Northwest, no shots, , 7 West, 1/2 shot. (It is noted here, however, that the March 7, 1955, cloud went west and later curved around to Northwest short of Tonopah.) — Southwest, 2 shots, South, 4 shots. . , .. Tonopah is almost due northwest of Nevada Test Site. Analysis of the record shows that only the outer fringes of one cloud went near Tonopah in six years of testing, while the main cloud or substantial portions of it went over Indian Springs, Las Vegas, Nellis AF Base, and Henderson on 12 occasions, It is obvious from the above that the Nevada Test Organization does not "wait until the cloud will go north or northwest before firing." ‘Factors considered: There are some shots in which the detonation will be sufficiently above.the earth's surface so the direction and speed of winds is not too important. Possibly the determining factor in such instances would be.the possibility of rain or snow from an altitude above that of the atomic air mass at some point within 200 or 300 miles downwind. Tle key factor-on such shots is that they do not result in early deposition of fallout. - Surface or shallow underground shots would create heavy, very early fallout. For this reason, there are serious restrictions on the yield which would be permitted under such positioning, and stringent criteria as to wind directions and strength are established. Such shots would not be fired unless the wind was out of almost due west, west-northwest, southeast, or south, so that all early fallout would be on the Test Site and on nearby, uncccupied portions of the Las Vegas Bombing and Gunnery Range. A number of shots at NTS offer the potential of fairly heavy early fallout. These are almost exclusively tower shots in which the fireball will touch the ground (none of which are scheduled for the Summer 1957 series) or those which will create fallout out of the tower or materials and instrumentation associated with the tower cab. For these shots, much more stringent criteria apply than for high air bursts (such as with balloons or air drops), although they are less stringent than apply to surface or shallow underground shots. It has frequently been reported that on shots such as those discussed immediately above the only hazardous fallout has been, and would be, within no more than perhaps up to 20 miles from zero point, which in every case would be within the Test Site or adjacent areas of the Bombing Range. The levels of radiation in the hottest hot spot within the 20 miles has in one instance equalled an infinity exposure rate of 30 roentgens, or an estimated lifetime dose of 18 roentgens. There may, however, be less but still undesirable fallout at greater distances. This might range from 4 roentgens to perhaps 10 roentgens, It is very seldom that forecasts indicate fall<¢, -_. out levels anywhere in inhabited places near the Test Site that ee) we ~ 52 -