(er at ~ ab SECRE This means gghat 4% 104 particles of 0,3 micron diameter from the surface and 3 X 1022 particles from the uncerground shot will reach the stratosphere. It has been assumed that 1.5 X 1020 particles of 0.3 micron size are required to reduce solar radiation by 10 to 20%. Even if this assumption is in error by a factor of 10 or even by a factor of 100, superweapons of 10 to 100 megatons still haw the capability of reducing solar radiation significantly if exploded on .e surface or underground. If superweapons are exploded in the air instead of on the surface or sub-surface, they will have no effect on the climate of the world as far as the dust factor is concerned. It is also assumed that the atomic cloud will rise up to heights of 70,000 to 100,000 ft. V. MeSole SUMMARY AND CONCLUSIONS : A. It 4s assumed that if approximately 2 X 1024 to 2 X 1026 volcanic ash particles of 2 micron diameter are distributed in the isothermal region of the atmosphere, solar radiation will be reduced by 10 to 20%. If the atmosphere is filled with such an amount of volcanic ash once every year or even once every two years over a long period of time, the surface tempera~ ture of the earth may be reduced by several degrees resulting in a general cooling of the hemiaphere, B. It is calculated that if superweapons of 10 to 100 megaton energy yield are exploded on the surface or underground in cry clay or sandy type of soil, a sufficient amount of 0.3 micron soil particles will be ejected into the isothermal region of the atmosphere to reduce the solar radiation by appror sate .y 10 or 20%. If such superweapons are exploded once every six month. over a period of time, it may be possible to reduce the surface temperature sufficiently to depress the snow line and to increase the general cloudiness. Thus it may be possible that a general cooling of the climate of the Northern Hemisphere is within the reach of man. C. Since it is not possible at the present time to compare the soil of Eniwetok with that at Nevada Proving Ground or at Dugway, no statements can be made concerning the effect of superweapons exploded on the surface in the Pacific Islands. D. If it is at all possible to lower the surface temperature of the earth, thus bringing on a gereral cooling, this effect probably cannot be confined to any one region or country. E. It will be difficult to evaluate experimentally the amount of dust thrown out into the stratosphere from superweapons exploded on the surface or underground, This is because sample collecting methods at heights of 100,000 ft. have not yet been developed, and also because of the low order of collection efficiency for particles which have diameters less than one micron. However, it may be possible to make some indirect measurements. For instance, a change in sky brightness or a reduction in the solar radiation may be anticipated, mapa neh T tt “ wat bid edly OTe ks C2=22190