aT Ri
le SUSGRTW-
PRR.
aan
3
: ‘Thiel stomte devige UNION of Operatdiom CASTLE wae detonated ad 1210 howe
Zebra’ 26 Apri 19540 The UNIOM cloud reached an altitude on the order
95,000 feet. The iir Rad Safe operational im connection with this detonation.
were successfully conducted anc resulted in auch timely infermaticn os the.
Peat.
jJacen&
conditions net only or the show atoll of BIKINE tu® alsa the ade -
sfeage. Cloud tracking aircraft obtained data which indicated ths® the .
léweet section of the UNION clout stem, up ta perhaps fifteer thousand foet,s
was moving to the weet-nortines® at. approximately fifteens motsa This move—
ment, plus the moderate intensities encountered (a maximum of 60 Mr/tir),
established the fact that this portiom of the cloud did no® constitute a
hasard to ENT ETOK ATOLL 186 miles ta tie west of BIKING. Ancther aircraft.
made contac® wits fallout from the middle level (twenty to sixty thousand fees
of the clouds is had boers forecast by the presho® studies, this level was-)
proved ta be maving ta the east-northeas® ats fifteen krictae. Because of tha.
extreme height of the cloud, ne contact: wae nade with fallout from the top
level of the clouwf. From the musteorclogical data cue would predict a move
Om the basis of the foregoing it was.
ment to the north and te the west.
apparent thet there wae no hazard: to the populated atolls withis or without
the Pactf{ie Proving Ground. This premise was verified when one of the cloud
tracker sircraft was diverted for the purpose of making « minimm altitude
radiological survey of all land masses which conceivably could have bees
affected by fallout of UNION debris. This hurrted survey showd essentially
ne areas to have received fallout; a fact which wae confirmed when a more
- leisurely and refined, survey was possible. There was na evidence of signifi~—
cant fallow’ outside the Pacific Proving Ground.
2. GENER/Zs
ae
Squressof Information:
‘Cloud tracking information for UNION was available from five sources.
The contribution of eack of these sources, which are listod below, will be
discussed in subsequent paragraphs.
Sampling Aircraft Roports
Sweet~Sour Reports
Special, Cloud Tracking Flights
Weather Reconnaissance Flights
FO.T-1 Flights
b.
Overall Cloud Movement (within the PPG):
The BIXINE winds observed shortly sftor shot time are plotted in
the hadographa. From the hodographs is can be scen that the UNION cloud,
whose maximum height was of the order of 111,000 feet at 45 minutes, was
subjected to ‘area wind shears. The lowest level of the cloud (surface to
fiftsen thousand feet) was influenced by the winds from the east which aver=
Inel 6
N~32
°