Last Saturday, June 26th, after a summer evening thunderstorm, a bank of spectacular mammatus clouds formed over Manhattan," reports Snehal Patel of New York. "It was an amazing display that looked like large orange cotton balls falling from the sky."
He took this picture using an iPhone 3G:

Mammatus clouds, named for their resemblance to a cow's underbelly, sometimes appear at the end of severe thunderstorms when the thundercloud is breaking up. Researchers have called them an "intriguing enigma," because no one knows exactly how and why they form. The clouds are fairly common but often go unnoticed because potential observers have been chased indoors by the rain. If you are one of them, dash outside when the downpour stops; you could witness a beautiful mystery in the sky.

Posted: 11:36:26 AM  
link to this article: http://www.marinasmasters.com/2006/categories/articles/2009/06/29.html#a6808