Iridescence Over Sulzbach, Germany
December 01, 2006
The skies above Sulzbach, Germany on August 20, 2006 were filled with clouds and rain, however, by mid afternoon, the lower clouds departed, and I could see mid level altocumulus clouds and high level cirrus clouds in the vicinity of the Sun. I was actually looking for halos but instead was rewarded with iridescence. In most cases, this iridescence appears in thin clouds which form quite rapidly (altocumulus wave clouds, for example) and are within about 30 degrees from the Sun. The rims of many alto type clouds when near the Sun take on metallic purple, red, blue, and green colours. The coloration is caused by the diffraction of sunlight -- small water droplets composing these mid level clouds interfere with or deflect the Sun's rays. If you look for iridescent, be sure to block out the Sun, otherwise serious damage can occur to your eyes.