An Aid to Thought

Over at “wattupwiththat”, a commenter opined some time ago:

I remember when I was a kid playing with a bicycle pump that compressing a gas heats it up. Is it possible that some of the high surface temps on Venus are because of that pressure?

Why not have a cold beer to help think that one through?

Wesley R. Elsberry

Falconer. Interdisciplinary researcher: biology and computer science. Photographer. Husband. Christian. Activist.

5 thoughts on “An Aid to Thought

  • 2009/04/27 at 12:21 pm

    The same principle worked to warm the air flowing out of the mountains in Colorado.

    Some I suspect that as atmosphere moves up / down cooling and warming takes place from expansion and compression just as it does on earth. Although, I suspect that venus is warm/hot becuase of the abudnance of greenhouse gasses and proximity to the sun.

  • 2009/04/27 at 2:27 pm

    The main thing I was critiquing was the notion that the Pv = nRT at time of compression has much if anything to do with the value of T some millions or billions of years later. The fact that the CO2 in a beer had to be pressurized at some point doesn’t mean the beer can never thereafter be cold.

  • 2009/04/27 at 5:26 pm

    Quite right. I got your point. Mine was to acknowledge that localized adiabatic heating of the atmosphere is likely ongoing on Venus similar to the Earth. But that such a process was a result of a more dominant weather system on Venus driven by solar radiation, as on Earth. And that a dose of greenhouse gas heat trapping exacerbates Venus’ plight.

    But of course, you already know this.

  • 2009/05/08 at 1:11 am

    But what if (starting at room temperature and pressure) you were compressing hydrogen or helium?

  • 2009/05/09 at 5:03 am

    There’s nothing special about hydrogen or helium with respect to change in temperature with change in pressure.

    When I get a SCUBA tank filled, air is pressurized to a bit over 3000 PSI. The tank gets noticeably warm. Most places put tanks being filled in a water bath, which is far more effective at distributing heat from the tank than air. But either way you go, the tank of pressurized air doesn’t remain at a high temperature; it eventually equilibrates with ambient temperature. The internal pressure is still at 3000 PSI, but there’s no persistent temperature increase due to the fact that it is under high pressure.

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