WMOD00311

• Title: Harold D. Orville Symposium - Forty Years of Modeling Clouds and Weather Modification
• Date: 4/26/2003
• Weather Modification - Doc Type: Report

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I)r, Ihuold n, On'illc, nistin~uislll'd Professor Emeritus
South Dakota Schoo] of Mines and Techno]ogy

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Dr. llamld Duvall Orville. Dlstinguishl'd Professor
Emeritus of Almospheric Sdenl'Cs at the South Dakola
Schoo] of Mines and Technology. was horn in Balti-
more 2.1 January 19.\2.lhc second of thrl"C sons ofeap-
lain lIoward T. and Lillian Orville. lIis Carl"l"r sl..'cnx.-d
headl-d loward the lega] profession when he graduah.'d
from the Universily of Virginia with a BA in Political
Science in 195~ lIowcwr, the U.S Army called him
and sent him to 1'1. f1uachuca. Aril.Ona. whl're he be-
C:lIne a Signal Corps 1I11'leorologist. which ultimalely
led him into his father's profession. ,\fter being dis-
charged as a First l.iculcnant. he el1lcrcd Florida Slate
University and complcll'd an \IS degrl"C in \tell'owl.
ogy. II.: thcn mowd with his growing family back to
ArilOna. whcre hI.' earned lhe PhD dcgrcc in meteorol-
ogy allhe Uniwrsity of ArilOna in 1965 under the tute-
lage (If Professor J;m'ICs E. McDonald. lIis younger
I1mthcr. Richard E. Orvillc. was a contcmporary gradu-
lItC sludl'nt in Meteorology at the University of Arizona.
suggesting the possibility that dedication to '\Imos-
phcric Sciences may have a genclic componelll.

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I. Research Can.-cr

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Aboullhc limc Harry l:ompklcd his gr;llluate stud-
it's. Dr. Richard A Sl:h]euscner was assembling Ihe
inilial slaff for the Instilute of Allllospheric Sciences at
the South Dakola School of MIllCs and Technology.
The Inslitute was gearing up 10 condut-I weather modi-
ficalion research ulld.:r what l-an... to he ~noy,'11 as Ihl.'
Bureau of Reclamation Skywalcr program - and Ilarry
had aClually given a spel'Ch about weather n!OdifiC;llion
during his f<nior year al Virglllia. Schleusenl'r some-
how {ll'rsuadl-d lIaITY and his family. now numhcring
four chi]drt'n. to make lhe trek in Fehruary ] 965 from
sllnny Tucson northward along the Front Range 10 the
Black Ihlls of South [lakota The Irip ilself. through
one of those all-too-common Front Range snowstorms.
would ha\'c IUrIll>d back many, bUlllarry and Ihe family
flxk' it oul and call... to slay.

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His Ph[l rl.'scarch at Arilona had COnl:l.'ml-d cloud
phologralllnll'lry, studying the cllmuliform dewlop-
menU; mer the C:lIalina Mountains near Tucson. This
]ed to a Iifdong in\'oh'en~nl in cloud physics. lie also
began his work on nUlnl'rical cloud modeling around
1965. in the era of punched card decks and the in\! 650
mainframe computer. J II.' later connl.'cted Ihl.' IWo in
numerous Iwo-dimensional simulalions of clouds lk-
\'doping o\er a Ilat plain wilh "MI, Orvillc" ;n Ihc
middle. Man)' will recall Ihc various plols and lill~-
IapSl;.' movies of Illese cloud dl'\'e]opn~nls, with grow-

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ing sophistication as lllodcling and compuling capahil-
ities improwd, lie ha.s always paid close allention 10
comparisons bctwl.....n thl.' modd .simu]<llions and l:orre-
spondlllg ohsenalinns - perhaps hcc<luSC his initial
research was ohservaliollally ba~-d

Harry and his stulk.'nls and collcagues gradually
inlroduced Illore realistic clements of cloud physics inlo
thc IllHnl.'rical models: amhil'nt winds. wind shear and
COIl\'Crgence. cloud shadows on the ground. and so on
They paid special aUenlion to simulating doud mit.ro-
physical processes. aI flrsl in so-called '.bu]~ moods"
where hydrollleh.'Of catcgories are deStTilll'\l only ill
terms of mass cont"Cnlralions wilh SImple analytical
particle-sil..e dislrihulioll funclions. Later modcls ill-
\'oh'ed many partide sitc calegories, with gains and
losses to each category represcnled hy Ihe appropriale
physical processcs. The ll11lllds ITlOVl-d from dOllds
containing only liquid partides (cloud droplets and
raindrops) 10 add cloud ice particles and snow and
e\'elllually graupel and h:li] Oht'n the focus was on
understanding and properly simulating hasic physical
prOl't'sses: the freczing of lilJuid water and thl.' re]ease
of ]all.'n1 heat. prccipilation loading. and the like. Some
of the early papcrs dcah wilh compuling prohlcOls aris-
ing from use of finile differcnce tcchniqul.'s. especially
011 Ihe early gClll.'ralions of compulcrs. Thc rdati\'c im-
pon,lflct' of Iho:-;c prohlems has fOrlunatcly dinllnishl-d
in laler years.