APOD #3, for the week of 9/10-9/14 (I was absent, sorry it's so late)

APOD for September 12, 2007
This picture is of a triple rainbow, reflected by a calm lake and therefore producing an image of six rainbows. While it's more common to see a double rainbow, even that is rare and the triple rainbow is hard to explain. The normal rainbow is created by internal reflection and refraction by the air around the rain drops as they fall, and the second rainbow is caused by multiple internal reflections. According to one of the links, the third rainbow (a reflection bow), which appears at such a different angle than the other two which seem almost parrallel, is caused by the light reflecting from the lake and then being refracted and reflected by the rain. The picture was taken in Sandessjøen, Norway after heavy rain storms.