Substances don't have a single "color". Air, for instance, scatters blue but transmits more red. So if you look at a light source through a lot of air, it's red

Substances don't have a single "color". Air, for instance, scatters blue but transmits more red. So if you look at a light source through a lot of air, it's red (such as a sunset) and if you look obliquely to the light source, it's blue.