Jack July

Where were you on the night on June 11, 2011? Were you in your hometown of Schiffdorf, northern Germany, contemplating the possibility that the excellent light conditions and passing storms would provide an excellent opportunity to capture a double rainbow? An elusive tertiary rainbow? Or even the as-yet-unobserved quaternary rainbow? 

Journal of Applied Optics and the BBC report today that a quaternary rainbow has for the first time been observed in the wild. The first two rainbows appear behind the observer-away from the sun, where most rainbows are seen; the third and fourth are pictured. Notice that the color patterns are inverted between the two rainbows, owing to the fourth having refracted out of water droplets in the opposite direction of the third.