Confirmed. Seems to be related to the light level: if you got into a dark cave but can still see the horizon, the fog becomes completly black. It is also noted as a feature of 1.7 on the wiki, which is weird. I hope it's not, because it sure is ugly!
I think like @Sebastian Romu that it's for fixing the fog when underground, but they didn't think it through very much and didn't notice it affected above-ground fog as well.
I actually find that the bright fog underground was a good thing, it gave some kind of mystical side to those caves, so this "fix" in itself wasn't a good idea to begin with...
Confirmed. Seems to be related to the light level: if you got into a dark cave but can still see the horizon, the fog becomes completly black. It is also noted as a feature of 1.7 on the wiki, which is weird. I hope it's not, because it sure is ugly!
I think like @Sebastian Romu that it's for fixing the fog when underground, but they didn't think it through very much and didn't notice it affected above-ground fog as well.
I actually find that the bright fog underground was a good thing, it gave some kind of mystical side to those caves, so this "fix" in itself wasn't a good idea to begin with...
Wait & see.