cloud question

[andytheplumb]

anyone know why clouds look bubbly on the top and flat on the underside ???

[Clanad]

Not all clouds do, by the way. But, clouds develop when rising air reaches its dew point and begins forming small droplets of moisture known as clouds. Therefore, since all, or most, clouds form at about the same altitude (depending on the dew point) they all tend to have the same baseline and appear flat. this is most noticeable with the boring Stratus clouds. Any rising air tends to lift the body of the clouds unevenlingly producing the puffy tops
Here's some pictures of clouds with fluffy bottoms
http://australiasevereweather.com/photography/ mammatus/mammatus_cloud0339.html .

[Catso]

Or to put Clanad's answer another way:

A warm, moist 'bubble' of air rises. As it does, it cools, because the atmosphere gets gradually cooler as you go higher. There comes a point where the moisture starts to condense out and become visible, forming a cloud. Because this happens at a certain temperature - IE a certain height - the clouds have flattened bottoms.