Making a cloud

Does anyone have good idea for dynamically making and rendering a cloud?
I want it to be partially transparent, to move according when forces are added etc.
I thought about particles emitting meshes with maybe a collider and a script attached to manage movement. But I’d need thousands of particles.
I may need to make thousands of these at once, though they will be rendered rather small.

Any ideas on what I can look at or where to begin?

Perhaps this thread could be of use:
http://forum.unity3d.com/viewtopic.php?t=8881

Not quite what I want, but very close. Thankyou very much. :slight_smile:

EDIT:
Actually it works quite well once I worked out how to re-make it from scratch. :slight_smile:
Thanks!