October 19th, 2010
The biggest surprise for me in seeing this chart of Earth's Atmosphere Top to Bottom was right at the bottom. I always knew that the mushroom cloud from an atomic bomb explosion reached high into the atmosphere – who hasn't seen the film of the mushroom cloud expanding upwards as well as outwards? – but somehow I'd never quite made the connection that this implied that the blast wave from even a relatively puny 1 megaton explosion would tower over Mount Everest.
Seeing it depicted graphically like this was oddly shocking.
[Via Bad Astronomy]