Description of the YOKE Day Cloud
Then the candansation cloud vanished, the flaming gases whioh composed the
fireball were seen.
At about H-hour plus 16 sinutes, « swolling cumlus cloud with « top at
The flames arcund the base of the fireball seemed to spread oub
9,000 or 10,000 feet had formed near the sero island.
This cloud moved with the
over the inland and appeared to linger masentarily before starting upward, The quan-
easterly winds and was lost among other clouds at the end of fifteen minutes, Also,
tity of constituents in the fireball appeared considarably greater than on the TuY
at 16 minutes after H-hour, the highest portion of the atonio cloud waa in the fom
Day test,
There was an extremely rapid increase in volume and lateral spreading of
the top jn this early stage,
dianeter of cne alle,
of an anvil top, elailar to that found on a cumulonimbus,
In about 10 seconds the ball of cloud bed grow toe
This envil is thought to
have been caused by a spreading out of the top of the cloul as it flattened iteelf
After this initial rapid expansion, the diameter increased
against the stratospheric inversion,
The top of the clow seems te have reached the
nore slowly, At the end of ne minute, it is estimated that the mushroom top was
bane of the stratosphere in about 12 mimitea, but the anvil took about four minutes
about two miles in diameter. The brilliant yellows and oranges changed to red as the
to form, The spreading out of the top of the atomin cloud has been taken to be an
incandescent
gases cooled in about 20 seconds,
From about H-hour plus two minutes
indication of when the olood arrived at mximm altitude,
to H-hour plus five minntes, the cloud was rising as a large spherical mass on a
The highest part af the
atomic cloud remained in this anvil shape until about the trenty-fifth mimte past
broad stalk. At firet, it began to take the characteristic mushroom shape tut for
@
H-hour,
some reason, perhaps ite size, the cloud was not able to mintain the ring shaped internal clrvulation seen in previous clouds.
a gigantic bubble of gas.
The primery portion rose more nearly as
At H-hour plus one hour, the highest portion, or former "anvil," seemed to
Instead of the cloud material ceacading down the aide of
the mushroom and being drawn back into the bottom as on XRAY Day, the YOKE Day cloud
left a relatively thick trail of dust and sacke in its wake.
By the tine it reached
contain the only moisture in the entire clout.
It appeared to heave stretched out in-
to a rectangular patch of cirrecumius; whereaa the reminder of the cloud mintained
maximm altitude, there appeared to be « diminution in volume of the hot bubble be-
ite reddish-brown color and emoky, dusty appearance,
cause of the large quantity of mterial left behind, There also seemed to be less
draw out by the structure of the upper winds into a ribbon which bad extresities
moisture condensation associated with this cloud.
about 50
a
anoke
°
miles epart.
7
Fini
in width ¢
density,
Tut remained unbroken.
Generally speaking, it sig-sagged downward in a slanting line from east to west and
Loud»
Arter E
Insteed, it appeared to be more of
In one hour, the cloud had been
hour
Plus
tive minutes, the etalk of the mst
3
showed a
bend
to
the east as the strong westerly winds became effective, and at H-hour plus 12 minutes
reached completely across the northem sky. Its actual ahape 1a shown later in a
sketch (page 50) and in « photograph (page 68),
the cloud renched its muximm eltitude of 55,000 feet. Whan this altitude was reached,
the clowd consisted, from the surface upmrd, of a thick vertical mass estimted to be
one and qne-half miles in diameter which extended to 15,000 feet; a slanting colum,
tilted tovard the east,of irregular patches of reddish-brownsacks and dust; and the
In one hour the cloud bad moved amy until {t wes ese than 10 degrees above
upper dominant masa which was about five miles in diameter and three miles thick. 41)
the horizon; and after two hours it appeared at ouch a low angle, and ms so dispersed,
parts of the cloud were comected together, and there was never a clear break as
that its general form could not be determined,
oocurred on TRAY Day.