| | T 80 DIS/MIN/1000 STANDARD CU FT C33? 60 | — gro 40 X ‘ N\ 20 / i -— SA i i i| 50k 60k | 7Ok ALTITUDE, FT ~ — | g0k 90k 100k DIS/MIN/4000 STANDARD CU FT Fig, 7a—Variation of Sr’ and Cs" activity with altitude. 40 - 65k 30 Lee - 20 -- BOk 40 F- 90K | 0 50°N boo 40° 30° 20° 4goe or 40° 50k 207) LATITUDE Fig. 7>— Variation of sr? activity with latitude, 37 30°S