UW Researcher Leads Study of First Quantifiable Observation of Cloud Seeding

Cloud-seeding graphic via Science Matters

From the University of Wyoming:

A University of Wyoming researcher contributed to a paper that demonstrated, for the first time, direct observation of cloud seeding — from the growth of the ice crystals through the processes that occur in the clouds to the eventual fallout of the ice crystals that become snow — and how the impacts could be quantified.

The research, dubbed SNOWIE (Seeded and Natural Orographic Wintertime Clouds — the Idaho Experiment), took place Jan. 7-March 17, 2017, within and near the Payette Basin, located approximately 50 miles north of Boise, Idaho. The research was in concert with Boise-based Idaho Power Co., which provides a good share of its electrical power through hydroelectric dams.

“No one has ever had a full comprehensive set of observations of what really happens after you seed the cloud,” says Jeff French, an assistant professor in UW’s Department of Atmospheric Science. “There have only been hypotheses. There has never been a set of observations from one campaign that shows all the steps that occur in cloud seeding.”

French credits modern technology, citing the use of ground-based radar, radar on UW’s King Air research aircraft and multiple passes of the mountain range near Boise with making the detailed cloud-seeding observations happen. