[Someguywhatever]

I don't think that the effects of the bomb were as well understood as we imagine, I think that unleashing the bomb on Japan was also a test. It was targeted at civilians and they just HAD to see what it would do, they knew that what it would do was going to be bad, but they didn't really know how bad. IMO they didn't really care how unpredictable or targeted it would be, they knew it would affect Japan only though, so thats all that mattered.