Sky Diary 20 May 2013 Duncan, Oklahoma tornado - 2013-05-20 at 15-42-29

Caption: Separated from my chase partners, I dropped down the line of storms and saw these mammatus clouds. Photo by Chris Kridler, SkyDiary.com, ChrisKridler.com
Aperture: ƒ/10
Shutter Speed: 1/320
Date: 5/20/13 3:42:29 PM CDT