Chapter 6 SUPPLEMENTARY MEASUREMENTS On detonations of the magnitude of the Castle shots, several phenomena occur which, oan smaller shots, either de not appear or are extremely short-lived. Hence, it is desirable to report here other measurements in addition to the height and diameter of the main cloud. "Skirts, " "hells, " condensation rings, thunderheads, ice caps, and the stem have been measured wherever they appear. Their diameters and heights have been calculated in the same manner as the dimensions of the main cloud. Figure 6.1 is an idealized sketch of a nuclear cloud in the megaton range, showing the nomenclature employed in this chapter. Films from K-170 and Eclair cameras located in aircraft have been utilized for the purposeof obtaining the supplementary measurements, since most of these secondary ' -phenomena occur at later times than are covered by the high-speed, ground-based cameras. 6.1 SHOT 1 The cloud, at various stages in its development, showed four condensation rings, three ice caps, two skirts, and three bells. Figure 6.2, taken at 45 seconds, shows the condensation rings and two of the ice caps. Figure 6.3 is a plot.of the diametersof all the measurable phenomena and Figure 6.4 gives their heights with respect to sea level. No reliable data can be obtained on heights of the bells. The four films measured for stem diameter showed good agreement through ten minutes. Unfortunately, it was not possible to measure the diameters of the four con- densation rings, as all the aircraft were located too close to ground zero. Data from two Eclair films did, however, permit determination of these heights through -25 minutes. Diameters of skirts and bells were measured from onefilm each. In both cases, the dia~ meter measured is that of the widest portion; e.g., for a skirt the diameter measured is that of the base of the skirt. Three films gave good data on diameters of two ice caps. The height curves are based on only one film, however, since the other two films yielded poor data. Only one filmshowedthe third ice cap; hence, the resulting calculations vield only estimated figures, Betwcon 1.0 and 1.6 minutes the diameter of the third ice cap increased from 45 to 65 thousand feet; in the same time range, the height to bottom was between 20 and 25 thousand feet. 6.2 SHOT 2 . Figure 6.5 shows the diameter and height of the five skirts visible during this shot. Because of the particular arrangementof the skirts, it appeared that the two upper skirts had a common base, as did the two lower skirts, although it was possible to measure distinctly separate diameters for all five. bells, and a portion of one other skirt. Figure 6.4 shows the upper two skirts, the two Two condensation rings were visible, the maximum 28 SECRET 5 maine a meaniaaa MTNNNR EN ae wee oe ete