Vision greater then 40; what does it really mean in game terms?

[Wdll]

There is also a matter of improved vision through smoke and some terrain (trees). I think you need 40 to see through smoke and for the other, it depends but I don't know exactly how.
Not sure if it also smoke cuts on the distance 8 vision due to the weather, 40 vision for the system due to thermal imaging, smoke at 7 or 10 distance, final view distance still 40? Funny I haven't checked it yet lol.