Nuclear Blast Damage

Blast damage from a nuclear weapon comes from the overpressure in the air and from winds which result from the pressures. For a 10 kiloton blast at the height where it would produce the most damage, severe damage to frame houses would occur out to 1.6 km and moderate damage to 2.4 km. For a 10 megaton blast, 1000 times as powerful, the severe damage would extend out about ten times as far, to 17.7 km. (Figures from Microsoft Encarta). A 10 kiloton blast would produce a fireball of about 300 m diameter and would cause moderate flash burns (second degree) at a range of about 2.4 km. A 10 megaton blash would create a fireball about 4.8 km and moderate flash burns to 32 km. Accompanying the blast is a burst of neutrons and gamma rays, as well as lingering residual radiation from radioactive fallout.

Radioactive Fallout

In addition to the great destructive power of fission bombs, the highly radioactive fission byproducts are released into the atmosphere and spread over a wide area. Radioactive fallout in the form of fine particulate matter is particularly dangerous because it can be ingested, bringing alpha and beta emitters into the body where they can do much more damage. One of the most serious components of the fallout from weapons testing in the deserts of Arizona and Utah was strontium-90.

A Ton of TNT

For some reason, the comparison unit for nuclear explosions which became most popular was the "ton of TNT". A nominal energy release for a ton of TNT can be extracted from general statements about nuclear weapons. One of those is "one kilogram of mass converted to energy is equivalent to about 22 megatons of TNT". From the Einstein equation, the conversion is

This is consistent with the oft-quoted statement that the 20 kiloton Hiroshima bomb converted about 1 gram of mass to energy.

Nuclear Winter

Riddle: What has a dust storm on Mars have to do with the nuclear arms race?

Answer: A massive dust storm on Mars, observed by the Mariner 9 spacecraft, obscured the surface for weeks and dramatically lowered the surface temperature under the dust cloud.

This was perhaps the first clear evidence that a major nuclear weapon exchange could have catastrophic global climatic effects. Air bursts tend to blow fine particulate matter high into the atmosphere where it could stay for months or years. The term "Nuclear Winter" was introduced by the TTAPS group to describe the cold and dark which would accompany this high particulate cloud.