|
<br />
<br />main pul~:h:!_~t"rlved later ut un Hv~rug~ ri~~ rate
<br />of 1.2 m . '-, equalling Che averuge updratC
<br />o~scrvC:l!. Conccntrutiuns of le.: nuclc.t were close
<br />to t!le background values.
<br />
<br />i
<br />~+
<br />
<br />
<br />_ .....urw,,.....,
<br />..~ Cta"," TOI' ~~. ICI ,,".""."IKAIU.,O. "
<br />~tc:;~~~ ~~ ~.:.__...... ~ .
<br />~ t . . " -';-:-:;:~~A~'~
<br />. ... 10 f"f IO"{ 40r( ./' -;
<br />,~ " '... --- .- :..
<br />- ~ . ~', /" ; 0
<br />~ -/\. ..... '..., .-,' ....... .. ,;::
<br />J; n.OUD uu
<br />~ t \,JW--V--~....
<br />
<br />'t"too c:.
<br />
<br />.~
<br />
<br />
<br />I~
<br />
<br />Figure 3 AA alcicude-cime diagram of che base-
<br />seeded cloud 2 on 17 June 1976 showing
<br />cloud boundaries. aIrcraft alttt:ud~s Ullll ice
<br />concentrations.
<br />
<br />The second cloud on 29 July had a a~edl~g
<br />
<br />pulse of lee cryscalf and nuclei rising aC che aver-
<br />age raCe of 2.3 m s ,again nearly equalling chac
<br />observed ac hase. In boCh cases che pulse of ice
<br />cryscalti was at the sampling level for a time some-
<br />\lh~' t longer 'than the 9~edin~ dura cion. shoW'lng a
<br />vert;tcu.l str~tching of the Initinl plume. A crude
<br />estimate of this v~rtical 9tretching rate ill both
<br />caSeS showed ic Co be about half of che updrafc
<br />VUL"ii.tnce observeu at base. The 17 June experiment~
<br />dlJ (1(.'(. lend thcnlselves to any diffu::3ioll rate
<br />es t.imn Ces.
<br />
<br />A unique day of che summer was 17 June,
<br />when a small percencage (under 10%) of natural
<br />c.lo\.tds glaciated and produced show~r5 even though
<br />cloud tops were relatively warm (>-7 C). The
<br />natL:t'al cloud which visually appeared rnogC g.lac-
<br />l.dccd in the vicinity of the seeded cloud was
<br />tWIn!).l ed anc found. to h~ye pass-averaged crystal
<br />concentrations of 11).t '. :t is possible that.
<br />t:!Ven t~\uug!1 the cloud was lCc:-free initially, cry-
<br />~t8~S not resulting from seeding were pr~sellt in
<br />c.Lot!(t 2 on 17 June. Adjust.Lng for an ~~sumed nut-
<br />urit~ .'.ce c.rytital concentration of 15 .9.. ...... would bring
<br />the c~1culacec.l effectivBne::iS value closer to the
<br />.!..alJoratory curve in Figure I..
<br />
<br />~. CONCtuSIONS
<br />
<br />Both the pyrotechnic and acetone generator
<br />experiments showed AgI effectiveness values in good
<br />uf~reemcnt wIth laboratory values. \.Jel.l. above back-
<br />\rt.ol\I.\\H.1 ice \\\.\cl~u$ conce.nt.n\.tlon~ 'W~rt: a8:;;ocint~d
<br />~lt!l high iCE;: crystal concentrations 1n several
<br />cases. .lendIng support to t:he llypotbeg19 chat the
<br />cryscnls rcsu':ted from seedIng. Cry~tal ~rr~8ding
<br />rates were founc to be similar to updraft variances
<br />in t~e few cases that could be examlned. Base seed-
<br />ings often produced no detect~d re~ults because of
<br />insufficient updrafts for th~ times available dur.lng
<br />t~t;: experiments.
<br />
<br />7. REFERENCES
<br />
<br />Allee, P., n. PacCon and E. BarreCC, 1972: The
<br />.lynamic calibration of an airborne ice nuclei
<br />seneracor. J. Rech. ACmos. pp 29-42.
<br />
<br />::~
<br />
<br />'l.
<br />;. 10"
<br />~ r
<br />
<br />E 10"
<br />..
<br />..
<br />...
<br />"'
<br />'"
<br />~ .oIl
<br />..
<br />u
<br />...
<br />10-
<br />b
<br />10'
<br />
<br />:::r
<br />
<br />r(
<br />ti
<br />T
<br />"1
<br />
<br />1010
<br />o
<br />
<br />I
<br />-10
<br />T~"P'fRAru..!
<br />
<br />'J
<br />-20
<br />
<br />t f I t
<br />-"
<br />"C
<br />
<br />-.
<br />
<br />" .,F.i,gure, 4 The,effecciveness of 2% AgI-NH1,1 fro~ an
<br />Aero Systems, ~nc.. genf::'r-ut:o'L""'The '::..'8.h-
<br />oratory curve wa~ determined for :-1!!!U!.
<br />
<br />Dye,
<br />
<br />J.. G. Langer. V. Toutenhoofd, T. Cannon .!md
<br />C. Knight. 1976: ~$e of a sailplane to mt:asure
<br />microphysical effec~s of silver iodide seeding
<br />in cumulm; clouds. l.:......!\..2E~~., li,
<br />pp 264-274. --
<br />
<br />Garvey, D., 1975: Testing of cloud seeding materials
<br />at the cloud simulation and aerosol laboratory.
<br />1971-1973. J. AopL Meteor.. liI, pp 883-890.
<br />
<br />, L. Lilie, T. Grove and L. Grant, 1976:
<br />-----:Datermination of the rutes of ice crystal form-
<br />ation in two large cloud chambers. Preprints
<br />of International ConE. on Cloud PhY~ILc~,
<br />Boulder, CO pp 121-125.
<br />
<br />Magono. C., and C. Lee, 1966: ~eteorological class-
<br />1t1cation or nalural snow crystals. ~~~
<br />Sci., Hokkaido T}nl.v., Sere VII, 11 PP 321.-,362.
<br />
<br />McPartland. J.. 1\. Super and E. Holroyd, III, 1.977:
<br />Na.tural ice crystal conc~nt:.ration~ tn northern
<br />High Plains summer clouds. Prepr.lncs~ Conf.
<br />on Inadv~rt:.ent ant:! Planned t.!eather ~':odi.f !.catton.
<br />Champaign-Urbana, IL.
<br />
<br />Super, A., E. Holroyd, III. and B. Silverman. 1977:
<br />The praccicabi2.icy of dry lee for on-cop
<br />~eedlng of convective clouds. Preprl~~~
<br />Cunf. on Inadvertent and P1.anned' ~'(:ather :'~I)d-
<br />.If:.lcution. Champ.J.ign-lJrllann, Y.Lo
<br />
|