WMOD00514

• Title: Preliminary Field Experiments of Snowmax on Cumulus Mediocris Clouds to Artificially Induce the Production of Ice Particles
• Weather Modification - Doc Type: Report

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Preliminary Field Experiments of Snomax™ on Cumulus Mediocris Clouds~
Artificially Induce the Production of Ice Particles.

James A. Jung in conjunction with
North Dakota Atmospheric Resource Board
P. O. Box 1833
Bismarck, NO 58502

Snomax Technologies
95 AlIens Creek Rd.
Rochester, NY 14618

ABSTRACT

SnomaxTH Snow Inducer, Pseudomonas syringae, has undergone preliminary
field studies to determine its ability to produce ice particles in
cumulus type clouds. Initial results show the production of ice
particles at concentrations of 100's/liter within 8 miputes after
seeding with SnomaxTH at temperatures near -5oC.

1. Introduction

The presence or absence of ice par-
ticles in continental cumulus clouds gen-
erally determines its efficiency to
produce rain on the ground. Typically,
except for the low concentrations of
biogenic ice nuclei (Schnell and Vali,
1976; Levin and Yankosky, 1988; Vali et
al., 1976) the atmosphere has a very
limited supply of active ice nuclei at
temperatures warmer than --150C. Even at
-200C the average number of effective ice
nuclei in the atmosphere is only about 1
liter-1 (Pruppacher and Klett, 1980).
Consequently this deficiency of effective
ice nuclei in continental c0Gvective
clouds, with cloud top temperatures
greater than about -12oC, produce little
or no rain (Pruppacher and Klett 1980).
It is known that large numbers of
living and dead microorganisms can be
found in rain, hail and ~;now (Gregory,
1967; Parker, 1968; Parker and Barso] m,
1970: Mandrioli et aI., 1973). Thc'se
microorganisms were assumed to be swept
out or collected by falling hydrometeors
until Schnell and Vali (1972, 1973) re-
ported that some of these microorganisms
were actually used as freezing nuclei.
Vali et aI. (1976) isolated a bac-
terial culture from decomposing leaves
which was the most effective in producing
freezing nuclei. Maki et al., (1974)
identified the bacteria as Pseudomonas
syringae, a bacteria normally found on
plant surfaces as an epiphyte. This ice
nucleation-active bacteria was found to be
active at temperatures between -20 and
-100C (Maki and Willoughby, 1978: Lindow
et aI.. 1978: Yankofsky et aI., 1981b:
Lindowet al.. 1982). Figure 1 compares
the bacterial freezing spectrum of Snomax
to AgI and dry ice. AgI activates between
-80 and -12cC, while Snomax will initiate
the the formation of ice at significantly
wa rmer ten:peratures (Ward and DeMo'tt
1989) .
Snomax (Pseudomonas syringae) aerosols
were found to be highly efficient and fast
acting, apparently nucleating ice by a

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F<.guJte. 1. CompaJU.6 on 06 .the. ice. CJuj.6.ta..t
yie.ld ve.M w.. .te.mpe.JLa.t.Wte. nOJt Snomax., MY
ice., and two 06 .the. mOJte. e.66icie.n.t AgI-
.type. ice. nucte.a..t<.ng ae.JtO.60t6 nlWm .6o.tu-
lion c.ombw..lion and PYIW.te.chrUc .60Junut-
a..t<.on. (6Jtom Wand and Ve.Mo.t..t., 1999)

condensation freezing mechanism and at
rates comparable to those of dry ice (Ward
and DeMott. 1988). Preliminary field
tests with Snomax showed visible
glaciation effects at temperatures as warm
as -50C (Ward and DeMott, 1988). These
results suggest a great potential for
Snomax as another ice nUCleating agent for
use in weather modification.
This paper reports some initial
results of seeding cumulus clouds with
Snomax for the purpose of ice production
for weather modification purposes.

2. PROCEDURE

2.1 Seeding Hypothesis

To study the effects of Snomax as a
cloud-ice initiating agent, cumulus type
clouds were used. These cumulus had cloud
top temperatures warmer than -6oC and had
little or no natural ,ceo These clouds
were seeded with a mixture of 80%
Pseudomonas syringae and 20% silica base
at the rate of 20 g min-1 during the
entire time the aircraft was in-cloud.
After seeding, subsequent penetrations
were made through the cloud near the same
height to measure the number of ice part-
icles. The liquid water content of the
cloud was also to be measured, but a

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