visbility range

[codman]

Just got done playing a battle in a campaign where the visibility was 3 hexes. Oddly enough throught the battle there were times when one of my units could see much farther then 3 hexes and I was wondering if the visibility is a variable that changes during the battle. Not all of my units seemed to benifit from it even if they were in the same hex and because it's 1958 I doubt that they were getting any type of bonus for IR or NV. I was thinking that in this case the game was trying to simulate an overcast day with lots of blowing fog or scattered rain showers. Any info would be great as I thought it was kind of neat.

Thanks in advance

Steve