Master 1490 - Tape 1 Various views of Snapper atomic event conducted at Nevada proving grounds during Operation Tumbler-Snapper, 1952. Gorgeous dusky colors, the events occuring during dawn or dusk. Aerial of massive 20 kiloton atomic explosion that begins with a blinding flash. Level LS 20 kt atomic blast. WLS 20 kiloton atomic bomb blast, night. Aerials of mushroom cloud, including downright evil-looking TLSs roiling, shifting mushroom cloud.