Take the 2-minute tour ×
Physics Stack Exchange is a question and answer site for active researchers, academics and students of physics. It's 100% free, no registration required.

Atomic bombs make mushroom. It's well-known and we've seen many images of atomic experiments around the world. My question is, why mushroom? Does TNT and Grenade also make mini-mushrooms? Is it a physical attribute of explosion, or something specific to atomic energy?


share|improve this question
It's a consequence of the dynamics of large explosions, see this video for a non-nuclear example. There is more information about fireball dynamics in this Wikipedia article. –  mmc Jul 17 '11 at 18:20
More precisely its a attibute of sudden heat evolved. An explosion with a bang is not necessary. A small pile of gun powder will burn quickly, but not "explode". Nevertheless a mushroom is formed. –  Georg Jul 17 '11 at 18:26
@Georg Yes, the heat release only needs to be fast enough to form a fireball. –  mmc Jul 17 '11 at 18:31
@mmc, why didn't you answer this question instead of commenting? Your comment was exactly what I wanted. Thanks :) –  Saeed Neamati Jul 17 '11 at 18:45
exact mmc, you should have answered. I found now that my answer did not add much on your own. But there is no need for a blast as you see in my answer. –  Helder Velez Jul 17 '11 at 21:56

1 Answer 1

Its 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.
Hot hair raises and colder goes down.
A Mushroom cloud formed by hot wet air :
enter image description here
google for images or videos of 'Rayleigh–Taylor'

share|improve this answer
Indeed the garden variety "anvil" cloud that forms over thundershower cells on the plains in another relatively low energy example. –  dmckee Jul 17 '11 at 23:38
In the recent great explosion of dynamite in Cyprus a mushroom cloud appeared, the hole was 20 meters with a 50 meter diameter as reported in the news, also that it was about 1/10 of the hiroshima bomb strength . –  anna v Jul 18 '11 at 14:43
Interestingly I just saw one of these tonight... –  David Z Jul 19 '11 at 3:50

Your Answer


By posting your answer, you agree to the privacy policy and terms of service.

Not the answer you're looking for? Browse other questions tagged or ask your own question.