Ft. 100,000 PF TT ! |O r Km. T_T TTL 30 AIRCRAFT OBSERVATION O NRL SURFACE STATION 4 80,000F- = | 0.1 1 0.2 ot | ll 60,000 OO ar ; 0.3 oO Sa 0.45 2 Oo 03 40,0000 8. rl o* eee 988 78 2 55 0 4 _TROPOPAUSE ee PF O38 Leer Lo 20 |ko4 0.3 0.3 oo O. “IS ots +203 4 ~~ ~ L = 00.3 - 25 _ 0.5 16 MEAN 03 o oF Doe - 10 OOF 20,000 4 a 0.8 66 ob 80.3 -- 0 7 90° O ° bod 60° 4 0 0.5 -5 oO O 1 4g lo 30° i 08 08 8 eee OO; O° NORTH 30° 8? 60° Lilo 90° SOUTH Pb 210 d/m/|lO0O0 scf Fig. 4 -- Lead-210 distribution 31