Underground Skybox/Fog Light

I don't like how with a lower render distance (8 chunks) you can see the skybox/fog when underground. During the day it's bright blue, but at night it's black so it's fine. I think it should be made that when you are underground or at least at a certain Y-level it changes completely to black. This would make the Deep Dark more immersive, and actually give the clock item some more use, since you currently don't need it when underground as you can just look at the skybox/fog.