User Guide

Electromagnetic Pulse (EMP). A nuclear explosion gives off
radiation at all wavelengths of light. Some is in the radio/radar por-
tion of the spectrum - the EMP effect. The EMP effect increases the
higher you go into the atmosphere. High altitude explosions can
knock out electronics by inducing a current surge in closed circuit
metallic objects - electronics, power lines, phone lines, TVs, radios,
etc. The damage range can be over 1000km.
OVERVIEW OF IMMEDIATE EFFECTS
The three categories of immediate effects are: blast, thermal
radiation (heat), and prompt ionizing or nuclear radiation. Their rel-
ative importance varies with the yield of the bomb. At low yields, all
three can be significant sources of injury. With an explosive yield of
about 2.5 kilotons (kT), the three effects are roughly equal. All are
capable of inflicting fatal injuries at a range of 1km.
The fraction of a bomb's yield emitted as thermal radiation,
blast, and ionizing radiation is essentially constant for all yields, but
the way the different forms of energy interact with air and target
vary dramatically.
Air is essentially transparent to thermal radiation. The thermal
radiation affects exposed surfaces, producing damage by rapid heat-
ing. A bomb that is 100 times larger can produce equal thermal radi-
ation intensities over areas 100 times larger. The area of an (imagi-
nary) sphere centered on the explosion increases with the square of
the radius. Thus the destructive radius increases with the square
root of the yield (this is the familiar inverse square law of electro-
magnetic radiation). Actually the rate of increase is somewhat less,
partly due to the fact that larger bombs emit heat more slowly which
reduces the damage produced by each calorie of heat. It is important
to note that the area subjected to damage by thermal radiation
increases almost linearly with yield.
Blast effect is a volume effect. The blast wave deposits energy in
the material it passes through, including air. When the blast wave
passes through solid material, the energy left behind causes damage.
When it passes through air it simply grows weaker. The more matter
the energy travels through, the smaller the effect. The amount of
matter increases with the volume of the imaginary sphere centered
on the explosion. Blast effects thus scale with the inverse cube law
which relates radius to volume.
The intensity of nuclear radiation decreases with the inverse
square law like thermal radiation. However nuclear radiation is also
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