the natives gathered together to discuss tho strange phenomena; the tize required for the evacuation was consequently short. - (5) Cloud tracking: The term "Cloud Tracking’, 2s used in the CaSTLE Radsafe Plan, is probably oore likely than not, 2a misnomer. The opera- tions could be more precisely considered as ‘aerial Surveys", being surveys of sensitive areas to detect the developmont of potentially hazardous con<citions. carly in the planning stageyof C.STLE it was realizel thst a strietlL cloud tracking operation at the Pacifie Proving Ground would be uneconomical if not practically impossiole, Considering the availability of aircraft to engage in such work, and the nature of the answers whieh were vital from a safety standpoint, it was epparent that certain areas in thu vicinity of the testing grounds were sensitive, whereas others were either not critical, or of interest only academically, It was also apparent that a cloud tracking effort of the type normally mounted for shots at the Nevada Proving Ground had little chance of success due to the extreme differential in cloud heights for the two proving grounds, also, due to the fact that normally there are at least two major angular wind shear lewels at the Pacifie Proving Ground, » considerable number of aircraft wuld be required to follow cach of the thre or more cloud segmenta formed, whereas tnc normal situction in Nevaca is one low major shear lewel and therefor only thc one mijor upper clu scgment to follow, To be perfectly precise, considerablu angular shear is prescnt in most Nevada clouds; however, relatively speaking, the sector of cloud travel in Newada 4s wery narrow compared to the wide sector of travel csusei by complete reversals of wind directions in the Pacific, The normal concitisons at the PPG latitude is east-northeast trade wind flow up to ten to twenty thousand feet, easterly flow above thc tropopause (i.¢., above appreximcteiy fifty-Cive thousand fcct) and variable winds between. 37 Since favorable shot