color of the sky

when talking about what color provides the highest visibility, a fellow said that where he flies, the sky is dark blue.
and this made me think about it.
is it possible that the blue of the sky could be darker or lighter depending on the surroundings? i mean, during the day.
i remember when i lived in vancouver bc, that there was always a thin layer of mist, so the sky looked pale blue. but besides this, i dont recall seeing the sky dark or light when no clouds or mist is present.
so, what is your experience?
i started a thread here but became contaminated by non-sense so i had to close it: https://www.rcgroups.com/forums/show...he-sky-is-blue