A lunar-rainbow is a rare, inspiring sight to behold; and these two moonbows, Cumberland Falls KT above and Yosemite CA below, are the only ones in America capable of generating such spectacular displays of color and light. The typical rainbow is firmly associated with sunny days and summer showers, so witnessing such a natural anomaly in the dead of night is a special, breathtaking experience.
Lunar-rainbows are frequently called whitebows due to the fact that the sunlight reflected off the moon is fainter than their more conventional counterparts. And since the human eye can only discern so much with such a faint input, lunar-rainbows often appear white. For optimum conditions, a moonbow requires a low-horizon full-moon at its brightest and an extremely dark sky. And of course, there needs to be a water-source, be it rain or mist. When rain is the cause, it is considered a true moonbow (Hawaii is a good area for moonbows).
