• Question: how much does our atmosphere/air weigh?

    Asked by Steve to Alan, Ciorsdaidh, Lauren, Leonie, Martin, Neil, Shuo on 6 Mar 2018.
    • Photo: Martin McCoustra

      Martin McCoustra answered on 6 Mar 2018:

      Air is surprisingly heavy! If you imagine a column of air 1 cm by 1 cm stretching from the top of your head to the edge of space then it would weigh roughly 1 kg! A 5 cm by 5 cm column would weigh 25 kg! So there a lot of weight pressing down on your head!

    • Photo: Neil Keddie

      Neil Keddie answered on 8 Mar 2018:

      Lets assume (as an approximation) that our atmosphere is 79% Nitrogen and 21% Oxygen (let’s not worry about the small fractions of argon, CO2, and water vapour right not).
      1 mole of any gas occupies a volume of 24L at standard temperature and pressure at sea level.
      So for 1 mole of a gas mixture of 79:21 N2:O2 the masses of gas would be 22.12g N2 and 6.72g O2 – so that 24L of gas would weigh 28.84g (and 1L would be 1.2 g)
      Now imagine how amazingly big the atmosphere is, and think how small 1L is (it’s just a 10x10x10cm box) – you need to do a lot of multiplication now.

    • Photo: Alan McCue

      Alan McCue answered on 9 Mar 2018:

      Awesome question. I had to look this up and found the following:

      The total mass of Earth’s atmosphere is about 5.5 quadrillion tons, or roughly one millionth of Earth’s mass. Air is heavier at sea level, since the air molecules sit close together, compressed by the weight of air from above. As elevation increases, however, air molecules grow farther apart, and the air becomes lighter.

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