Chapter 5: Q23DQ (page 1104)
The explanation given in Section 33.6 for the color of the setting sun should apply equally well to the risingsun, since sunlight travels the same distance through the atmosphere to reach your eyes at either sunrise or sunset. Typically, however, sunsets are redder than sunrises. Why? (Hint:Particles of all kinds in the atmosphere contribute to scattering.)
Short Answer
The sky is red at sunset because there is a greater number of suspended particles in the atmosphere to carry out the scattering process of the blue light.