Problem:
I have a question about the mechanics of human vision which may be as much of a physics question as it is a biology/physiology question. I noticed that if I try to imagine a clear blue daytime sky contrasted with a clear night sky and ask myself which of the two appears closer, my intuition says the daytime sky appears closer. My next thought was, given that a night sky is mostly black, visually the only difference between the two skies is their color. So why is that I want to "blue" is closer than "black"? And if the difference in color is truly what produces the difference in perceived depth, can similar effects be noticed with other color pairs at more familiar distance scales?
But then again, there are a couple of alternative explanations that seem more plausible to me on second thought. A black night sky could just as easily be called a dark sky, and the difference in perceived depth is really more a matter of shading. Then I remembered a night sky has stars of course, and it might be that my mind just wants to place the stars at normal "sky depth", forcing the black backdrop to appear even further away.
Explain the difference between the two skies is sky color.