The site Extreme Instability is the photographic diary of a professional storm chaser.
As a proud, card-carrying member of The Cloud Appreciation Society, I marvel at what he's captured. The above image is taken from a recent series he shot of a supercell storm above Bucklin, Kansas, U.S.
The site features video and a moment-to-moment journal of his many storm-chasing experiences. This guy has gotten quite close to a multitude of tornadoes — if you've never experienced one first-hand, the site's images and stories will replicate how terrifying it is for you.
UPDATE: Mike Hollingshead of Extreme Instability is working on a book with another storm chaser. Mike states: "It should be out by mid-summer (wild guess). It's mostly just a photography book, with some text. It's through Thames and Hudson in London."