Spring RTS Engine

How hard would it be to make a cloud gadget? I would like to have variable size and shaped clouds that have controllable movement and size (they could default to drifting in the wind...) and look like the fog widget's proper fog (only not a plane but a 3d object, obviously).

Is this doable? How much of a performance hit would it be?

This along with revamped snow gadget could make for fun times with better dynamic weather simulation, imagine a rainstorm or a blizzard or a SANDSTORM!

This screenshot was found in the CA gallery under the title "unreleased clouds widget." I don't know anything about it, but I'll bet jK or lurker would.

while searching around on this topic i found mentions of a cloud shadow widget, I assume that is what the pic shows. The default skyboxes have dynamic clouds, its probably related to that. They aren't exactly what i had in mind tho, unless they have hitherto unknown customization options.

I actually made a cloud widget, but it was terrible, looks terrible, and causes a 300% decrease in FPS. Plus it crashed the game alot. I would appreciate if someone who knew how to do this would do it. I want a weather system that I can control using gameplay elements. I have a sort of "spiritual" faction that is rather hard to detect with sensors, but clouds brewing overhead would be an epicly awesome way of showing where they are.