Blue Skies & Sunsets

The figure on the left shows that the perceived color of light reaching your eyes when in this position relative to the sun's rays is blue. The reason for this is that the atmospheric scattering of blue light away from the forward direction is much stronger than for red light. The figure on the right shows that the perceived color of light reaching your eyes when looking at the sun near sunset is red for essentially the same reason; much less of the red light is scattered out of the direct beam compared to the larger scattering for blue. The sunlight has the deepest color of red right at sunset when the rays travel through the greatest amount of air before reaching your eyes. Red sunsets are also enhanced by particulate matter in the atmosphere.