FIGURE 2
Pu-239/Sr-90 Ratio Just Above the Tropopause
SON
2 PEP PAY 2 AEC wee
7ogs
et
Ju
|
Jy
rea
TT
t-te
Au
S
O
N
D
J
F
Mr
Ap My
Ju
Jy
rere
60 lt *t
Au
S
{ft
OF
N
D
J
{of
F
Mr
Ap My
nia
sae
meSntees te
+
Vek Mi ate
ee ee
if
are temples
+
CONTOURS ARE IN PERCENT. ARROWS INDICATE THE DATE AND RANGE (SMALL ARROWS - KILOTONS; LARGE ARROWS MEGATONS) OF ATMOSPHERIC NUCLEAR WEAPONS TESTS IN EACH HEMISPHERE.