Primary, Secondary and Supernumerary Rainbows

October 04, 2015


Photographer: Greg Parker
Summary Authors: Greg Parker; Jim Foster
The photo above featuring an impressive primary rainbow, secondary rainbow and supernumerary bows was captured over the New Forest Observatories near Brockenhurst, England, about an hour before sunset on July 26, 2015. The supernumeraries are the thin bands just inside the inner edge of the primary bow, adjacent to the violet band. They form as a result of how waves of light interact with small water drops unlike the primary and secondary bows that result from refraction and reflection of light inside larger raindrops. They're more pronounced it seems when the drops are similar in size, ranging from approximately 0.5 mm to 0.7 mm in diameter.