WMOD00299

• Title: Physical Structure of Northern Colorado River Basin Cloud Systems
• Date: 9/1/1985
• State: CO
• Weather Modification - Doc Type: Report

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4. Ice mul ti pli ca t 10 n. . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . 204
A. Rev lew . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .204
Crystal fragmentation..................................... .204
Ice splinter production during riming......................205
Droplet shattering upon freezing...........................206
particle fragmentation.....................................207
Surface observations.......................................207
Aircraft measurements................................... .'. .210
a. 5J anuary 82......... ". . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .210
b. 31 January 82.............................................213
splinter formation during riming...........................218
Physical constraints on the Hallett-Mossop (1974)

me chani am. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . , . . . . . . .219

a. Temperature............................................ .219
b. Presence of small and large droplets....................219
c. Presence of large ice particles.........................221
(2) Evidence for the Hallett-Mossop (HM) process...............221
D. Droplet shattering upon freezing...............................229
5. Accretion........................................................ .230
A. Review................................................ ......... .231
B. Accretion in upper cloud regions...............................233
(1) Cloud top region in warm clouds............................233
(2) Riming in upper regions of cold clouds.....................235
C. Frequency of accretion and effects on precipitation

distribution. . ... . ... .. . . .. .. -... ..... . .. .. . .......... .... .... .. .240

6. Aggr'egation...................................................... .~44

A. Review........................................................ .244

(1) Particle adhesion......................................... .244
(2) Physical parameters controlling aggregation................247
a. Temper a tur e. . . . . . . . . . . . . . . . . . . . . . . . . . . ... . .. . . . . . . . . . . . . .247
b. Crystal concentration.................................. .248
c. Crystal size and habit..................................248
(3) Collection efficiency and size spectra evolution...........249
B. Surface observations of ice particle aggregation...............249
(1) Surface temperature....................................... .249
(2) Precipitation rate........................................ .256
( 3) Crystal hab1 t. . . . . . . . . . . . . ... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .258
a. 13 December 81..........................................260
b. 14 December 81..........................................260
0.15 December 81..........................................264
d. 16 December 81.........,................................264
e. 21 De.oember 81..........,................................265
f. 29 December 81..........................................265
g. 30 Deoember 81..........................................266
h. 4 January 82..........,....................-............266
1. 5 January 82............................................ .267
j. 13 January 82.......................................... .267
k. 16 January 82............................................268
1.19 January 82............................................268
m. 21-22 January 82........................................268
n. 23 J an uary 82.......................................... .269
o. 27 January 82.......................................... .269
p. 31 January 82...................,.,..........~..........,......269'
C. Physical models of aggregation in cold cloud systems...........270

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(2)
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B. Ice
(1)
(2)
C. Ice
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