• Zeppo@sh.itjust.works
    link
    fedilink
    English
    arrow-up
    78
    ·
    11 months ago

    The good news is we’d be pretty dead if we had no atmosphere anyway, plus there’d be no clouds.

  • cheery_coffee@lemmy.ca
    link
    fedilink
    arrow-up
    31
    ·
    11 months ago

    Even without air resistance rain wouldn’t come at once.

    Depending on how literally you take “no air resistance” it could mean no wind at all to no friction to slow rain.

    In the first interpretation water vapour goes up straight continuously and creates layers of density proportional to the amount of sun/heat hitting the lake. Eventually the vapour reaches critical altitude and accumulates there.

    Because evaporation is always happening and moves discrete particles of water randomly, there would still be particles if water coalescing into drops of rain. Think of it kind of like the same effect as raindrops hitting your windshield and combining until they get heavy enough to slide down, not a wall of water.

    And in the second interpretation I hope it’s now clear that this would result in painful rain drops with high velocity, but still not a thick sheet of it.

    • Nougat@kbin.social
      link
      fedilink
      arrow-up
      9
      arrow-down
      1
      ·
      11 months ago

      If there wasn’t an atmosphere to provide resistance, there wouldn’t be water vapor suspended in it, there wouldn’t be dust particles suspended in it to provide places for condensation to happen.

      With no air resistance, there wouldn’t be rain in the first place.

      • cheery_coffee@lemmy.ca
        link
        fedilink
        arrow-up
        4
        ·
        11 months ago

        I took the liberty of assuming there is air, it just doesn’t “move” or impede the process of evaporation.

        You can evaporate water in a vacuum, so you could have an atmosphere with no other gasses than water and still get rain. The process of condensation should still work. I think the concept of air gets weird though…

        https://physics.stackexchange.com/a/424193

    • BarrelAgedBoredom@lemm.ee
      link
      fedilink
      arrow-up
      4
      ·
      edit-2
      11 months ago

      They mentioned a 2 in. thick sheet of rain falling, which is ~288 cubic in. per 1 foot x 1 foot area, about 10 lbs of water. Falling as a flat sheet at terminal velocity would hit you with a force of 127 newtons. What that means as far as injuries go I have no idea. I’m sure it’d cause a nasty headache at the least though.

      Fair warning, I’m terrible at math so I could be completely wrong

      • SmoothLiquidation@lemmy.world
        link
        fedilink
        English
        arrow-up
        5
        ·
        11 months ago

        Terminal velocity is only as fast as it is because of air resistance. With no air resistance, the only limiting factor of speed is starting height.

        It’s like the experiment with the feather and the hammer they did on the Moon.

        • BarrelAgedBoredom@lemm.ee
          link
          fedilink
          arrow-up
          1
          ·
          11 months ago

          I did tweak the drag coefficient while doing the math but I had no idea how to figure out what would be most accurate. The number I got there is with a drag coefficient of 1

      • DaCookeyMonsta@lemmy.world
        link
        fedilink
        arrow-up
        3
        arrow-down
        1
        ·
        11 months ago

        Energy would be better to look at than force, since at any distance the force is the same (mass and acceleration aka grsvoty are both static)

  • Kaity@leminal.space
    link
    fedilink
    English
    arrow-up
    1
    ·
    9 months ago

    Reminds me of that page in the Bone comic where the snow comes down all at once. I loved that scene!