atmospheric pressures
- From: mrdarrett@xxxxxxxxx
- Date: 27 Jun 2006 16:31:08 -0700
I was wondering what the minimum diameter of Earth would have to be in
order to provide atmospheric pressure for water to remain liquid at
observable ambient temperatures.
I dusted off my thermodynamics book, and I noticed that at say 40 C
(about the upper limit of ambient temperature, excluding deserts,
etc.), the vapor pressure of water is about 7 kPa. So, if we let water
boil at 40 C on a hypothetical Earth, the minimum atmospheric pressure
required is 7 kPa.
Looking on wikipedia, I notice that Mars has a diameter of about 6800
km (0.533 of Earth's) and a mass of 0.107 of Earth's. Martian
atmospheric pressure is about 0.8 kPa.
Then I looked up Titan, and noticed that Titan's diameter is 5,150 km
(0.404 of Earth), and has a mass of 0.0225 of Earth's. But wait a
minute, it has a nitrogen atmosphere of 147 kPa!
So I'm guessing now that atmospheric pressure isn't solely dependent on
a body's mass or diameter, but is more heavily dependent on how much
gaseous material is available...?
Any thoughts on this...?
.
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