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SUBJ: -The Relationship Between Rnergy and Rate of Cloud Rise
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FROM: POR
«40s DATE 12 Dee 52
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As you suggested last week, I have gone over all available dats on the
-s@pates of rise of cloucs from U.S. atomic tests and have plotted values for the
wates of rise againstzpmezgy in EKT, es show in the sccompanying graph, togethe=
«ith the empirical equition of rélationship.
2.
The sate of rise changes with time, increasing to a mniximam during the
‘first minute and decreasing thereafter to essentially zero after about 10 minutes.
‘The data available to us are not good enough to show the maximum rate dus to poor
wejming and infxequent measuxenents, but may be used to obtain the average rete off
*wise over a period of mimites. The everage over the ini
‘this graph. in all cases except IVY like the clouds were still rising rapidly
and were still in the troposphere after the third ainute. The Mike cloud was
“~*eected in a special manner as indicated below
jh
Xt is reasonable to believe there to be scme dependency of rise rate on
“sthe lapse of ambient air temperature with altitude.
The effect of inversions and
~etable layers will, however, be a minimm in the earliest seconds of rise, increasing
<4n importance es the temperature difference decreases between cloud and
s@tmosphere. When the clo reaches ambient air temperature, further vertical motion
is damped out. It is therefore preferable to measure the rate of rise st the earliest
possible time, and the maximm rate of rise should be more indicative of-enargy than
=the mean S-minute rate used hore.
;
"Since the mean lapse sate of temperature ie markedly different in the
~etratosphere than in the troposphere, it 1s preferable to maxe all measurements in
~the troposphere until adequate corrections can be made for this.
Je
Rate of rise data are available from the following sources:
a.
a
-M@pexationSASTOE, Me. Paul Humphreys, USHB, documented the
. ‘Wise and dispersion of the SANDSTONE elouds in an AFSWP publication, "Classified , ‘Selentific Meteorological Information, Operation SANDGTONE.” His data vere obtained
\by thaeodolite and eze reasonably accurate over at least the first fer mintes of rise.
be
GREENHOUSE,
‘The rise of the GREENHOUSE clouds were eb-
‘tained from an unpublished report on “Cloud Physics", Proje 4.6, by Dr. W.Wf.Kellogg,
Rand Compe Motion picture photography were analyzec fcr cloud vise and cloud
dimensions, and the ra tes of rise over the first 4 or 5 minutes are probsbly good,
although weather clouds obscured parts of the atomic clouds. The maximm altitudes
of the Dog and George clouds are stil) im doubt since the tope of these ¢louds were
not visible from the camere positions,
Co
BUSTERWJANGLE, Two sources of cloud rise data ere
available for these operations, one being that taken by myself (with your help in a
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