You might say that if you have never lived among steep mountains in a climate blessed with humidity and precipitation.
Let me get on with it.
On the ground it may as well be fog. Can’t see blue sky or sun. Can only see 50 meters in front of me. Definitely fog.
Or is it?
I live at 600meters above sea level in that fog.
For me the question of fog or clouds is one of the pleasant riddles of life. Hope you have found it the same.