Atomic bombs make mushroom. It's well-known and we've seen many images of atomic experiments around the world. My question is, what causes the mushroom shape? Do conventional explosives like TNT and grenades also make mini-mushrooms? Is it a physical attribute of the explosion, or something specific to nuclear energy?
It's due to the WP-Rayleigh–Taylor instability: it is an instability of an interface between two fluids of different densities, which occurs when the lighter fluid is pushing the heavier fluid.