The scientists wanted good visibility , low humidity , light winds at low altitude , and westerly winds at high altitude for the test . The best weather was predicted between July 18 and 21 , but the Potsdam Conference was due to start on July 16 and President Harry S. Truman wanted the test to be conducted before the conference began . It was therefore scheduled for July 16 , the earliest date at which the bomb components would be available
Potsdam Conference
Potsdam Conference
Trinity (nuclear test)