Tha eastward moving debris reached the Americas on March 7 and 8, indicating an average west wind of about hO knots, in good agreement with the few wind observations available in the upper troposphere. Although the progression of debris to the west appears to be in good agreement with the $,000-foot trajectory, indicating that the transport occurred in the trade wind layers, it is entirely possible that stratospheric debris moving with the upper level easterlies contributed te this fallout also. The most striking fact which emerges from a study of the fallout in the period following the Bravo test is the tendency for the debris to remain in the tropical latitudes. By far the largest amounts of fallout occurred in the latitude band from 10°S to 20°N, with occasional excursions into the more temperate latitudes of each hemisphere, particularly in the Americas. An example of this can be seen in the southwestern United States in the period beginning March 15. At this time, a deeo low pressure system extending through most of the troposchere was located just off the west coast, with strong southwesterly winds over the southwestern states. This derression moved slowly eastward so that by March 18th, the southwesterly winds were over the “ississiopi Valley. An examination of the fallout maps reveals that fallout during this period was associated with the southwesterly winds, which carried debris from the tropical regions. It is significant that this fallout was independent of vrecinitation. The highest fallout values occurred during the first three days of the period when there was no precipitation, and even on the 18th, when there were several stations renorting precipitation, the fallout occurred _in the region dominated by the southwesterly winds and was not closely associated with the existence of preciritation. A somewhat —— similar series of events occurred in the period March 21-25, although precipitation was more widespread.4n this case and may have had more influence on the observed fallout patterns. . 2.2 AU. The second burst of the Castle series, Zomeo, from @barge at 1830 GCT, March 26, 195) was detonated The wind observations associated witn tnis burst showed light easterly winds at virtually all levels increasing in speed above 80,000 feet to a maximim of 92 knots from the SE at the top of the highest observation, 95,000 feet. Although the trajectorle. (Figure: 2.3) at all levels in.the-troposphere moved westward initially, the 30,000- and h0,000-foot trajectories curved northward -9-