Not sure if this is the best place to ask. Apologies if not.
(Assume this is under generally average conditions)
Say you have an object that is 1 metre in front of you. When you see that object, how much of the light your eyes are perceiving has been altered in some way, e.g scattered or absorbed, by the air around you? I assume it is negligible? Could a rough percentage be calculated?
Usually it is negligible. But on a foggy day...
You can tell because the object doesn't change its appearance when you move it two meters away.
On a foggy day, it fades into the fog as you move it farther away. The fog scatters light. More fog means more scattering, so less light from the object reaches you.
Underwater, light can be absorbed, especially at the red end of the spectrum. See Why ocean appears blue?. Try putting a red object at the bottom of the shallow end of a swimming pool. Then move it to the deep end. It should look noticeably less red because water absorbs red light over a few meters.
Air does the same thing, but the wavelengths it absorbs are in the UV or infrared. These are colors you can't see, so you don't notice their absence.
Over a longer interval - miles - air does change the color of light. This is due to Rayleigh scattering. A little light scatters off dust in the air. Short wavelengths are scattered more than long wavelengths. This make the sunset red. The only light from the sun that makes it to you is red.
It also makes the sky blue during the day. Lots of light from the Sun isn't directed toward you. Ordinarily you wouldn't see it. But in any patch of the sky, some of the light passing through is scattered, and some of that is directed toward you. You see that light coming from a patch of sky where there is only air. Since shorter wavelengths are scattered most, the light you see is blue.
