BRAVO EVENT The device was detonated at 0645 hours local (mM), 1 March (CHARLIE) at Bikini. Yield was approximately 15 megatons. A trade wind type weather situation typified the Marshall Island weather on 1 March 1954. low as 7,000 feet. bE Ce 1954 as a land surface shot on a small sand spit near NAMU Island Winds with westerly components occurred as Ordinarily such winds are not present below 15,000 to 25,000 feet. 4/8 cumulus, bases 2,000 feet, tops 4,000 feet; few altostratus (1/8) at about 18,000 feet; and 6/8 very thin cirrostratus were observed at shot time. (See Figures 4 and 5.) ‘No showers were discernible. As the fireball rose and the nuclear cloud developed, a series of pileus There was a altocumulus and altostratus were seen to form near the explosion. Despite the marked westerly component of the winds at the levels where the aitocumulus were observed, the clouds progressively increased to 3/8 to 4/8 coverage for a brief period at about H plus 3 hours. Cloud formed fron the mushroom and spread siowly. leading edge had reached Eniwetok. A great cirriform By H plus 5 hours the This cloud had the appearance of Cirrocumulus intersticed with many long filaments which appeared from the 6 titer war at OO tees in ee oe At Eniwetok, 180 miles to the west, small segregated patches of 4:0 before or immediately after the shot. = There was no definite evidence that showers occurred either oe errr oe Figure 6.) (See fi brief increase in cumulus, both in amount and height of tops. omer em ek ee a es ey clouds developed and were penetrated by the rising stem.