Chapter 4
DISCUSSION
Aol
ABSOHPTIVE EFFECTS
A tentative explanation of the protracted absorptia observed at Site Elmer has been evolved, It is based on the fact that the
atomic clow! containing radioactive particles rises quickly to about
120,000 ft. At altitudes of about 60,000 to 120,000 ft, there are,
at the latitude of Bikini, continuous easterly winds having velocities
generally increasing with height to something of the order of 60 to
90 miles per hour, Thess winds could carry the aforementioned particles
to the region above Elmer by about 2 hours after the detonation.
These particles are capable of supplying sufficient ionization to the
air, despite the rapid recombination rate at these low heights, to
cause the onset of the renewed absorption shown in Table 31.
The
time given in the table for renewal of absorption after Shot 5 seems
scmewhat early (+1 hr 36 min), so either a different cause of
absorption was in operation at that time or higher velocity winds ex-
isted. The latter possibility seems quite likely, as easterly winds
of over 80 miles per hr were reported at altitudes of about 85,000 ft
above near-by weather stations earlier that day. At higher altitudes,
the westward velocity may well have been 50 percent greater, whicao would
account for an early arrival of radioactive particles over Elmer.
The possibility that high velocity winds may have brought the particles
there early does not preclude a long duration of absorpt‘on (as observed), because continuation of absorption may have been due to lower |
velocity winds, at lesser altitudes of the same region (60,000 to
120,000 ft), carrying ioni:ing particles overhead at later times.
Ae2
F2eLAYER PHENOMENA
From the detailed description, given in Chapter 3, of the
phenomena associated with the individual shots, it is apparent that
the results obtained from Operation CASTIE are not as useful for
studying the F2-layer phenomena as those obtained from IVY Mike.
Dve to the absorption discussed in Section 4.1, and probably also dus
to a G condition, the actual period during which the F2 layer was
apparently rising was not observe?, but only that phase was seen dure
dng which the layer was returning to its normal condition (and this at
one station only). Furthermore, the extreme height that was found
66
SECRET