7/23/02

They don’t like to be called rain-makers, but a company in North Dakota specializes in seeding clouds with particles of silver iodide to increase precipitation.
Cornfields throughout the region are suffering, farm ponds have evaporated and wells have dried up. So isn’t it time to call in cloud-seeders to fly into clouds and disperse silver iodide?
It’s not that simple, said Bruce Boe, director of meteorology for Weather Modification Inc., a Fargo, N.D. company. WMI has become a world leader in the areas of hail suppression and precipitation augmentation over the past 40 years, Boe said.
Some states have laws that regulate cloud seeding. Local governing bodies must conduct public hearings to address concerns and to get permission to use public funds before they can hire a cloud-seeding company, Boe said.
“You can’t just say, ‘Oh cool, I’m going to go up and seed some clouds this afternoon,’” said Boe, whose crops on his 80-acre farm are suffering from a drought.
WMI has conducted cloud seeding programs in California, Nevada, New Mexico, North Dakota, Oklahoma and Texas, as well as Argentina, Greece and Mexico.
If officials from the region did hire Weather Modification Inc., pilots would fly over or into billowing, white, puffy clouds known as cumulus clouds.
When ignited inside a cloud, the flares release smoke comprised of silver iodide and salt.
The cloud’s updraft would carry the iodide-salt particles to the altitude where supercooled water is located. This would cause or speed up the formation of ice that nature is lacking, Boe said.
Once ice forms, it falls and quickly melts, turning into rain.
Timing is important because the average cumulus cloud stays in existence only 15 to 30 minutes.
Of course, a thunderstorm can remain intact for hours as it moves from county to county.
“We don’t make rain,” Boe said. “We make the cloud live longer and improve the efficiency of the cloud. We see a 20- to 30-percent increase in the amount of actual rain falling from seeded clouds. I suggest we think about cloud seeding long-term before the drought sets in. When we get into a high-pressure drought situation, we don’t have many good clouds to work with.”