Originally Posted by
SOPS
I don’t understand why they describe it as a ‘clean bomb’. WTF is ‘clean’ about it? It was polished before the exploded it?
To be a 'clean' bomb, it had to be an 'airburst' ie detonate sufficiently high so as not to suck up debris from the surface into the fireball which would subsequently come back down as radioactive fallout; by detonating above the ground, you also get maximum damage from the shockwave too.
At least, that's what we were taught in the Royal Observer Corps where we had to report the fireballs as 'touching' or 'clear' from our GZI photos.