This picture was taken while I was on family vacation in Virginia, summer 2006. We were at an overlook in Comers Rock. You're supposed to be able to see clearly the third row of mountains (click the picture for a full-size image, then look at the dim outline that represents the third row of mountains). The locals tell me that the reason you can't see so far some days is because of pollution. We had the same limited visibility problem on the Blue Ridge Parkway. What a shame.
While pollution might make for great sunsets in California, it's not helping the scenery in Appalachia.