A feature analogous to the rainbow, but caused by moon light. The moonbow is best seen from halfway up the summit Mauna Kea, Hawaii, or other similar sites, and is usually white due to the faintness of the moon. However, on exceptional occasions, the rainbow color can be seen. (I have seen a color moonbow only once in my life, and that was on Mauna Kea, Hawaii.)
Although I have not personally seen one there, I am told that moonbows can be seen at the base of Yosemite falls under good conditions, as well as at Cumberland Falls State Park in southeast Kentucky.