Finally found a pretty good solution for animation in a cloudy environment. I’ve tried doing some animations using halomaterial, but I’ve always had some problems (halo “image” rotates with the camera, and is the same for each vertex).
But, if you apply a cloud texture to concentric spheres, and restrict the camera to travel within the smallest of these spheres, you can get something like you might see out of the window of an airplane.
Here’s a simple .blend file that demonstrates this:
No animation file, but you can render one yourself pretty quickly with the above.
Haven’t been able to find anything quite like this in the forums, but it seems so simple now that I wouldn’t be surprised if it’s already been done.