There are many different kinds of rainbows. In addition to a primary rainbow, which is the most commonly seen, there are also secondary rainbows that occur when two reflections take place in a water droplet. Then there is the monochrome rainbow. These happen at sunrise or sunset, when the shorter blue and green wavelengths are scattered out before they reach the water droplets. Hence, the human eye sees only red. This unenhanced image was taken on July 6, 1980, just outside of Minneapolis, Minn.