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4 WAY 1953
24 Apzil 1%3
iCTEMORAMDUM FOR RECORD
‘MBUBIECT,
2(Confidential) -Meight ef IVY (Restricted) Mike Cloud
ie
‘At the time ef the IVY Mike Operetion two airereft designated
WPSaltahaker” flew sace-track eeurses, ens de
approximately 70 nautical miles, the ether due east ef ground sero st
~appreximately GO smutical miles. The planned mission of these flights
was te secure a photograph of the IVY Mike eleud each minute fer ene hour
. “following the explosion. This mission was requested by Headquarters USAF
‘APOAT-] for after-the-fact cloud height saleulations
have
. “at yet been received, and may not be ef much value fer the intended putpose
wpeceuse of poorly defined er ebsent herizons.
2,
-Mmacheduled bubble sextant reedings sere made by Dr. WEEE
in the airereft to the south and Celene] Gp ef Headquarters USAF, APOAT-)
fin the aircraft to the east. <Airereft leren positions were provided by the
mavigator ef the aircraft who alee checked some of the angle ebservations.
siaheight and heights of various outstanding features ef the loud.
The obser-
|
iLaqations ef angle, distance to ground zero, and aircraft altitude sre believed |».
‘to be such that the calculated heights are ast in error ons may
agrate believe thet aanee enze Consideretion cf seme points wou
to believe thet no large errers were introduced by “edge” sighting and
obtaining erroneously high angles. Firet ef all, there can
=9f this kind ef error in sighting en the rether eharp-pointed plume which
-“myleléed en altitude of 135,500 feet.
The difference between this altitude
top of the eleud at around 120,000 feet was in the serrect proportion
athe the thickness of the sloud (120,000 ~ 67,000 © 43,000 feet)
eat the tine.niu, a ei
as judged
on the far right edge ef the cloud
aebe at 11.75 minutes in Table I) gave 104,000 feet and this san hardly be
‘fn error by 40,000 feet due te erroneous sighting arising fram edge and
thickness effects, as it would be if the cleud did not rise above the trepo-
pause.
Thirdly, the main shear layer meesured at 15.2 minutes in Table 1
_ gave an altitude corresponding exactly to that of the prognesticated principtd
@hear altitude for the event and we again judged te be at the sorrect pro-
portional altitude for a top at around 120,000 feet. Feurthly, the altitudes
of 110,000 and 112,000 feet at 2.66 and 3.42 minutes ere not explainable on
-false base line because of laterel movement of the cloud; air movements sre
not that rapid cempared with @ plane to ground zero base line of 66 aautics!
ailes.
Inclosure 1!
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