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Thread: Vacuum,pressure, and greenhouse effect

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    Vacuum,pressure, and greenhouse effect

    What is the highest vacuum in;
    1.Space.
    2.Achievable by humans with present technology.
    ?

    And;
    What is the highest pressure that atmosphere of the terrestrial/jovian planet can have?
    What is the highest greenhouse effect imaginable in the atmosphere of the terrestrial planet?

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    Quote Originally Posted by m1omg View Post
    What is the highest vacuum in;
    1.Space.
    I'm sure there is some more to this statement.
    Quote Originally Posted by m1omg View Post
    2.Achievable by humans with present technology.
    ?
    In our ground level atmospheric pressure? Or can we go into space?

    Yes; I know I'm being obstinant, but it sounds like you're leading somewhere, and you piqued my curiosity.

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    Quote Originally Posted by NEOWatcher View Post
    I'm sure there is some more to this statement.

    In our ground level atmospheric pressure? Or can we go into space?

    Yes; I know I'm being obstinant, but it sounds like you're leading somewhere, and you piqued my curiosity.
    1.In outer space.
    2.Both in space and in our atm. pressure.
    And I am not leading anywhere, just being curious.
    Last edited by m1omg; 2007-Jun-26 at 05:47 PM.

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    Quote Originally Posted by m1omg View Post
    What is the highest greenhouse effect imaginable in the atmosphere of the terrestrial planet?
    A terrestrial planet has an undetermined upper limit to its size -- any larger and it would have retained hydrogen and helium in its formation and become a gas giant.

    This means there is an upper limit to the temperature of atmospheric gases it can retain before they become so energetic that they escape the planet's gravitational pull.

    If temperature increases with pressure, as on Venus, then maybe you can estimate the maximum atmospheric pressure on a terrestrial planet.

    By this reasoning, it would be a much greater pressure than that found on Venus, since terrestrial planets can be much more massive and the temperature of Venus' atmosphere is nowhere near the escape velocity for CO2.

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    Quote Originally Posted by m1omg View Post
    What is the highest vacuum in;
    1.Space.
    2.Achievable by humans with present technology.
    By highest vacuum, I assume you mean lowest pressure. The answer is not zero, there is always something there.

    There is some information here about pressures in space, but it looks like values of from around 10^-11 to 10^-18 Pa. This wikipedia article has more.

    With well designed and run ultra high vacuum systems, 10^-9 is certainly achievable. Reference 15 in this wikipedia article on vacuum mentions 10^-13 torr, which is 10^-10 Pa.
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    Quote Originally Posted by Swift View Post
    By highest vacuum, I assume you mean lowest pressure. The answer is not zero, there is always something there.

    There is some information here about pressures in space, but it looks like values of from around 10^-11 to 10^-18 Pa. This wikipedia article has more.

    With well designed and run ultra high vacuum systems, 10^-9 is certainly achievable. Reference 15 in this wikipedia article on vacuum mentions 10^-13 torr, which is 10^-10 Pa.
    Thanks.

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    In many hours of pumping and at great expence, a million liter laboritory vacuum can have fewer than 1000 particles bouncing around inside. We can't do much better as the walls of the container release another particle once per hour to much oftener, even if the container is much smaller.
    It is thought that the space between galaxies is sometimes this good a vacuum. In our solar system the vacuum is much inferior, mostly because of the solar wind from our Sun.
    My guess is a planet of 1000 Earth mass with one million times Earth's sea level air pressure can be 1000 degrees c = 1832 degrees f if there is a high percentage of green house gas and vapor in the outer atmosphere. That is assuming the temperature with no atmosphere would be -39 degrees c = -39 degrees f. Less massive planets with much less atmosphere will only warm about 100 degrees c = 212 f above a no atmosphere temperature of -39 c =-39 f. In all cases, we are neglecting heat from the interior of the planet, which is typically unimportant, but could heat the surface greatly. Neil

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    1000 Earth masses for a terrestrial planet?You gotta kidding me!
    And Venus has lower mass than Earth and 90 bars of co2 pressure and it is 500 degress hot, why 1 mil. atm?I estimate that 180 bar atmosphere of co2 will heat surface to 1000 degress.
    Last edited by m1omg; 2007-Jun-30 at 01:43 PM.

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    Quote Originally Posted by neilzero View Post
    In many hours of pumping and at great expence, a million liter laboritory vacuum can have fewer than 1000 particles bouncing around inside. We can't do much better as the walls of the container release another particle once per hour to much oftener, even if the container is much smaller.
    That is about a millionth of the estimated density of interstellar space around us. Can you provide a reference? I cannot find any mention of a laboratory vacuum chamber that even comes close to interstellar space, not to mention your reputed one.

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    I confess I was shooting from the hip.
    I don't think we know that none of the extrasolar planets (found so far) have a million bar atmosphere above a rocky surface.
    Sorry I don't have a reference, but I understand that intergalactic space is thought to have much less dust and smaller stuff than typical in our solar system. I think only educated guesses are possible with present technology.
    I was trying to illustrate that greenhouse gases have only modest ability to make a planet hot instead of the near infinate ability implied by some green house alarmists. Neil

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    Quote Originally Posted by neilzero View Post
    I confess I was shooting from the hip.
    I don't think we know that none of the extrasolar planets (found so far) have a million bar atmosphere above a rocky surface.
    Sorry I don't have a reference, but I understand that intergalactic space is thought to have much less dust and smaller stuff than typical in our solar system. I think only educated guesses are possible with present technology.
    I was trying to illustrate that greenhouse gases have only modest ability to make a planet hot instead of the near infinate ability implied by some green house alarmists. Neil
    But million bar atmosphere will certainly heat up planet more if 90 bar CO2 = + 650 K

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    Quote Originally Posted by m1omg View Post
    But million bar atmosphere will certainly heat up planet more if 90 bar CO2 = + 650 K
    That's a little like saying that a million coats of whitewash will make your fence whiter than just 90 coats.
    At some point the absorption bands for CO2 will saturate: they'll be absorbing all the IR radiation in that part of the spectrum, and additional CO2 can't do any more than that.

    Grant Hutchison

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    Quote Originally Posted by grant hutchison View Post
    That's a little like saying that a million coats of whitewash will make your fence whiter than just 90 coats.
    At some point the absorption bands for CO2 will saturate: they'll be absorbing all the IR radiation in that part of the spectrum, and additional CO2 can't do any more than that.

    Grant Hutchison
    When it will be saturated?

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