This is a timelapse of passing storm clouds in Kitchener, Ontario, Canada. Taken with a Canon 40D and a 17-40mm f/4.0 L lens, ISO 400, Av Priority @ f/4; the first sequence was taken at 15 second intervals, the second sequence at 5 second intervals. I reduced the overall speed to 75% of the original 24 fps framerate. Post processing was done with Adobe Premiere Pro CS5.
For more info, check my blog: rilstone-naturephoto.blogspot.com/2010/08/approaching-storm.html
Music is "The Chase" by Kevin MacLeod.