Probably the first characteristic that immediately comes to mind regarding the effects of nuclear war is the surging clouds of smoke and debris that quickly rise up to thousands of feet in the atmosphere after a nuclear blast. The majority of people would recognize a nuclear explosion solely as a result of seeing this distinctive “mushroom cloud” reaching far above the earth. These plumes of smoke are formed through blast excavation of soil and earth at the point of detonation in addition to the pulverization of buildings, plants, and other structures on the ground. The initial nuclear fireball creates a region of super-heated air having low density, which because of its extreme buoyant mass creates a region of turbulence that rapidly rises into the atmosphere. These turbulent vortices form the upper mushroom part of the cloud, which has the characteristic of ballooning outward with bellows of smoke and debris curling downward at its outer edges as it rises upward. In addition, the strong updraft from the ascending fireball creates an internal suction, causing cooler air to quickly move in from all surrounding directions at velocities that can exceed hurricane-strength winds, which then rise within a central column of ash and smoke. In fact, the largest nuclear weapons can produce updraft winds within the central column that are in the range of 600-800 miles per hour. This upward flow rapidly forms the stem of the mushroom cloud, and its thickness and ultimate height are indicative of the size of the nuclear explosion. Within seconds the mushroom cloud can rise above the typical cumulus cloud height and after about 10 minutes it can extend up into the stratosphere with a tremendous ascending flow pulling the smaller particles of debris, soot, smoke, and ash along with it. Thus, the full mushroom cloud effect of a nuclear blast typically takes only moments to form from a ground burst or a near-ground explosion, but can create a massive column of smoke extending from the surface even up into the stratosphere.
The major component of these mushroom clouds is smoke. Smoke can be formed from the combustion of any flammable organic materials (carbon based), and it becomes sootier as the temperature of combustion increases. In the center of a nuclear explosion, the temperatures are far greater than typical fires or explosions. At a temperature of millions of degrees within the fireball, any flammable items will be instantly transformed into tiny particles of soot. These particles are largely made up of amorphous elemental carbon with sizes in the range of nanometers to micrometers in size (from: Environmental Consequences of Nuclear War Volume I: Physical and Atmospheric Effects, Ch. 3, p. 40). At this size, they can easily be carried upward with the rising fireball.
In addition, the closer the blast is to the Earth’s surface the more dirt and debris can be carried up by the inflow and up-flow of winds. A ground blast will often carve out a massive crater and cause strong inflowing winds that can pick up the pulverized debris from miles around and form a thick dark column leading up to the ascending fireball. The final height of the pillar of smoke is dependent on the yield of the nuclear explosion and the prevailing winds in the atmosphere. For weapons of about 1 MT yield exploding near the surface, the mushroom cloud top can reach over 12 miles high. For the largest thermonuclear fusion bombs tested, the cloud can actually reach over 25 miles high, which is about 4 times the cruising altitude of a typical passenger jet. Thus, one of the initial effects of nuclear war are the giant columns of smoke emanating from each blast…[read entire article]