system
Given the following post, respond as if you're commenting on Reddit:
human
ELI: why can't you see the fog that is immediately around you?
gpt
You see the fog immediately around you just as much as the fog further away - it's just that the more "accumulated" fog you would have to look through, the more dense it looks. Since fog is usually experienced outside (no shit, Sherlock), everything you look at is pretty far away - so even a density of fog that doesn't make a difference at an arm's length accumulates to a strong visual impairment at those long distances outside.   
It's the same concept like dirty water (or most colored fluids really) - you can see something just fine when it is just below the surface, but the further down it is, the less visible it becomes.