Late afternoon rain shower, southern Gulf of Maine.
Altocumulus, contrail and iridescence all in one photo.
Near Seattle, WA
Bob Harrington, http://www.bobqat.com
Clouds formed by Kelvin Helmholtz waves in the atmosphere.
Taken 25 March 2011, this sunset was taken after a High pressure system sat on Switzerland and left so much still air that the contrails for an entire day could be seen.
Taken in Rochester, MN in July of 2010. A good summer storm was rolling through – a terrific cloud formation stretched over the downtown area looked like a dramatic moment to me. Mayo Clinic buildings seen off to the right.