Question: why is the shape of a nuclear explosion so significant?

Megan Seymour answered on 9 Nov 2016:

I think you’re talking about the ‘mushroom’ shaped cloud that is often pictured when we see images of what a nuclear explosion looks like?

The cloud is mostly made up of smoke and steam and is actually a common shape for the cloud resulting from any explosion that produces enough energy, not just a nuclear one- some massive volcanic explosions for example would produce the mushroom shaped cloud of gas.

The mushroom shape forms when large amounts of a lighter gas (for example hydrogen) is formed. The lighter gas rises up very quickly creating the stem of the mushroom, and the heavier gas (for example oxygen) that it pushes out of the way forms the top of the mushroom.