wean —_ Project 11.2 - CLOUD SAMPLING (H. Plank) Aircraft Samling As discussed in preliminary reports for previous Castle shots, the probability of collecting satisfactory cloud samples by means of manned aircraft is, to a very large extent, dependent upon how well the director and sampling aircraft can maintain visual contact with the bomb cloud. It is, perhaps, fortunate that weather difficulties forseen as early 4s eS (EY dia not actually arize until the last shot of the Castle series, Late in the afternoon on N-1 day an acceptable wind shear situation between 30,000 and 45,000 feet and acceptable cloud cover were predicted for shot day. Although an 8/8 cirrus layer was also predicted, no trouble was anticipated becausa this layer was predicted to lie between 39,000 and h1,000 feat, and it was probable that the director and sampling aircraft could climb above the cirrus cover and maintain visual contact with at least the upper portion of the cloud if not with the portions at the actual sampling altitudes. With such a visual reference, sampling can be carried out in a satisfactory manner. The weather conditions, however, worsened considerably during ths night and at shot time were characterized by an 8/8 cumulus cover frau 1,000 to approxinately 15,000 feet (absolute), an alto-stratus layer of unknown extent above the cumlus, and, still hizher, a total cirrus _ ©Over extending from approximately 37,000 feet (absolute) to what later Was established to be 52,000 feet (absolute). From its zero tine altituce of 10,000 feet (absolute), the director aircraft had no view of the baub 2 CoPface ~ LAWL RG rt a ™ :