This is really good but maybe add the atomic bomb sound effect at the beginning and end just to bring the devastation of it all, also maybe change a couple of words in some of your lyric lines like, "And it hit everybody" maybe "And it blew through everybody" also "Floating Away" maybe "blowing away"
Just my thoughts on this but its really good as it is.
Seen a documentary on this years back and those bombs where made to be drop on Germany but the second world war was over Germany had already surrender, i think Japan would have surrendered if that had of happen but they didn't know they had such a bomb, maybe if they did they wouldn't had to drop it at all, the madness of war but then just as well hitler didn't have one.
Sorry if all that comes across the wrong way, really good song.