a. Effects of a Nuclear Attack.
Nuclear weapons cause casualties and damage to materiel through the
height of a burst, the explosive yield of the weapon, and the distance
of personnel or materiel from ground zero.
A fraction of a second after a nuclear detonation a high-pressure wave
develops and moves outward from the fireball. This is the blast wave;
it is the cause of most of the destruction accompanying a nuclear
burst. The front of the wave travels rapidly away from the fireball,
behaving like a moving wall of highly compressed air. As an example
of the speed of the blast wave, consider the following: After a lapse
of 10 seconds, when the fireball of a 1-megaton burst has attained its
maximum size, the front of the blast wave has already traveled over 5
kilometers. One effect of the blast wave is static overpressure --the
pressure in excess of the normal atmospheric pressure. As the blast
wave moves, it exerts enough pressure to crush and collapse buildings;
it can exert enough pressure on the human chest to collapse the lungs.
This effect decreases as the distance from ground zero increases. The
high-speed winds propel objects, such as tree limbs or debris, at
great speeds and turns them into potentially lethal missiles.
These winds can also physically throw unprotected individuals at great
speeds, causing casualties. Blast damage may injure individuals, both
inside and outside of a structure. It may injure individuals inside
by the collapse of the structure and fire and those outside by the
flying objects carried by the winds. As the blast wave travels
outward, it leaves in its wake a lessening of air pressure that acts
like a vacuum. This effect causes additional destructive winds that
rush back toward ground zero to fill up the vacuum.
Thermal radiation is the first effect of a nuclear burst that you can
see and feel. It is a combination of heat and light that result from
the formation of the fireball.
Within less than a millionth of a second of the detonation of a
nuclear weapon, the residues radiate great amounts of energy. This
leads to the formation of the fireball. To an observer 80 kilometers
away, the fireball of a 1-megaton weapon would appear many times more
brilliant than the sun at noon. Although the