The Atomic Bomb- What happens in a Nuclear Explosion

Immediate Effects on an Urban Center

from a 20 Megaton Bomb Detonation


Ground Zero

  • Within one hundredth of a second, a fireball would envelope
everything within two miles.

  • Temperatures rise to 20 million degrees Fahrenheit
(comparable to the inside of the sun) during the detonation,
cooling rapidly as the fireball forms. After a minute, no
significant amount of heat is given off.
  • Everything at ground zero is vaporized

2-4 miles from ground zero

  • Air pressure reaches 25 psi and wind speed reaches 650 mph.

  • Steel-framed buildings and steel-reinforced concrete buildings
are torn apart and leveled.

4-10 miles from ground zero

  • The heat would still be high enough to vaporize sheet metal
found in cars and melt glass.

  • Winds reach speeds of up to 200 mph, leveling brick and cinder
block structures as well as structures with wooden frames.

16 miles from ground zero

  • The heat would be high enough to ignite easily combustible
materials such as houses, wood, trees, cloth, gasoline, and
heating fuel. This would trigger hundreds of thousands of

  • Winds reach speeds of over 100 mph and reach 2 psi,
still enough to shatter windows, cause damage to most houses
and buildings, and knock a person off their feet.

29 miles from ground zero

  • Heat still reaches temperatures that will cause third degree
burns on any exposed skin.

  • Wind speeds as a result of the explosion are negligible.

Up to 40 miles away from ground zero

  • Flash blindness may be caused by anyone looking in the
direction of the explosion.

  • Permanent blindness may occur to anyone looking directly at
the explosion if the light is focused through the eye’s lens in
a way which causes burning of the retinas.