Mushroom. Atomic Cannon. http://video.google.com/videoplay?docid=252288483406479718# Caption: Atomic Cannon detonated at the Nevada Test Site in 1953, showing a-bomb or atom bomb detonation and weapon effects. Exploded with a force of 15 kilotons. Sequence from "Trinity and Beyond - The Atomic Bomb Movie" (1:17 min)