Abstract

We frequently see reports of rainbows that don't appear to display the "usual" sequence of colors. Bows are reported with some colors missing and others are described with certain colors enhanced in brightness. We understand some of these reports qualitatively. For example, the red rainbow results from atmospheric scattering that selectively removes the blue end of the spectrum from the sunlight incident on the raindrops. The usual explanation for other reported variations is that the appearance of the bow depends somehow on the droplet size. This is a kind of shoulder-shrugging explanation that requires no understanding from the explainer and gives no insight to the listener. We do understand something about the transition to the white rainbow as the droplet size becomes very small but have no intuitive understanding, for example, of a violet rainbow.

© 1997 Optical Society of America