Before revision: In many cases, when the droplets are very small, fog bows appear white, and are therefore sometimes called white rainbows.
After revision: The colors fade due to being smeared out by the diffraction effect of the smaller droplets.APOD: 2006 November 15 - A Fog Bow Over CaliforniaIn many cases, when the droplets are very small, fog bows appear white, and are therefore sometimes called white rainbows.