baveredet During the warmer half of the year, precipitating clouds build up into the high troposphere only infrequently. The Kona storm is a rare phenomenon in the warmer seasons and shower clouds would reach into the high troposphere on the average of little more than once a month during the months April through : October. “A rough estimate of the maximum radioactivity that . would be scavenged under the optimal conditions might be made by use of the large rainout at Albany and Troy, N. Y., on 26 April ' 1953 during the UPSHOT-KNOTWOLE test series (i af 52). It was J reported that Albany received about 15,000,000 d/m on a day during ' which a thunderstorm penetrated a fresh atomic cloud. Troy was monitored and found to have received a dose of 0.1 roentgen. integrated over thirteen weeks. If one merely scales up these figures by the ratio of the yields, then the Hawpeiien Islands might receive a peak activity of the order of 10° d/m or a thir- | teen week integrated dose of 10 roentgens. - In summary, it appears that under typical weather conditions, the Hawaiian Islands would receive fallout and rainout of the same order as observed during IVY if the total amunt of radioactivity initially in the high troposphere were similar to that of MIKE and KING. It should be recognized, however, that a potential hazard exists both from the standpoint of anamolous weather patterns and from the fact that a different. type test Say an underwater burst - might stabilize greater quantities of - debris in the high troposphere. Considerably more study would be required to determine the probability of the maximum rainout | and the possibility of utilizing meteorological forecasts to avoid this situation. | 5. THEUNITED STATES _ The highest radioactivity collected on gummed papers and air filters during Operation IVY were much lower than during tests at the Nevada Froving Ground. The IVY clouds were not particularly fast-moving so it is not surprising that the great distance and time involved overcompensated the tremendous yield of MIKE, The peak air conegatration recorded was 3 a/m/m? and most of or less. Because so few stations obtained air filter data and because so little correlation between gummed the values were 1 d/m/ paper and air filters can be found, no snalysis of this data is attempted. . - 36-