ter blast to 72 hours after blast.
-
c,
about
General. contours of conductivity around the cloud showed it to be
and 600 to
300 to 400 miles long by 50 to 150 miles wide at 6 hours after the shot;
1,000 miles long by 100 to 200 miles wide at 30 hours after the shot,
The above
at the
information was obtained at 25,000 feet for the wind patterns which existed
times of DOG and EASY shots.
The existing wind patterns indicated that vertical
mixing occurred between the 20,000 - 35,000 foot altitudes.
The position and size
of the cloud could not be explained otherwise, since the cloud was several times
longer and farther away than predicted by 25,000 foot wind patterns alone, or by
fall-out, since the size of the particles measured was believed to be extremely
small.
d.
One rather unexpected result of the tests was an indication that a
surprisingly large portion of the radioactivity might have been carried on submicron
particles which were too small to be filtered out by the normal filter methods,
This
was first suspected when the activity collectcd on the filter papers failed to account for the actual ionization measured by a factor of better than 50 times.
So
far it: cannot be positively stated that these submicron particles are the major con
tributors to the activity of the cloud as compared to the 4 to 10 micron particles
collected by the filtcr papers, but it is very difficult to interpret the evidence
collected ta date in any other manner.
e.
The L-13s made flights at elevations ranging from 200 feet to 4,000 feet,
it was found that at an altitude of 200 feet the contamination contours on the shot
island and adjacent islands could be obtaincd rapidly from the air and that they
agreed very closely with the ground contours drawn by the radiological safety moni~
tors,
At higher altitudes, the entire atoll was examined from the air and the pat
tern of fall-out from the cloud was easily observeble,