+a , ” ama cloud during early times after burst except for a brief period when the banb light shown diffusely through the cloud cover. A graphic view of the veather formations from an altitude af about 15,000 feet (absolute) between H+1 and H+5 minutes can be obtained from Figso 11.2-1 thru 11.2-) (pictures and data were furnished by Project 9.1). As is shown in Fig. 11.2-h, contrast between the bomb cloud and the ‘natural clonods is becoming extremely poor. Consolidation of the space between cloud layers from growth of the moisture rings and the rise of the cumlus layer, together with the high moisture content of the bomb cloud, made it extremely difficult to distinguish bomb cloud from natural weather cloud at later times. , ~ The situation was alse complicated by rapid dispersion of the tomb cloudbecause of a very unfavorable wind- sheer structure. illustrative a} FOYY aad mission is reported in some detail below as of the difficulties of successfully conducting a sampling nission under "all-weather" conditions. As daylight illumination increased, the extent and opaqueness of the Cirrus layer within which the director aircraft was flying became apparent, An attempt was made by interrogation of other aircraft in the vicinity to find a location from which visual contact with the cloud could be made. This attempt was in some degree successful in that at about Ht+60 minutes, the director aircraft {now at 45,000 feet (atsolute)) found a hazy hole in the cirrus cover to the east of zero point. By looking down and to the north through this hole, heavy white clouds could be seen which cast &@ shadow of brown transmitted light on lower cumulus heads. Eecause of the heavy weight of the director aircraft which required a long orbit