U.S. WEATHER BUREAU PHOTO
FIGURE 2.—Generalized drawing of the earth’s atmosphere.
ceeeaeOE etacet cee ees
regions and one year or somewhatless at the equator. Radioactive debris from nuclear detonations occurring at very high
altitudes (about 30 miles and higher) may have a residence
half-time of five years or more.
Roughly two-thirds of the radioactive particulate debris
injected into the lower stratosphere at the north polar regions
has been observed to fall in the 30°-60° North latitude zone,
where about 80 percent of the world’s population live. Injection at the equatorial regions has been observed to result in
a more even distribution between the two hemispheres.
For surface bursts of high (million ton range) yield about
50-80 percent of the radioactive debris is deposited as “early
fallout,” ie., within 24 hours. Air bursts—wherethe fireball
does not approach the surface — result in little, if any, localfallout.
Table 2 tabulates some of the key data on estimated nuclear
energyyields from all past nuclear weapons tests. Of the total
energy released of 511 million tons equivalent of TNT about 70
TABLE 2.—Estimates of Yields from All Nuclear Weapons Tests
Total million tons*.....0...0.0 ccc cceceeeatueeeeeens
Fission million tons..........0.0.0..cc.cccecceecccueaeeeeeceueeas
Fission million tons scattered globally...........00000....
USSR
US and UK
Totalt
350
141
110
161
82
51
511
193
161
*TNT equivalent.
+The French tests have contributed only smali amounts.
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