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 …

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

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

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

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?

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?

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

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!

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

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

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

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

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

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

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

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

Increase in mass, more compression

water

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

Fields pretty well-correlated with rotation axis Not at all Localized 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 67 Saturn 62 Uranus 27 Neptune 14 Pluto 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 system Yellow: Sulfur deposits Most volcanically active world in solar system Where does the heat come from?

Tidal Heating Synchronous orbit (1.8 days)

Eccentric orbit a consequence of orbital resonance