What makes CLOUDS keep their irregular shapes?

The shapes of clouds are in constant change due to lift(rising of warm air) and winds if you watch a cloud very closely you can see the affects of this or even better do a time lapse photos it is very interesting to watch clouds change you can even see cold funnels apear in cumulonimbus clouds just watch very closely.

To learn more on clouds see this link

http://www.srh.noaa.gov/srh/jetstream/synoptic/clo...

Well, that's the thing. Clouds aren't just water vapor. Clouds have condensed. They aren't a gas anymore. When you watch steam from a pot, that is water vapor, and it does "merge" with the surrounding atmosphere. But you don't see a pot of water merging.

The big puffy clouds also keep their shapes through convection (basically lots of water evaporating). The wind can also shape clouds, which gives you the more streaky kind of clouds. Wind also can keep clouds from building up. That is why in higher pressure, clouds don't get very large, because the pressure and wind won't let them. If there was not wind, the clouds can build up and produce rain.

Nothing makes them keep irregular shapes. They actually DON'T keep any shapes. If they kept regular shapes, that would be something to wonder about.