Shown is a sunset at the base of stratocumulus clouds, one of the most common clouds types along cool-water coastlines such as the U.S. and Mexican Pacific coasts. Sunsets often appear red or reddish-orange because airborne particles are absorbing the shorter wavelengths of light: violet, blue, and green. Reddish colors are most common during sunrise and sunset-when the sun is closest to the horizon-because the sunlight is passing through a high density of airborne particles in the lower atmosphere, allowing more absorption to take place.
Courtesy of Carlye Calvin/UCAR