upon the altitude involved and the delineation of a2 sectcr by tha liniting resultant wind voctors. .. fifteen degree sector was added to each side of the falleout area to provide a factrr of safety for diffusion, instability of the pattern and wind variation with time and distance from dedour end Gi. Since the wind vector diagram (or hodograph) was normalized to §,006reet, per hour, the value of any resultent wind in hours was detormincd by the altitude for which 10 was plotted divided by 5,000. Since equi-tize lines teken directly from tho hedograph represented a fall-rate of 5,000 feet rer hour (approximately the rate of fall of a 100 micron rerticle), this distance was increased by doubling, tripling, etc., %t5 consider particle sizes of lesa than 100,microns, For the Miret sh«t, rarticles down to 70 microns were assumed to be. significant. Tris amcunted to considering populated areas at. distances @ total rosultant «dnd vector at each altitude, Subsequent to the first shot,eichtoen to twonty- four hour fall-out periods and 2istences reproseted by tripling and quad= ruplinz tte total resultant wind vector were considered. Considerations of land surface and water surface shot sheracteriatice asterially mocified these assumptions subsequent to the second shot, the m-dificaticns tonding toward a reducticn to distances revrasented by not more than twice tha total resultant tind weetor for simificant health hasard fall-out, =nd at least twenty-four hours for fall-out of simificance to test an¢ induatrial standaris, It should also be mntionod that the hocdograph, or wind voctor diagrem, Seing the besie framework of both the ak aprr-ximaticn method of fall-out forecasting andthe rectiniincar vector method, wis found extremaly usefulin the zraphic presentation of the progresaive «ind . observations cmd forecasts mice daily during the operation. Consoquently, “raw hodograrhs were centinucusiy used by Uadsafé as c measure 2f the "pulse™ of the daily tronda in the wind patterns and. in the grachic oresoncation of tho wind picture curing csmmand briefings. « complete scories of daily hedograrphs has been proparod cnd reproduced covworing the reriod February thr-uch May 1954 for documentation and future convaiiont study of interested personnel. (See also Tab I.) bd. The method of elliptical approximation of the fcll-cut pattem mentioned above is twred in USP DC Report No. C3-36417, November 1953, Radicactive Fall<cut from ctamic Bombs, as amended by USF “RIC lepcrt No. Cho16098, Mareh 195k (relative ts C.STLE 3u.VO Pall-cut and allied in-li- cations). Essentially the method starts «ith the "raw" fcrecast hodozranh. With thie es « basis, ellipses are dram with the portions of the hodosram between major shear levels as approximate major axes. Minor excs <re determined in acecrdance with the engular shear existing between mejor shea levels and.in secordance with the following empirical rulos: _ (1) If the wind shear is leas than 10 degrees for tho levels in question, the minor axis is 1/8 tc L/b-of the masor-axis. (2) If the wind shear is groater than 10 dogrees but lsss than 120 degrees, the minor axis of the majcr axa.