WEATHER Does cloud seeding work? Council calls for research

Cloud seeding is done in 24 countries and 10 states.
BISMARCK, N.D. (AP) -- The debate has been going on for decades, in legislatures, in county board rooms and in farm fields: Can the clouds be changed to make rain?
Hans Ahlness says yes. Dan Flor says no.
The National Research Council says it's time to find out.
No convincing evidence
The council, an arm of the National Academy of Sciences, said in a recent report that though clouds across the globe have been seeded for 60 years to increase rainfall and reduce hail, there is no convincing evidence it works.
The council is calling for a national research effort into weather modification -- cloud seeding now done in some form in 24 countries and 10 states, including North Dakota.
Ahlness, vice president of operations for Fargo-based Weather Modification Inc., which seeds clouds in a number of states and countries, doubts more research will ever end the debate, but he thinks it's a good start.
Storm clouds are seeded by sprinkling them with tiny crystals of silver iodide to promote moisture circulating in the tops of the clouds. The theory is that the developing ice crystals melt as they fall, producing rain.
Snow increase
A Denver cloud seeding operation was credited last year with increasing the amount of snow in one county with four ski areas.
Flor, who ranches near Marmarth in southwestern North Dakota's Slope County, sees no proof of it.
"There's no proof that it's ever produced any more rainfall. The hail insurance premiums don't reflect that it decreases hail," he said.
Five North Dakota counties and part of Slope County take part in the Cloud Modification Project, which is operated and partially funded by the state Atmospheric Resource Board.
This past summer, cloud seeding planes spent about 675 hours in the air over those counties, board director Darin Langerud said. The total cost of the program was about $600,000, with the board paying about one-third of the cost and the counties the rest.
Langerud said the cost prevents other counties from signing up, but a lack of hard evidence that cloud seeding works also is a factor.
"If you hold it to ... scientifically credible proof, it is true that a lot of aspects of cloud seeding have not met that standard," he said. The government, he said, has not adequately funded research to help states meet that standard.
Stolen rain?
In the early 1990s, Montana farmers worried that cloud seeding over eastern Montana was stealing their rain. The Montana Legislature passed a law requiring an expensive environmental study and a $10 million bond before any cloud seeding could take place, effectively putting a stop to cloud seeding in 1993.
Even years of drought have not changed the minds of some Montana farmers.
"We're way better off right now than we were in the 1980s, when [cloud seeders] were in here," said Bernard Pease, who farms near Lambert, Mont., to the west of North Dakota's McKenzie County.
"If these guys are so great, there would be people knocking on the door to bring them in."
Langerud said cloud seeding often is not the answer to ending a drought because the clouds have to be there to seed.
"You can't make it rain out of a clear, blue sky," he said.
Better research programs and communication might help convince people of the benefits of cloud seeding, Ahlness said.
"People tend to be pretty polarized on the issue," he said. "When things are going badly in farming ... you're always looking for something that's causing your misfortune. The weather is always a lightning rod for that ... and we're out there fiddling around with it."
The National Research Council said the United States invested more than $20 million a year in weather modification research in the late 1970s, but now spends less than $500,000 a year. It said only a handful of research programs exist worldwide.