By Myrna Trauntvein
Is cloud seeding effective and does it really bring more precipitation to Juab County when it is used?
“We received a letter of intent to participate in the cloud seeding program again this year,” said Byron Woodland, commission chairman.
He asked himself the question, he said, of whether or not the seeding actually worked or not.
“Do we have any data?” asked Richard Hansen, commissioner.
“There is a meeting of the Utah Water Development Corporation on September 10,” said Clinton Painter, commissioner. “Our next meeting is on September 16.”
“It costs $6,000 per annum to participate,” said Painter. “East Juab Water Conservancy District pays one half of the cost.”
He suggested the commission might want to table making a decision on whether to continue financially supporting the cloud seeding program or not until after the meeting.
Cloud seeding is a type of weather modification that aims to change the amount or type of precipitation that falls from clouds by dispersing substances into the air that serve as cloud condensation or ice nuclei, which alter the microphysical processes within the cloud.
“I would like to find out if it really works,” said Hansen.
Experiments in cloud seeding suggest that it may be possible to artificially create rainfall, Woodland said. He had seen statistics that seemed to support that the seeding worked but he had not seen data.
Rainfall occurs when supercooled droplets of water that are those that are still liquid, but are at a temperature below the usual freezing point of zero centigrade, actually form ice crystals. Now too heavy to remain suspended in the air, these then fall, often melting on their way down to form rain.
Even in dry areas the air usually contains some water. This can be made to come together and form ice crystals by seeding the atmosphere with chemicals such as silver iodide or dry ice.
The seeding works to promote rainfall by inducing nucleation so that what little water is in the air condenses around the newly introduced particles and crystalizes to form ice.
As is often the case with weather and climate, it’s difficult to carry out a controlled experiment. In areas of increased precipitation, it is difficult to know whether it would still have rained even if the clouds hadn’t been seeded.
Success has been claimed for trials in Australia, France, Spain and the US. In the United Arab Emirates, the technique is credited with the creation of 52 storms in the Abu Dhabi desert, while China boasts of having used the technology in reverse to keep the Beijing Olympic Games of 2008 dry.
“I would be interested in learning what the Utah Water Development Corporation has as evidence,” said Hansen.