPLE …

2. COOLING H20 HEATING IR VIS sunlight reflected Albedo effect
negative feedback
COOLING
H20
Greenhouse effect
positive feedback IR
HEATING
VIS
Back-Scattered

3. H20 HEATING VIS sunlight reflected More H2O More clouds Albedo effect
negative feedback
More sunlight
reflected
Less heating
H20
Less H2O
T decreases
HEATING
VIS

4. COOLING H20 IR More clouds More H2O Less IR Transmitted Less cooling
T increases
More H2O
Greenhouse effect
positive feedback IR
Back-Scattered

5. Both processes together
More H2O
More clouds
More clouds
Less IR
Transmitted
More sunlight
reflected
Less cooling
Less heating
T increases
More H2O
Less H2O
T decreases
Who’s gonna win?

6. The Jovian planets

7. Gas giants
“Ice giants”
All formed beyond the frost line …
Q1: Why are Uranus and Neptune smaller?
Q2: Why is Jupiter twice as dense as Saturn?

8. Recall how a Jovian planet developed ….
Accretion of planetesimals (now mostly icy)

9. Planetesimals can form that are much more massive than the terrestrials
Ices more abundant…
Accretion disk
At some point the planetesimal becomes massive enough to start capturing H and He gas!

10. As gas becomes captured, planet’s mass increases further…

11. More gas is attracted and captured, so that the process accelerates …

12. More gas is attracted and captured, so that the process accelerates …

13. This continues until the background gas supply is exhausted
Massive solar wind from young sun removes background gas

14. The finished product …
H and He
Ice, rocks and metals
(failed sun)

15. Protoplanetary disk density
Why the mass differences ….
Protoplanetary disk density
Protosun
Frost line

16. Proto-planets grow faster the closer in they are
Further out you are …
Density of material less
Stuff moves slower
Why the mass differences ….
Proto-planets grow faster the closer in they are
Neptune
Saturn
Jupiter
Uranus

17. Why the mass differences ….
Sun ignites
Neptune
Saturn
Jupiter
Slow growers
Uranus

18. Why the mass differences ….
Young solar wind scours away the dust and gas
Neptune
Saturn
Jupiter
Stuck with what they had acquired so far
Uranus

19. Neptune
Uranus
1.67 g/cc
1.24 g/cc
Less H and He …. Higher densities
Inward
Less dense?

20. Neptune
Uranus
1.67 g/cc
1.24 g/cc
Less H and He …. Higher densities
Inward
Less dense?
Saturn
Jupiter
0.71 g/cc
1.33 g/cc
Lots of H and He …. low densities ?
Gasses are a lot more compressible than solids

21. Increase in mass, more compression

22. water

23. Strong magnetic fields due to fast rotation and huge metallic H cores
Like terrestrial mag fields

24. Fields pretty well-correlated with rotation axis
Not at all
Localized
phenomena?

25. Appearances ?
0.4 days!
0.7 days!
Rotation periods fast (from large contractions?)

26. Global weather patterns
Rotation + convection  global weather belts

27. Jupiter’s belts

28. Jupiter’s colors
(Saturn’s clouds are similar, but lie deeper in its atmosphere)

29. Uranus and Neptune’s colors

30. ALL those MOONS ! As of march 2015: Jupiter 67 Saturn 62 Uranus 27
Neptune 14
Pluto 5

31. Galileo saw four moons thru his little telescope
The “Galilean moons”

32. Jupiter’s known moons
Pink – Galilean moons

33. Saturn’s known moons

35. The Galilean moons of Jupiter

36. Io Most volcanically active world in solar system
Yellow: Sulfur deposits
Most volcanically active world in solar system
Where does the heat come from?

37. Tidal Heating
Synchronous orbit (1.8 days)

38. Eccentric orbit a consequence of orbital resonance