approxination to the actual case. Consideration of the extreme vertiCal velocities and violent turbulence existing within the cloud before stabilization makes it appear unlikely that any major fracticnation of particle size would occur within the cloud and stem at early times. dowever,any error introduced in the resultant axis of symmetry as a consequence of tnis assumption would be minor because of tae particular wind situation throushout Shot 1 fallout. (c) <A vertical line fron ground zero to the maximum elevation (da) Tne physical dimensions of tne cloud a: i stem can be of the clou” renresents the axis of synmetry of tne stem and cloud. Satisfactorily represented by assumins they define cylinders about the vertical axis of symmetry of the detonation. The above assuzptions defined a simplified model of the Shot 1 cloud from waich, with information obtained experimentally and the conplete wind data, the particle trajectories were calculated and their points of intersection with tne surface of the earth determined as well as were particle transit times. 6.2.3 Experimental Data Arplied to ‘Model Evaluation The following experiment2l data were used to complete tnis analysis: (a) rom the particle size aralysis of the Bikini Atoll and outer islend atoll fallout, (see Section 5.2) it was determined that the particulate were almost entirely irregular in shape. (bo) The average apparent density of these particles was de- (c) The size distribution of the fallout particulate ranged be- (d) The cloud dimensions botn vertical and horizontal were (e) Meteorological data of the variation vita height of both termined to be 2.36 g/cu cm as discussed in Section 5.4. tween 2009 ani 25in diameter, obtained by cloud photography. °/ the wind direction and speed, and the air tenperature were obtained fron tne Task Force Weather Central. 6.2.4 Determination of Particle Trajectories Fron consideration of the above essumptions and application of the measured particle data the terminal velocities of the fallout particles were calculated from aerodynamic faliing equatiors. (See Arpendix E.} The atmosphere was then divided into 5000-ft increments fron the surrace to 10C,000 f% and tne average wind speed and direction within these increments was determined. Witu knowledge of the rate of fall of the verious size particles and the wind vectors acting on these particles their trajectories were computed. Particles of 2000, 1500, 1009, 750, 500, 375, 250, 230, 150, 100, 75, 50, and 25 b in diameter were placed at 5000-ft increments in the cloud model. Each particle size at each starting elevation ».as then tiollowed through the atmosphere. Comprehensive use of the available wind data was made in computing the particle trajectories. Effects of both space und time variations on the winds were fully considered. The upper air data fron Eniwetok, Bikini, BL