Atomic burst over Nagasaki, coloured image. On 9th August 1945, during World War II, a US bomber dropped the Fat Man atomic bomb over Nagasaki, Japan. The atomic explosion, equivalent to 21,000 tons of TNT, generated a dense column of smoke and a mushroom cloud that rose over 18 kilometres into the air. This was the second atomic bomb used in warfare, following the atomic bomb over Hiroshima three days earlier. Over 220,000 people died in both cities, and thousands were injured. Japan surrendered a few days later. For the original version of this image, see T162/118.