Higher Layer of Clouds (Perhaps as a Skybox, Shader, or Something)

Personally, I think it would be nice to have a logical reason why it rains or snows above the cloud layer.
Perhaps a reasonably simple-ish (maybe) way to do this would be to have something like a bunch of purely visual far off rectangular "clouds" as additional layer that rotates around basically at the skybox level, but in front of the sun/moon. This could give the impression that rain and snow are coming from somewhere that the player (presumably) can't reach, unlike the current clouds.