Title: 9 Things That Every Farmer in Georgia Should Know About Cloud Seeding
Full Citation
Permanent Link: http://ufdc.ufl.edu/WL00002543/00001
 Material Information
Title: 9 Things That Every Farmer in Georgia Should Know About Cloud Seeding
Physical Description: Book
Language: English
Publisher: NAWC
Spatial Coverage: North America -- United States of America -- Florida
Abstract: 9 Things That Every Farmer in Georgia Should Know About Cloud Seeding
General Note: Box 10, Folder 22 ( SF Water Modification - 1981-83 ), Item 13
Funding: Digitized by the Legal Technology Institute in the Levin College of Law at the University of Florida.
 Record Information
Bibliographic ID: WL00002543
Volume ID: VID00001
Source Institution: Levin College of Law, University of Florida
Holding Location: Levin College of Law, University of Florida
Rights Management: All rights reserved by the source institution and holding location.

Full Text

Modern cloud seeding techniques
recently have been introduced to
Georgia, with far reaching economic
implications for every person in the
state's farming community. In the near
future farmers will be called upon to
make decisions regarding the further
use of cloud seeding technology as a
water management tool. This brochure
is North American Weather Consul-
tants' attempt to answer some common
questions that Georgia farmers may
have about this subject.

CC. -(


I, H k I L 1 I ,, i

1e What is cloud seeding and
what has it been used for?

Cloud seeding is the intentional
treatment of individual clouds or storm
systems for the purpose of achieving a
beneficial effect. The basic principles
of cloud seeding were established in
1946. Since that time numerous re-
search programs and operational proj-
ects have proved its applicability for
many purposes, including snow pack
augmentation, hail suppression, fog
dispersion, lightning suppression, as
well as rainfall enhancement.

2 What are the principles of
cloud seeding for rainfall

Clouds are composed of miniscule
droplets of water. Although water
normally freezes at 320F, cloud drop-
lets are so small and relatively free of
impurities, they can remain in the
liquid state at much colder tempera-
tures. At least some of these droplets
must freeze in order to create rain.
Unfortunately, some clouds may not
rise to the altitudes of the required
colder temperatures. The ice forming
process may then be enhanced by
introducing additional impurities, or
seeding agents, to the cloud. Particles
of silver iodide are typically used as
these seeding agents.

3. Are all clouds seedable?

Cloud seeding is simply the stimu-
lation of natural rain producing pro-
cesses, similar to applying fertilizer to
a field to stimulate the natural crop
growing process. Most summertime
precipitation comes from cumulus
clouds, the fluffy white clouds with the
cauliflower appearance. Large cumulus
clouds do not require seeding because
they contain enough natural impurities
to make them effective rainfall pro-
ducers on their own. Conversely, very
small clouds are not seedable because
they are typically incapable of produc-
ing measurable rainfall under any con-
ditions. But this still leaves a great
number of moderate size clouds which
can be effectively seeded for rainfall
enhancement. Obviously, the amount
of seeding material delivered to any
given cloud must be tailored to the size
of the cloud. This can only be accom-
plished by direct delivery of the seed-
ing material by aircraft.

4. What happens once a
cloud is seeded?

Two actions may result from seed-
ing. 1) Ice crystals form and grow big
enough to fall as rain. 2) When seeding
material is delivered in large quantities,
and in just the right place within the
cloud, an effect known as dynamic
seeding will occur. Large quantities of
water are converted to ice and, in the
process of freezing, heat is released
into the cloud causing it to grow larger
and higher. This larger and higher
cloud then produces more rain. The
diagrams below illustrate the process
of dynamic seeding.


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U I A I I .J 1 I j it1


326F .

Time: 5 min. 10 min. 15 min. 25 min. 35 min.
Cumulus starts Few large More large (1) Ice crystals grow larger at Light rain con-
building. drops form. drops and few expense of cloud droplets, tinues as cloud
Cloud grows, ice crystals fall through cloud, and dissipates.
form. Cloud melt into large drops.
reaches (2) Large drops coalesce with
maximum other droplets and grow
height, into raindrops which fall
to ground.


