gnu - What I meant was what they might do in, say, the next 5 minutes or so. ;-) That is, they might move this way or that way, at this or that speed, they might thin out some, they might thicken up some, they might combine or separate, etc...and that would depend on a number of different factors. If I wanted to know exactly what they would do, I'd have to sit there and watch them do it to find out. Direct observation would definity yield a more certain answer than theorizing about it...or calling up the local weatherman and asking him. That's why I say, nothing beats direct experience.

You could say that clouds evaporate, and you'd be right. You could also say that they form and you'd be right again, only at a different time in the life of the cloud, that's all. ;-) We also form and then we evaporate at some point. It's called birth, growth, life, aging, and death. Everything in this world appears to do that, although some substances (like gold) are very stable. If I may quote Mr Dylan again, "everything passes, everything changes".