Sky color at sunrise and sunset

[PlutonianEmpire]

I've noticed that the sky color, at both the horizon and the sky, at sunset appears slightly different from the colors at sunrise, at least to me. Why is that?

[Hungry4info]

I've noticed and wondered about the same. My guess is that throughout the day the influence of solar irradiation on the atmosphere changes how it interacts with the light from the sun, perhaps having something to do with man-made emissions over the last however long.