Improved fog effect using alpha-blending

One thing that always bugs me is that the single-color fog effect never matches up with the sky. You can always see the outline of distant objects clearly against the sky, no matter how far away they are. Instead of using a solid fog color, couldn't distant objects be alpha-blended with the sky layer? I'm no graphics engine expert, but I wouldn't think this should be too hard to implement.

Naturally this would mean creating a "lower hemisphere" for the sky layer, as it appears to be pitch-black currently (as can be seen by flying very high).