While the overcast model is a lot better than in standard XP I noticed it struggles in situations where it's intersecting with the ground.e.g. mountains. I made a short video that illustrates the problem: I used all default settings, except overcast quality=high and god rays=off. It seems like when I'm inside the overcast layer any portion of the terrain that is intersecting the layer suddenly becomes visible while it remains invisible from outside the layer.My weather and rendering settings were as follows: Also, when I select "stratus" instead of "cumulus ocast (bumpy)" for the lowest layer I don't see any difference between overcast quality "low", "medium" and "high". All just create a zero-thickness layer at the base which looks rather unrealistic, especially during transitions. Apart from this, it is a *HUGE* accomplishment, congratulations! Finally getting rid of the dreaded "grey screen of death" was well worth the money in itself ;-)