Iridescence from Super Moonlight
July 15, 2013
Photographer: Ronald Smith
Summary Author: Ronald Smith
Sometimes, waking up early produces unexpected dividends. In the wee morning hours of June 24, I was able to capture the lenticular cloud iridescence shown above from the Sunriver Golf Course in St. George, Utah. Just one day past the “super moon”, moonlight illuminated this double-convex mid-level cloud (lenticularis). Because lenticular clouds are composed of tiny water droplets, iridescence is sometimes observed about their edges. Iridescence or irisation is a diffraction phenomenon. Light, in this case moonlight, is deflected by similar-sized droplets. Minute differences in the shape or size of the droplets can result in remarkable differences in brightness and color intensity. Note the "milk dipper" of Sagittarius just below the colorful cloud.
Photo details: D3200 Nikon camera; 1/2 sec. exposure; f/5.6; ISO 400; 23mm lens with a Nikkor 18-55 zoom.