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Why doesn’t rising temperature cause the atmosphere to expand outward? Or does it?

  1. Nov 30, 2017 #1
    First, I am not a scientist, so this may be a stupid question. But with all the concern about global warming - and given that temperature and pressure are related - why doesn’t rising temperature cause the atmosphere to expand outward and the temperature to fall as a result, back to an equilibrium? After all, earth is surrounding by the vacuum of space.
     
  2. jcsd
  3. Nov 30, 2017 #2

    russ_watters

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    Staff: Mentor

    Welcome to PF!

    The answer is: it does! And not just due to global warming, but due to weather and solar activity.

    Interestingly, google tells me that overall global warming will (has?) cause the atmosphere to contract because the warming happens low in the atmosphere, which then causes cooling in the upper atmosphere:
    http://www.ucar.edu/news/releases/2006/thermosphere.shtml
     
  4. Dec 3, 2017 #3
    https://en.wikipedia.org/wiki/Skylab

    Came down rather earlier than NASA expected due 'solar cycle' inflating upper atmosphere and significantly increasing drag.

    Upside of this effect is each 'Solar Max' clears a lot of debris from low orbit. Down-side is we may be facing a 'long minimum'...
     
  5. Dec 10, 2017 at 6:40 PM #4
    To help understand it's important to remember the atmosphere is about 300 miles thick. To put that in perspective the international space station orbits at 254 miles, so it's technically not even in outer space yet. Though the vast majority of the atmosphere is kept much closer. So the density changes a lot which also has an effect on temperature.

    It's important to understand that a high temp and heat are not exactly the same. Temperature indicates how quickly atoms are moving. Heat indicates it's impact on the body. As you go up in altitude it gets colder decreasing in temp. But when you hit the stratosphere the composition of air changes and temp actually starts to increase. At the top of the stratosphere the temp is basically the same as ground level. But the air is so thin that high you'd still freeze to death.

    So if the atmosphere were a uniform gas it would expand and contract due to temp such as you'd see in air in a balloon. But the atmosphere is a bit more complicated and requires further explanation.
     
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