power of time and meteorological arguments suggest this exponent soon increases to 2.0 to 2.5 because the rate of eddy diffusion _dncreases with time. The radioactive decay is assumed to be proportional to the 1.2 power of time. Table 6.3 is computed . under the assumption that the over-allchange is proportional- to +73:2 and shows the radioactivity expected to be collected under '.°. the core of the cloud, as a function of time. It should be _ borne in mindthat. the activity would be significantly higher in rain « perhaps a factor of ten or even 100. TABLE6.3 Estimated Meximun Dry Fallout Expected to be Collected id ae Under MIKE Trade Wind Cloud Collection Period Maxima Radioactivity Days After Burst _ “Start —_—_— 1 2 3 Neate h : S° i | Expected Without Rain End . d/m/ft?/day 2 3 b x 10° | 6x10" 5 7x10°) k 6 12 2x10 kx 10° 3x 10° Range Estimated to Include Approximately ' 50% Likelihood gf Occur- rence d/m/ft</day = 108to 107 2x20" to 108 © 5 x 210° x 107 2=—Sti<‘<it~‘*«Sdto _ x 0" No range ~- an absolute Value by assumption. ‘tot to 10° The last item of the table is shown for comparison with the greatest radioactivity measured wi entered the United States, name 104 at Boise, Idaho. this portion of the cloud d/m collected 11 to 12 November : sO It should be noted that the computation has ‘not been extended ceed Std ‘eltahanal ni -to the first day after burst because it is probably invalidated by the fallout of large particles. 6.6 _ ASSISTANCE 0 METEOROLOGY In view of the paucity of weather data aud the lack of an adequate knowledge of tropical meteorology and turbulent diffusion, it might be expected that the use of atomic debris as a tracer would 2 53