Tsar Bomba mushroom cloud
The mushroom cloud of Tsar Bomba, the largest nuclear weapon ever detonated, with a yield of approximately 60 megatons.
The cloud reached nearly 64 kilometers into the sky.
You want more detail than that, YOU go and read the damn Wikipedia page.
I'm uploading this because I think the image is amazing, and these types of things have a habit of appearing and disappearing on the internets.