Cairo Cloud Corona
January 15, 2008
In early March of last year, I was in the Giza Zoo in Cairo, Egypt, photographing cattle egrets and their chicks, when these subtly but handsomely colored clouds caught my attention. On this day, the sky consisted largely of middle level, altostratus clouds, and the water droplets composing these clouds were of just the right size and uniformity to result in this lovely cloud corona. Like all coronas, the cloud corona is a diffraction phenomenon caused by the interference of sunlight or moonlight around water droplets.