Clouds

[aceizace]

Sounds like a silly question, but hear it out. Why do clouds stay floating in the air? I actually got this from Red Dwarf's 'The Log'. He is talking about when your children ask you questions you can't answer: 'Well you see son, clouds are made of water vapour, which is denser than air so... why the hell are they up there? They should be down here!'. Not even my biology teacher could come up with a decent explaination, any thoughts?

[wildwood]

This is just a thought, but maybe because it is colder up there than down here. Cold air can hold a lot more humidity than warm air.

[aceizace]

Hmm, intresting. How do you mean 'hold humidity' though? While water vapor condensing onto glass, for example, makes sense to me, simply forming in mid-air instead completely baffles me! :-S

[Rabelais]

Water vapour is infact lighter than air, but in this case that matters not, clouds are composed of microscopic water droplets and/or at higher altidtudes/lower temperatures tiny ice crystals which are quite happily kept bobbing about by the gentlest of updraughts. Clouds form when air rises (usually due to convection or being forced over a slower moving more dense air mass) this then forces condensation which liberated the latent heat of the vapour (this is the additional energy that means a steam burn makes a boiling water burn seem like a walk in the park given the overall molecule to skin ratios involved) This means clouds are roasty toasty warm in comparison to the air before the droplets condensed meaning the become less dense that the surrounding air allowing them to rise.

[tief]

I like my daughter's answer to that (when she was two). After she'd asked me that same question and I was madly trying to think of an answer she might understand, she came up with her own answer ... "It's so everybody can see them!"