Thought you were a pilot, Cit?
In the SE USA I have seen VFR conditions that presented a 'murk' which made it impossible to make out any kind of landmark from only 8,000 feet. Probably, humidity helped to create a blanket of pollen and dust that obscured the view, but conditions can get so bad that even the horizon is obscured. That's today. In 1941-1945 pollution was much worse.