STATUS OF GLOBAL FALLOUT PREDICTIONS 108 | | | I i q Toy UT | TRAJECTORY, FT io] 9000 12,000 10° — z > 10 O < 10° 10° 377 _ JAN. 29, 1951 ALTITUDE, 9000 FT 95°W — —_ —_ — [tte | PEt tT tl 34N 36°N 38°N 40°N 42N 44°N LATITUDE TTT Tt) a01a Ts TRAJECTORY, FT lo° z 5 10" 15,000 FT B2W | | —_——___ —_ __ U << 10° —_—— — es ae Oe ee —_— GO | 14°N 16°N 18°N 20°N 22°N 24°N 26°N 28°N 30°N 32°N LATITUDE Fig. 7—Aircraftfilters obtained in cross-wind flights during Operation Ranger illustrating effect of directional wind shear. stratospheric fallout. Thus, during and for a month or two following a nuclear test series, the fallout associated with the series is classified as tropospheric fallout; afterwards, the fallout is classified as stratospheric fallout, It has been suggested that shortly after the cessation of a test series, if confusion arises as to the source, the origin of the radioactivity may be obtained from a series of successive ratios of a short-lived to a long-lived isotope, If the decrease with time in the ratio follows the decay of the short-lived isotope, the sourceis attributed to the stratosphere where scavenging is not present.