Posted this problem recently but only partially cured it. It seams no matter what weather theme i use other than fair weather or totally clear, i get a heavy haze with poor visibilty at low altitudes. If i stick to fair weather,that's the cure and i get clear atmosphere and nice blue sky with a few clouds. If i want to increase my clouds i have to go to a theme or user defined and in comes the haze. I am using REX2. Could that have anything to do with it?

did u check the low visibility in rex config manager ?