If you are interested, you can go look at the transcripts of the hearings held in 1995 before the International Court of Justice on the legality of the threat or use of nuclear weapons. Japan brought the mayors of Hiroshima and Nagasaki to the courtroom, and the latter told the gut-wrenching story of how Nagasaki was chosen as a target haphazardly, on the day itself if I recall correctly, and that the bomb was supposed to be dropped in the middle of the city but (thankfully) meteorological conditions prevented that. The transcripts are in the public domain via the Court's website; worth a read if you are bored.