I took this photo of a double rainbow over St. Bede’s yesterday, a treat for those still around to see it. The second rainbow’s colors are reversed, look carefully, and the light under the brightest rainbow is brighter than above. A double rainbow is caused by a double reflection of the light within a drop. Light can reflect many times inside a drop of water, though our eyes rarely see more than two if, like yesterday, we are lucky. The light band underneath is caused by the fact that all the light that is bent to make the rainbow can continue to bend more, but can’t bend any less- ie. there is more light under a rainbow than above it. The dark band between the two rainbows is called Alexander’s Dark Band after Alexander of Aphrodisias who discussed the phenomenon around 1800 years ago!
Wishing you all the brightness under the rainbow. Happy Valentine’s Day!