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Let's have an easy one. Being made of tons of condensed water, what keeps clouds floating serenely above instead of plummeting to Earth?
Question
#62366. Asked by gmackematix. (Feb 08 06 1:28 AM)
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gmackematix
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Yay Mochyn! Sounds good "for one sort of cloud".
Doesn't that make you wonder what happens in other sorts?
As I had read it, as the water vapour rises and cools it condenses into droplets of water.
When bonds are formed, heat energy is released, so the formation of water droplets sends heat into the air, making it slightly warmer and hence, slightly less dense than the surrounding air.
So clouds are composed of a colloidal suspension of water droplets in warmer air which is lighter and floats in the cooler air.
Hang on, is that right? Oh it's far too late for this now, I'll go and sleep on it.
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gmackematix
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Having slept on it, I've decided that invisible winged angels hold them up with nets.
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Baloo55th
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It's a bit like a ton of iron and a ton of feathers. The tons of water in the clouds are very widely dispersed. If you've ever walked through a cloud, you'll not find anything heavy there. (Yes, you have. A lot of fogs are merely ground level clouds.) There are also uplift effects from rising currents of warmer air which keep the droplets up there. When you don't, and there are enough droplets, they come down as rain. Very simplified. For more details, see Collins Gem on Weather. Written by (believe it or not) Storm Dunlop.
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gmackematix
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Sorry. That is a common but nonetheless faulty argument. A ton of feathers doesn't float and nor would a ton of water droplets if it wasn't for the atmospheric effects of condensation on the surrounding air as described above. Continual updrafts that keep a floating cloud at its level are as unlikely as they sound.
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Baloo55th
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"In warm clouds that are never below 0 degrees C, droplets grow by collision. The process is enhanced by large initial droplets (over 20 micrometers), plentiful water in the clouds, and moderate updraughts. The updraughts are important because they sweeo small droplets past larger ones and increase the chances of collisions. When the weight of suspended droplets becomes too high, the updraught collapses and there is a sudden shower." (Page 145) The comment about feathers was because feathers are less dense and have greater air resistance. Droplets of water have a larger surface area in total than the same volume of water in one lump, and will have greater air resistance as a result. A ton of raindrops in a cloud will occupy a large volume, unlike the same ton of water when it has landed in a convenient previously empty tank.
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