On October 30, 1961, the Soviet Union conducted an atmospheric test of the 50-megaton Tsar Bomba (Russian for "Bomb King") nuclear weapon over the Novaya Zemlya archipelago in the Arctic Ocean. The ensuing detonation threw up a mushroom cloud 64 kilometers high and would've subjected anyone 100 kilometers away to third degree burns.
Even though we can cite such statistics as "the Tsar Bomba was 1,400 times more powerful than the atomic bombings of Hiroshima and Nagasaki," it's difficult to conceive just how world-smashingly large this weapon was. Designer Maximilian Bode has created this "helpful" chart delineating the destructive force of the Tsar Bomba compared to the rest of history's nuclear arsenal.
Let's all be happy that A.) the Tsar Bomba was too unwieldy for military use; and B.) the USSR didn't detonate the 100-megaton model as originally planned. For another way to visualize the Tsar Bomba, see the Nukemap.