•Pressure is only ~1% of Earth’s
•Composition:
95% CO2 3% N2
2% Ar
•
•Water:
–Pressure
too low for liquid water to exist
•Boiling
point drops with pressure
•Freezing
point doesn’t change much with pressure
•Eventually
boiling point reaches freezing point
•Water
goes directly from solid phase to gas phase
•CO2 (dry ice) is like this even at
terrestrial atmospheric pressure
–Water
seen in atmosphere
–Water
seen in polar caps
–Evidence
of running water in past
•Carbon
dioxide (CO2)
–Gets
cold enough for even this to freeze at polar caps
–Unusual
meteorology, as atmosphere moves from one pole to other each “year”