system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: How do nuclear bombs manage to cause so much damage on the ground when most of their energy appears to be wasted in the upward travelling fireball / mushroom cloud?

So obviously the primary immediate physical damage (not counting radiation, actual blast damage) of a nuclear weapon is caused by the shockwave rippling out from the explosion and essentially flattening or severely damaging anything in its path. But aren't nuclear bombs actually very inefficient with their energy? The vast majority of it appears (from footage) to be lost in an upward travelling fireball, and you can see rings form around said fireball *in the air* where further shockwaves are spreading out.

Such a damage profile would seem to actually be far more damaging to anything in the air *above* the explosion than anything on the ground around it, but obviously we know that this is not the case.

So how is it that they cause so much ground level destruction even though, at first glance, it would appear that most of their energy goes into creating the airborne explosion as opposed to the ground-level shockwaves?
gpt
Imagine a bomb exploded in the air with no land anywhere around it. The force would expand out in every direction equally. When a bomb explodes on the ground, as much force goes down as does up. Most of this force down gets pushed sideways because the land blocks it from going down. This causes massive waves of energy that travel sideways along the ground after the initial shockwave.