National Geographic : 1946 Feb
1. S . Army Air Forces, Oficial Debris, Dust, and Vapor Rush Heavenward as the Atom Bomb Bursts over Nagasaki A fiery explosion "too tremendous to believe" was reported by American aerial eyewitnesses of the B-29 attack on August 9, 1945. The detonation sent up a column of debris and dust topped by a cloud of white vapor boiling to 45,000 feet. The heart of the city was transformed into a desert and at least 40,000 were killed.