Original source (now obsolete): Source:
http://www.istartedsomething.com/bingimages/#20110122-us,
http://www.istartedsomething.com/bingimages/cache/SupercellThunderstorm_EN-US4078968379.jpg
Source: “A supercell thunderstorm rolls across the Montana praire at sunset” – Sean Heavey © (Bing United States)