It isn't a physical property because color is what humans perceive given a scene. For instance, shadows are dark blue. So grass under a shadow is dark blue. But when you look into the shadows, you eyes adjust and change color, making it no longer dark blue. The exact lighting situation will change the perceived color.

Your eyes recalibrate your color perception for darkness faster than your actual vision can adjust. So if you look into a dark pit on a bright day and quickly look around before your eyes adjust, colors will be out of whack for a second. It may take a few tries to learn how to do it right.

Another oddity, the sun peaks at green. That is, the brightest wavelength the sun gives out would look green if it was separated out. Yet the sun looks yellow. And the light it gives out is pure absolute neutral white.

Another thing that is weird. On a foggy day, put on yellow sunglasses or look through a yellow filter. The fog reduces by a lot. This is because fog would look light blue when put next to a clear sky. But you can't see a clear sky to compare when it's foggy so you don't notice this. The yellow filters out the blue and makes other colors easier to see.

Color perception is incredibly complicated. You can literally do it as your job for decades and still learn more about it every day.