Sunday, July 16, 2000
Cloud seeding program succeeds;
another planned
By Bobby Horecka
Reporter-News Staff Writer
Regardless of the number of pipelines built
or reservoirs in place, nothing carries the power to resolve water
concerns like a few good rains.
But like so many other resources in West
Texas, rain is a limited commodity, not only in abundance but
in frequency. Some Big Country residents think harvesting showers
on a more regular basis is possible.
George Bomar, senior meteorologist with
the Texas Natural Resources Conservation Commission and one of
the area’s leading proponents of cloud seeding, agrees. However,
other meteorologists suggest that modifying the weather can have
damaging consequences.
More than 80 percent of the annual area
precipitation comes in the form of thunderstorms — flash
storms that can brew up in a matter of minutes, tear through the
countryside and be gone in less time than they took to form.
While cloud seeding won’t increase
the number of rainstorms, it can make the most of those that do
blow through, Bomar said.
By catching the right clouds at the right
times and applying the proper rain-inducing agents, seeding can
increase the rainfall over a given area by as much as 30 percent,
Bomar said, basing his estimate on more than 30 years of overseeing
weather modification programs across Texas.
Nine programs now exist, stretching from
the Panhandle to the Rio Grande, with the eldest not far from
Abilene in an area surrounding Big Spring. Dale Bates, coordinator
of the West Texas Weather Modification Association based in San
Angelo, said rainfall has increased by 30 percent during the 30
years of the program.
Like most projects, funding is the most
critical aspect of the rain enhancement program in Big Spring.
Local estimates set the costs at about $700,000, which would be
shared among the residents of an 18-county area.
The cost is nominal when compared to what
the added rain can mean, said Bates. He estimates a $700 return
on every dollar spent on cloud seeding.
Reports issued by the Texas Agricultural
Extension Service indicate that a single inch of rain can have
regional economic impacts of more than $283 million, particularly
when those rains saturate crops during their peak growing seasons.
Making a cloud rain more is simply knowing
how a rain cloud forms, Bomar said.
Wind updrafts draw moisture in the form
of microscopic water droplets, shooting the tiny drops high into
the atmosphere. In most cases, those tiny, super-cooled droplets
turn to ice, attracting other micro-drops until enough form around
the ice crystal to produce a single raindrop, which falls to the
ground when it weighs enough.
But late afternoon summer thunderstorms
often form so quickly with such fierce updrafts and major temperature
variances that the ice crystals never form, Bomar said. Though
the clouds are loaded with thousands of tiny moisture droplets,
the absence of ice crystals prevents them from becoming rain.
That’s where seeding comes in, Bates
said.
Using high-performance aircraft, pilots
soar into the clouds, either at their base or overhead, and release
the chemical compound silver iodide, which has the same basic
molecular structure as the naturally occurring ice crystals found
in clouds. By adding more crystals to the cloud of tiny droplets,
the chances of rain are multiplied. Seeding often causes a cloud
to produce six to 10 times as much rain as it would have naturally,
Bates said.
And all is done with no harmful environmental
side effects, Bates said. Silver iodide is a salt compound, and
so little is used that the traces of the chemical are hardly detectable
after the rain falls.
But not everyone is convinced that cloud
seeding is a good idea.
Dark clouds
A study released by Edwin Kessler, University
of Oklahoma meteorology professor, suggests that seeding one rain
cloud actually robs moisture from another.
Air moisture, Kessler said, is what produces
the rains, not the clouds themselves. Forcing one cloud to produce
more rain saps the air moisture, making all of the available moisture
fall to the ground in one storm system and reducing the overall
land area that receives the rain, Kessler contends.
A study published in the March issue of
Bulletin of the American Meteorological Society reported that
rainfall totals in Israel decreased on the days when clouds were
seeded. Seeded clouds produced an average of about 9 percent less
rain than unseeded clouds, according to an 18-year study on rain
enhancement by Hebrew University in Jerusalem.
Bates and Bomar point to the rainfall totals
in the Panhandle for proof of rain increases. With one of the
newer weather modification programs in place over the Lubbock
area, that city received more rainfall last year than Houston,
which typically receives at least double the rains of most West
Texas cities.
Kessler also voiced concerns about cloud
seeding worsening severe weather events, such as hail, lightning
and tornadoes.
Altering storm fronts could be potentially
dangerous, he said, voicing a concern backed by KTXS-TV meteorologist
George Flickinger.
Although careful to note that he is no cloud
seeding expert, Flickinger questioned the effects of altering
the weather.
“You really can’t predict what
you get once you start messing with the weather,” he said.
“What’s to say a seeded cloud might not produce an F3
tornado somewhere along its journey and wind up killing a dozen
people? Or that a cloud might just stop where it is, dump its
rains and cause flash flooding in a given area? Or that someone
will say that the seeding efforts wound up stealing the rains
they needed?
“Who would be responsible?”
Fear of flooding and other severe weather
can be eliminated by judicious deployment of the cloud seeders,
Bates said. Pilots check with meteorogists and don’t typically
fly when severe storm cells are overhead.
Historical data from Texas weather modification
programs suggests cloud seeding will reduce the potential for
hail, Bates said. Pilots in Kansas actually take to the air over
storms when hail is in the forecast, thereby reducing storm damage
and insurance claims, he said.
But the process won’t curb drought,
Bates and Bomar said. For cloud seeding to work, there must be
a cloud with rain potential. No clouds, as is often the case during
drought, means no rain.
Though still in the early development stages
in the Big Country, officials hope to have a cloud-seeding program
in place by May 1, 2001. Educational meetings are planned throughout
the area as the organizers move farther along in the process.
Staff writer Jerry Daniel Reed contributed
to this story.
Contact agriculture writer Bobby Horecka
at (915) 676-6737 or horeckab@abinews.com.
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Abilene Reporter-News / Texnews / E.W. Scripps Publications
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