10.F -, __

Time: 5 min. 10 min. 15 min. 25 min. 35 min.
-Ice Concentrated charge Great amount of heat is re- Much more water is
S d d s of silver iodide (Agl) leased when supercooled processed by larger
**_f -Liquid droplets delivered into updraft drops freeze, causing sub- cloud, resulting in
-' -Agl nuclei of cloud. stantial cloud growth. more precipitation on
the ground.


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5o What evidence is there
that dynamic seeding works?

In 1968, the U.S. National Oceanic
and Atmospheric Administration initi-
ated a series of research experiments
to develop the techniques of dynamic
seeding. Called the Florida Area Cumu-
lus Experiment (FACE), this program
has demonstrated: 1) that rainfall from
individual cumulus clouds can be in-
creased up to 300 percent, and 2) that
rainfall over a large area can be in-
creased by about 25 to 50 percent.
FACE is a continuing research program
budgeted at approximately one million
dollars per year. It not only proved con-
clusively that dynamic seeding works,
but it also developed the technology
available for practical applications in
areas with climates similar to Florida.

6 What evidence is there
that the same techniques will
work in Georgia?

Summertime cumulus clouds
occurring in Georgia are very similar to
those studied in the Florida FACE
program. Thus, when a drought struck
Georgia in the summer of 1977, farmers
in three areas of southern Georgia
(Dawson, Statesboro, and Waynesboro)
organized operational seeding pro-
grams using the technology of dynamic
seeding. The programs were conducted
by North American Weather Consul-
tants over a period of 4 to 6 weeks,
with the results indicated on the chart

below. Although this data base is too
small for a conclusive evaluation, the
indications are that rainfall was in-
creased about 29 percent, which com-
pares favorably with what would be
expected based on the FACE research.
This 29 percent increase represents
approximately two and one-half inches
of additional rainfall in a six week

i 13

cc 12

to L)


6 7 8 9 10 11 2? (3

Comparison of precipitation amounts
observed in the Georgia Cloud Seeding
Target Area to predicted amounts
based on surrounding area rainfall.


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I L li L1A A .A l i L1 I J. 1

7* Are there any negative
effects.from seeding clouds?

No. The possibility of negative
environmental impacts toxicity of
seeding material, or creation of severe
weather conditions such as hail storms
and floods have been considered
and studied extensively in FACE as
well as other seeding research pro-
grams. All the evidence shows that
there are no negative effects from seed-
ing clouds, provided the programs are
conducted properly by knowledgeable
scientific organizations.

*e Who are North American
Weather Consultants?

Since 1950, North American
Weather Consultants has been a leader
in research and practical application of
the new science of weather modifica-
tion. The firm has conducted almost
200 project seasons of cloud seeding,
to increase water supplies throughout
the United States as well as several
foreign countries. Boasting the largest
permanent staff of commercial weather
modification experts in the world,
North American Weather Consultants
was selected to operate the 1977
Georgia Cloud Seeding programs on
the basis of its reputation and
experience with dynamic cloud seeding.

9F What are the future
possibilities of dynamic
seeding in Georgia?

While drought relief is a demon-
strated application of dynamic seeding
in Georgia, the use of this technology
in normal water years can yield even
more significant benefits to the farm
community. Knowledgeable farmers
have long known that additional rainfall
can produce greater crop yields in most
years. Dynamic seeding should thus be
an integral part of a Total Water Re-
sources Management program for farm-
ing practices. The benefits derived from
such a program would certainly justify
the relatively small costs involved. The
1977 programs in Georgia were funded
voluntarily by the local agricultural
community in each area. Plans are
being developed now to expand the
program to cover a large portion of
southern Georgia, so that both cost
savings and a more equitable basis for
funding can be achieved.


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