Quite a lot actually. The atom bomb dropped on Hiroshima was an ‘airburst’ bomb, which means that it was detonated about 2000 feet above sea level to maximize damage to structures on the ground. read more
On August 6, 1945, a mushroom cloud billows into the sky about one hour after an atomic bomb was dropped by American B-29 bomber, the Enola Gay, detonating above Hiroshima, Japan. Nearly 80,000 people are believed to have been killed immediately, with possibly another 60,000 survivors dying of injuries and radiation exposure by 1950. read more
Three days after the United States dropped an atomic bomb on Hiroshima, a second atomic bomb was dropped on Nagasaki on August 9 – a 21-kiloton plutonium device known as "Fat Man.” On the day of the bombing, an estimated 263,000 were in Nagasaki, including 240,000 Japanese residents, 9,000 Japanese soldiers, and 400 prisoners of war. read more