formed over it at ks the nuclear cloud rose, a pileus of altostratus This was quickly penetrated by the nuclear cloud. ut 18,000 feet. other similar deck of cloud formed at about 33,000 feet. ati = #2 Neither of these altostratus decks persisted. 8.) eant increase in cumulus. (See Figure There was no signifi- No showers were observed except one which was 60 miles west of Bikini at H plus 5 hours and cone which was 16 miles goutheast of Eniwetok at H plus 4 hours. However, a thick persistent deck of cirrostratus cloud formed (see Figures 11, 12 and 13), and by HK plus 4 hours spread over the whole northern Marshalls. The cirro- stratus varied in density and had the ribbed appearance seen in connec- i tion with BRAVO. It persisted throughout shot day and well inte the _ following day. | A large fluctuation occurred in the 40,000-foot wind speed just H prior to the shot. At H minus 3 hours the wind velocity measured by the | USS CURTISS was 190° at 19 knots. : knots. i feet. Just prior to H Hour it was 2009 at 36 This observation was confirmed by an aircraft flying at 39,300 Three hours later the wind was 190° at 13 knots. tion cannot be attributed to the explosion. This fluctua- It does indicate, however, the magnitude of variations that occur naturally over shertintervals in the free atmosphere. | Me 455001649 a. SEs