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Positive and negative feedback in climate change
It can all get pretty complicated
CLOUD EXAMPLE …
1 more thing …. (giving back test took up so much time)
IR Greenhouse effectpositive feedback
Back-Scattered
reflected
VIS
Albedo effectnegative feedback
sunlight
HEATING
COOLING
H20
reflected
VIS
Albedo effectnegative feedback
sunlight
HEATING
H20
More H2O More clouds
More sunlightreflected
T decreasesLess H2O
Less heating
IR Greenhouse effectpositive feedback
Back-Scattered
COOLING
H20
More H2OMore clouds
Less IR Transmitted
T increases More H2O
Less cooling
More clouds
More sunlightreflected
T decreasesLess H2O
Less heating
More H2O
More clouds
Less IR Transmitted
T increases More H2O
Less cooling
Both processes together
Who’s gonna win?
The Jovian planets
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?
Accretion of planetesimals (now mostly icy)Recall how a Jovian planet developed ….
Ices more abundant… Planetesimals can form that are much more massive than the terrestrials
Accretion disk
At some point the planetesimal becomes massive enough to start capturing H and He gas!
As gas becomes captured, planet’s mass increases further…
More gas is attracted and captured, so that the process accelerates …
More gas is attracted and captured, so that the process accelerates …
This continues until the background gas supply is exhausted
Massive solar wind from young sun removes background gas
Ice, rocks and
metals
H and He
The finished product …
(failed sun)
Why the mass differences ….Protoplanetary disk
density
Protosun
Frost line
Why the mass differences ….
Jupiter
Saturn
Uranus
Neptune
Further out you are …• Density of material less• Stuff moves slower
Proto-planets grow faster the closer in they
are
Why the mass differences ….
Jupiter
Saturn
Uranus
Neptune
Sun ignites
Slow growers
Why the mass differences ….
Jupiter
Saturn
Uranus
Neptune
Young solar wind scours away the dust
and gas
Stuck with what they
had acquired so far
Neptune Uranus Less H and He …. Higher densities 1.67 g/cc
1.24 g/cc
Inw
ard
Less
den
se?
Neptune Uranus Less H and He …. Higher densities 1.67 g/cc
1.24 g/cc
Saturn Jupiter Lots of H and He …. low densities
0.71 g/cc1.33 g/cc
Inw
ard
Less
den
se?
?
Gasses are a lot more compressible than solids
Increase in mass, more compression
water
Strong magnetic fields due to fast rotation and huge metallic H cores
magnetic fields due to ?
Like terrestrial mag fields
Fields pretty well-correlated with rotation axis
Not at allLocalized
phenomena?
Appearances ?
0.4 days! 0.7 days!
Rotation periods fast (from large contractions?)
Global weather patterns
Rotation + convection global weather belts
Jupiter’s belts
Jupiter’s colors
(Saturn’s clouds are similar, but lie deeper in its atmosphere)
Uranus and Neptune’s colors
ALL those MOONS !
As of march 2015:
Jupiter 67Saturn 62Uranus 27Neptune 14Pluto 5
Galileo saw four moons thru his little telescope
The “Galilean moons”
Jupiter’s known moons
Pink – Galilean moons
Saturn’s known moons
The Galilean moons of Jupiter
Io
Most volcanically active world in solar systemWhere does the heat come from?
Yellow: Sulfur deposits
Synchronous orbit (1.8 days)
Tidal Heating
Eccentric orbit a consequence of orbital resonance
