WRAL WeatherCenter Blog

Artful Diffraction

Posted January 27, 2009 7:17 a.m. EST

Sometimes the whole purpose of a post here is to share an especially nice photo that we ran across somewhere, especially if it also illustrates an interesting phenomenon (in this case two) occurring in the atmosphere.

The photo you see here was posted on SpaceWeather.com  about a week ago, and was taken by a photographer named Harold Leinbach, who tells me that this was one of those fairly rare cases where a beautiful phenomena actually showed up more clearly in the processed digital image than it appeared to the naked eye, due to the brightness of the scene. Toning that brightness down a little in the image made clear the iridescent colors in a series of "lee wave" clouds being generated downwind of the Rocky Mountains. The photo captures nicely both the pastel colors of the iridescence phenomenon (resulting from diffraction of sunlight by small cloud droplets of relatively uniform size) and the eye-pleasing structure of the wave clouds, associated with winds flowing across rugged terrain when a layer of stable and appropriately moist air is present.

There's a nice discussion of the photo on the SpaceWeather page where it appeared. I added a link to that and also a couple of others with more background on wave clouds and iridescence. Enjoy! Incidentally, in our area a good place to look for iridescence on occasion is around the fringes of the anvil of a thunderstorm or in the smooth "pileus" cloud that sometimes forms above the thunderhead...