Natural Phenomenon : Moonbow

Hello, in this time I want to tell you about natural phenomena moonbow. Moonbow is a natural phenomenon that is quite unique because usually rainbow appeared during the daytime while moonbow appears at night, which can be seen from the name "moon" moon usually appears at night. So this is the detail of moonbow. 

A moonbow in the night sky over Takayama, Gunma Prefecture, on Oct.

A moonbow (also known as a lunar rainbow, black rainbow, white rainbow, lunar bow, or space rainbow) is a rainbow produced by light reflected off the surface of the moon (as opposed to direct sunlight) refracting off of moisture laden clouds in the atmosphere. Moonbows are relatively faint, due to the smaller amount of light reflected from the surface of the moon. They are always in the opposite part of the sky from the moon.

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. As a result, they often appear to be white. However, the colors in a moonbow do appear in long exposure photographs.

Photograph of a real moonbow spanning over castle of Wernigerode, Germany

By definition, true moonbows are associated with atmospheric rain events and arise at a time when conditions are optimal in terms of levels of reflected solar light being reflected from the Moon's surface. All true moonbows are therefore short-lived and transitory in nature. True moonbows are independent of all terrestrially fixed geographical features such as waterfalls etc for their existence.

Moonbows have been mentioned at least since Aristotle's Meteorology (circa 350 BC), and also in an 1847 publication.

Moonbows are most easily viewed when the moon is at or nearest to its brightest phase full moon. For true moonbows to have the greatest prospect of appearing, the moon must be low in the sky (less than 42 degrees and preferably lower) and the night sky must be very dark. Since the sky is not completely dark on a rising/setting full moon, this means they can only be observed 2 to 3 hours before sunrise, (a time with few observers), or 2 to 3 hours after sunset. And, of course, there must be rain falling opposite the moon. This combination of requirements makes moonbows much rarer than rainbows produced by the sun. Moonbows may also be visible when rain falls during full moonrise at extreme latitudes during the winter months, when the prevalence of the hours of darkness give more opportunity for the phenomenon to be observed. One good location for viewing 'true moonbows' is Waimea 'Kamuela', Hawaii Island, Hawaii. Cause this is just a rainbow of course is not dangerous.
Source : http://en.wikipedia.org/wiki/Moonbow