a ee” breAllen/vhk/62189--—. SUBJ: The Relationship Beticen Energy and Rate of Cloud Rise TO: Dre fie De Urry FRU: 7. We Allen (3 J DATE: 11 Dec 52st As you suggested last teek, I have gone over all available data on the 1. rates of rise of cloucs from U.S. atomic tests and have plotted values for the rates cf rise against energy in EKT, 2s shown in the accospanying graph, together vith the empirical equaiion of rolcticnsiiipe 2e The rate of rise changes with time, increzsing te a mixicam during the first minute and decreasing thereafter to essemially zero after about 19 minutes. The data available twvs cre nut good enough te shew the maxirsm rate due to poor timing and infsequen. mecsurcucuts, but ucy Ue used to obtain the average rate of¢ rise over a period of mimics. The everage over the initial 3 minutes is used on this graphe in eli cases exces. IVY Mine the cleucs were still rising rapidly and were still in the troposphere after the third rinutee treated in a special manner as indicated below. Tne Like cloud vas It is reascnadle to believe there to be some dependency of rise rate on the lapse of ambient air temperature sith altitude. The efiec. of (nversions and Stable leyers will, hovever, be e minimmsa in the earliest seconds of rise, increasin tin impertance 2S the temperature ditiertence decreascs between cloud and surreunding ctmcsphere, When the cloud reaches ambient air tenperature, further vertical motion 4s damped out. It is therefore preferable to sacasure the rate of rise at the earlie: pessivle time, and the maximum rate of rise should be more indicative of energy than the mean 3-minute rate used here. Since the mean lapse rate of temperature is markedly different in the stratosphere than in the troposphere, it is preferable to make all neasurements in the troposphere until adequate corrections can be made for thise . 3e Rate of rise data are available from the following sources: Be Qveration SANDSTONE. lr. Paul Humphreys, USIB, documeated the tise and dispersion of the SANDSTC:E clouds in an AFP publication, “Classified Sclentific Ueteorolegical Information, Cperation SANDGTON=." His data vere obtained by theodolite and are reasonably accurate over at least the first few minutcs of risc be GREEIZiIOUSE. The rise of tne GREEIHOUSE clouds were obtained from an unpublished repcrt on “Cloud Physics", Proj. 4.6, by Dr. W.t/.Kellogg, Raerd Cerpe iiotion picture phcicgraphy were analyzee fer cloud rise arc cleud dimensions, and the ra tes of rise over the first 4 cr 5 minuctcs are probaply good, although weather clouds obscured parts of the atomic clouds. The maximm altitudes of the Dog and George clouds are still in doubt since the tops of these clouds were not visible from the camera positions. Co BUSTER-JANGLE. Two sources of cloud rise data are available for these operations, one being that taken by myself (vith your help in a (Sf Copleas/DoE LANL, J-Div, Incl 1)” wee Ey ne) mS C ’