path would account for the failure of debris to enter the United . States on 9 November as might be expected from an extrapolation of the previous movement. It is not possible to estimate the path of this cloud toward the United States, but undoubtedly part of the material from this section of the cloud moved eastward ‘while at the same time other parts descended into the trade winds and moved back toward the west, depositing radioactivity from 24 + A ot ws ney =a Baw Hawsii to Aste 2or many days acter tue test. 1. asincts ithinths 3.3.3 ‘Stratospheric Portion The evidence provided by winds above the tropopause indicates that this part of the atomic cloud moved initially very slowly, and as shown in Figure 3.4, some layers eastward, but most of the cloud toward the west. The few wind observations at ’ these elevations suggests a zonal extension of the cloud with only small north-south excursions. Beyond this, little more concerning . _the history of the mushroom cloud can be added by the meteorologist. It is tempting to attribute the activity deposited ‘at many stations far from the Marshall Islands a few days after the explosion to transport of debris initially in the stratosphere, since there is no positive proof that the stratospheric (and mst highly radioactive) part of the cloud could not have mved in mexpected paths and at very high speeds. Such explanations have been avoided because they require wmreasonable or impossible winds. Further, most of these cases of apparent arrival of fallout which one might ascribe to the stratospheric cloud are isolated in time and space. This is contrary to that which might be expected from in the mushroom spread both to the east and to the west so if there . were any distant fallout, it would have been masked by fallout from lower levels. ; sarcatn Keats tee 3.3.4 Areas of MIKE Fallout: _' ‘Combination of the radiological with the meteorologi- cal data provides an adequate basis for estimating areas of the earthts surface that received radioactive material. Figure 3.5 shows these estimates for the first week following the MIKE test and includes areas believed to have received fallout and rainout from all levels of the clowil. That is, experience with fallout in connection with continental tests has been used as the basis for -18 - en ame TeeRRRHe fallout of debris initially in the stratosphere. The present analysis bas led to the conclusion that there is no credited report of fission products collected in this operation which positively requires transport of debris initially in the mshroom. The debris