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Thread: How much does surface pressure contribute to Venus's temperature?

  1. #1
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    How much does surface pressure contribute to Venus's temperature?

    If Earth's atmosphere were as dense as Venus's, what would its temperature be?
    "Occam" is the name of the alien race that will enslave us all eventually. And they've got razors for hands. I don't know if that's true but it seems like the simplest answer."

    Stephen Colbert.

  2. #2
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    See: No, pressure alone does not define surface temperatures!

    And: The runaway greenhouse effect on Venus

    (ETA: the rather elderly graph on the second webpage suggests that 93 bars of Earth's current atmospheric composition, which would be about 40mbar carbon dioxide, would yield an average surface temperature around 320K through greenhouse effect. But I'm guessing that's not the question you're asking.)

    Grant Hutchison
    Last edited by grant hutchison; 2020-Sep-05 at 11:21 PM.

  3. #3
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    No that's exactly what I wanted to know. Whenever I mention Venus in my videos I get comments from climate change-denying morons saying that Venus's temperature can't be due to CO2. When that happens I feel obligated to answer them to prevent the spread of misinnformation. This was just one I didn't have the knowledge to answer myself, so thanks :-)
    "Occam" is the name of the alien race that will enslave us all eventually. And they've got razors for hands. I don't know if that's true but it seems like the simplest answer."

    Stephen Colbert.

  4. #4
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    Well, if you respond, you'll just give them the opportunity to say more crazy stuff.
    I take it you are unable to moderate the comments on your videos? Killing the crazier stuff before it clears the moderation queue is a much better way to retain your sanity.
    There are plenty of actual atmospheric scientists around who are doing sterling work responding to this nonsense on their own blogs and channels, so I wouldn't feel any moral obligation to try to engage when you're outside your own area of knowledge--these folk have a playbook they work from, which is essentially designed to lure people into debate and then push them quickly into complicated areas that require expertise to negotiate.

    Grant Hutchison

  5. #5
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    I can moderate. Any insults I remove without discussion. I don't really mind most fringe loonies. Even the EU people have calmed down in the last few months. It's only when they start to get into topics that can actually have real world impact that I start to worry, though I prefer to respond to those comments rather than delete them, because if I can't challenge a stupid idea, then I shouldn't be doing what I'm doing.
    "Occam" is the name of the alien race that will enslave us all eventually. And they've got razors for hands. I don't know if that's true but it seems like the simplest answer."

    Stephen Colbert.

  6. #6
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    Well, good luck with that.

    On the whole "atmospheric pressure makes Venus hot" thing, it seems to be based on a misapplication of the gas laws. Sure, if you compress a gas adiabatically, it gets hotter. But planetary atmospheres are not closed systems--they're in thermal equilibrium with their surroundings. Your bicycle tyre may get warm when you inflate it, but it doesn't stay warm. And the emergency oxygen cylinder on my anaesthetic machine had an internal pressure of 137bar, considerably more than the surface atmospheric pressure of Venus, but it quite noticeably wasn't hot enough to melt lead.

    Grant Hutchison

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