[robski]

Atmospheric haze is mainly due to light scattering by moisture in the air. In effect what your asking for is a filter that can see through fog.

Time of day may have some effect on the moisture levels but often the air is much clearer after a good rain downpour.

Another thing worth checking is the on-line weather forecasts, many give a visibility rating. Either as distance in miles or very good, moderate, poor,etc.

Of course the other enemy of distance photography is heat haze caused by hot air circulating.