0 an arch (= curved shape) of white light seen in the sky when rain is falling and the moon is shining
At full moon, a moonbow can be seen in the spray instead of the usual daylight rainbow.
The falls are one of the few places in the western hemisphere where a moonbow can frequently be seen on nights with a full moon.
Under a full moon on clear nights, an elusive lunar rainbow or moonbow is sometimes formed by the mist emanating from the falls.
Because the light is usually too faint to excite the cone color receptors in human eyes, it is difficult for the human eye to discern colors in a moonbow.
