Why Do Bombs Create Mushroom Clouds?
| Updated: 10 Feb 2026
What makes the explosion from a bomb look like a mushroom?
Question:
Why do atomic explosions create mushroom clouds?
Tim, Clapham
Answer:
**DEFINITIVE**
Name: Professor Hal
Qualification: Professor of the Public Understanding of Science at the University of Brighton, with a cub-scout badge in science
Answer: if it’s a hydrogen bomb, it reaches a temperature of 100 million degrees at ground level. So hot air rises, and the stalk of the mushroom is the hot air rising, carrying with it the debris and igneous rock. At some point, the density of the air gets thinner, and the air that has been rising reaches the same density as the air around it, so it starts flapping out, so that’s where the cap of the mushroom comes.