I've been trying to read up and understand why a air burst of a nuclear weapon is less catastrophic than a ground burst when speaking about nuclear fallout. I think I understand that intensity of the dangerous radiation falls off quickly because of an inverse square law, but what happens to the rest of the radioactive material (energy)? it just floats away? the atmosphere just eats it up? if a nuclear weapon explodes when hitting the ground, is the dangerous radiation now embedded in the ground and that is why the fallout of a ground burst is worse? thanks.