Atomic bomb. A mushroom cloud of dust, water and radioactive particles produced by the test detonation of an atomic bomb at Bikini Atoll in the Pacific Marshall Islands, on July 1st, 1946 (codenamed: Able Day"). The explosion was part of a series of atom bomb tests code-named "Operation Crossroads". The photograph was taken by an automatic camera situated on an island some miles away from the blast centre and later coloured by hand.."