Moonbow = Rainbow at Night
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Just after 1am in the middle of the night (returning from photographing the green sea turtles laying their eggs in the dunes) I noticed some geometrical formation in the sky on Fraser Island. I quickly stopped the car and turned off the light. It was then that I realised I am witnessing the rare event....a rainbow at night. Hurry up, get a shot or two....that's all I was thinking. Didn't even have the time to turn around the car for a Toyota promo shot...lol. It all happened so quickly.
The wind picked up and I had to use my umbrella (Mushroom in the foreground) to protect my gear from the rain drops that were already flying horizontally. Not a high quality shot that you see here but hey..consider the circumstances. Have you ever seen a full moonbow at night? I thought this was pretty special and many people probably haven't even seen a moonbow before. You can see the moon is behind me and at the bottom you see the shadow of my umbrella. The moonbow lasted only a few minutes...time enough to quickly setup the tripod, umbrella and compose this shot.
A moonbow (also known as a lunar rainbow, lunar bow or white rainbow) is a rainbow produced by the moon rather than the sun. Moonbows are relatively faint, due to the smaller amount of light from the Moon. They are always in the opposite part of the sky from the moon.
It is difficult for the human eye to discern colours in a moonbow because the light is usually too faint to excite the cone colour receptors in human eyes. As a result, they often appear to be white. However, the colours in a moonbow do appear in long exposure photographs.
A coloured circle around the moon is not a moonbow—it is usually a 22° halo produced by refraction through hexagonal ice crystals in cirrus cloud. Coloured rings close to the moon are a corona, a diffraction phenomenon produced by very small water droplets or ice crystals in clouds.
Moonbows are most easily viewed when the moon is near to full (when it is brightest). For other than those produced by waterfalls, the moon must be low in the sky (less than 42 degrees and preferably lower) and the sky must be dark. And of course there must be rain falling opposite the moon. This combination of requirements makes moonbows much more rare than rainbows produced by the sun.
Featured in Andy Frazer's Night Photography Blog