Multiple Bows from a Water Hose
July 24, 2002
This photo was a result of an experiment with a waterhose to see how many interference bows were possible in a rainbow. The water droplets were of even size and created multiple interference or supernumerary bows inside the primary bow as well as the interference bow outside of the secondary bow (lower lefthand corner). This bow is rarely seen in a natural rainbow.
Supernumerary bows can only occur when raindrops are uniform in size. According to David Lynch, coauthor of "Color and Light in Nature," they're caused by the interference between two parts of a light wave that have passed through a water drop along slightly different paths. These two rays emerge from the drop at approximately the same position and interfere with each other. As is shown on the photo above, several orders of interference may be seen.