How does a Mushroom Cloud Form

What’s the science behind these oddly shaped clouds?

Mushroom clouds are usually the result of a colossal explosion, such as that produced from a nuclear weapon or another type of large explosive device. Mushroom clouds can tower many miles in the sky, but they will flatten out around the stratosphere, hence how they acquired their name.

When an atom bomb is dropped, it doesn’t explode on the ground. Instead, it’s detonated several hundred metres above land to maximize the blast impact. This creates a fireball of superhot gases in the air within a split second of the explosion that can be several miles wide. This intensely hot ball draws up debris from the ground as the air pressure inside is much lower than that outside.

The ball of fire rises upwards as the head of the mushroom cloud, carrying a column of dust and debris in its wake. It eventually reaches a point where the air is thinner – the stratosphere – causing the head to flatten out.

The fire spreads out in all directions and convection currents form inside the head. These currents force the edges of the head to curl downwards and rejoin the central column, giving the appearance of a traditional toadstool or mushroom.

Mushroom clouds generally only form as the consequence of a large manmade or natural explosion, such as a volcanic eruption, however they have been recorded to occur in much smaller explosions on Earth too, such as after the firing of a cannon, fn the case of a volcanic eruption, the enormous amount of heat created at the peak of the volcano takes the place of the fireball in the atom bomb scenario.