Blue Skies and Red Sunsets

The complementary affect of the blue sky is the red sunset or sunrise. At sunset the light from the sun reaching the observer has traveled through the most atmosphere possible and has had most of the blue component of the white light scattered resulting in predominately red light reaching the observer or illuminating clouds that the observer can see. The light at sunset is more likely to be red than sunrise because the turbulence in the atmosphere during the day can mix more particles into the atmosphere which enhance the scattering.