24 Jun 10
Originally posted by joneschrOnly if the average density difference is minimal. If there is a significant difference then there will be a down-draft. Because of drag, the water will pull the air down with it.
Yes, the cloud would fall. But at an extremely slow rate - as I posted earlier, a cloud will naturally fall from gravity. But again, because of drag, it would take a couple of years to reach the ground.
24 Jun 10
3 edits
Originally posted by KazetNagorra
If it was just drag, then air would fall to the surface, eventually. It doesn't, because of pressure.
Air is a gas. Water droplets in clouds are a liquid. Water droplets aren't affected by pressure. You can't compress water.
Yes, if the air contained in the cloud dropped because of a change in pressure in the air below the cloud, the water in the cloud would drop along with the air (And indeed, clouds tend to fall during the evening and rise during the day). But that's a different issue than the OP's issue of why the water in the cloud doesn't crash to the ground.
24 Jun 10
Originally posted by joneschrWell, small water droplets are not unaffected by pressure, of course. But apart from that, the density in water droplets is still much higher than in the air around it, so you're right it's drag holding them up.
Originally posted by KazetNagorra
[b]If it was just drag, then air would fall to the surface, eventually. It doesn't, because of pressure.
Air is a gas. Water droplets in clouds are a liquid. Water droplets aren't affected by pressure. You can't compress water.
Yes, if the air contained in the cloud dropped because of a change in pressure ...[text shortened]... an the OP's issue of why the water in the cloud doesn't crash to the ground.[/b]