By Myrna Trauntvein
Times-News Correspondent
There will be more cloud seeding done in Juab County.
Juab County commissioners signed an agreement continuing the county's relationship with Utah Water Resources Development Corp, Delta, to provide cloud seeding services for the area of Juab County.
The county pays $6,000 annually to participate in the cloud seeding program.
"We have signed in the past without reconsidering the agreement," said Byron Woodland, commission chairman. "I would like to discuss cloud seeding with the provider."
Clinton Painter, commissioner, said he had several people approach him and request that the county consider the program and renew the contract.
Commissioners determined to sign the document and then invite the provider to come to meeting to educate them.
"They apparently have well documented information," said Rick Carlton, commissioner.
When he first began as a commissioner, the commission had the owner come to commission meeting and explain the process and the results to the commission. He said the commission could contact the owner and have him attend commission meeting to explain once again.
"The cost has been fairly consistent over the years," said Carlton. "It went up a bit when I first started as a member of the commission but it has remained the same since then."
The cloud seeding apparently helps over a wide area. Conventional wisdom suggests that, rather than decreases in precipitation downwind of target areas, increases are indicated for substantial distances, extending downwind in some instances more than one hundred miles.
Carlton said that studies have been done across North America and Canada and those studies seem to indicate that cloud seeding adds a significant amount of moisture.
It increases precipitation approximately 14 percent over areas that are not seeded, he said.
"If you're trying to increase rain or snowfall for the water supply, a 10 percent addition could do a lot. If you had a large basin like I work with, between 300,000 and 500,000 acre-feet, a 10 percent increase would equal 30,000 to 50,000 more acre-feet of water. If you can do that, it's very economically sound," said Andrew Moseman, in Scientific American.
Clouds, whether in summer or winter, are not perfectly efficient at producing precipitation. There's some part of a storm that's much less than 100 percent efficient in turning clouds into precipitation.
In winter, the problem is that there aren't sufficient ice crystals. If droplets fall in liquid form, they generally evaporate. The idea is to add ice-forming particles.
The structure of crystals made from silver iodide is very similar to that of ice. The lattice structure at the molecular level is extremely close. That's why ice wants to bond to it, said Moseman.
The initial discoveries were in the 1940s, with substances like silver iodide. Bernard Vonnegut, the older brother of the novelist Kurt, uncovered silver iodide's weather-modifying properties as a researcher for General Electric in 1946.
Utah is the second driest state in the nation. Winter cloud seeding projects have been conducted for several of the mountain ranges within the state. One project in particular lends itself favorably to investigation of downwind effects. This is the Central/Southern Utah project which has been operated during the winter seasons from 1974 through the present.
The mountain ranges in central and southern Utah are oriented basically north-south. Barrier crest heights average approximately 9,000 feet in elevation, with many peaks above 10,000 feet and a few above 12,000 feet.
Most recently, an evaluation covering 25 seeded seasons (Mark E. Solak, David P. Yorty and Don A. Griffith, North American Weather Consultants, Inc., Sandy) reported a 14 percent increase. They indicated a14 percent average seasonal increase corresponds to an average 1.39 inches of additional snowpack water content across the approximately 10,000 square mile target area.
Independent analyses of the project conducted by the State of Utah Division of Water Resources (Stauffer, N.E. and K. Williams, 2000: Utah Cloud Seeding Program, Increased Runoff/Cost Analyses. Utah Dept. of Natural Resources, Division of Water Resources, Salt Lake City) and (Stauffer, N.E., 2001: Cloud Seeding--The Utah Experience. J. Wea. Mod., 33, 63-69) provided similar estimates of percentage increases and also addressed the resultant increase in augmented streamflow.
Stauffer estimates the average annual increased runoff from the Central/Southern seeding project alone at about 142,500 acre feet. Thus, plausible/credible, if not precise, estimates for the magnitude of the seeding effects within the high elevation target area, and the resultant runoff, have been established.
In an earlier study, average-value downwind effects for the seeding project were investigated over 13 seeded seasons for a single downwind group of sites.
That analysis indicated an average 15 percent increase in precipitation for the seven-site group extending a maximum of 75 miles downwind. In the current work, the study capitalizes on the fact that the array of downwind sites is sufficiently dense for assessment of the estimated effects as a function of downwind distance (as far as 150 miles) and enjoy the benefit of a larger number of seeded seasons.
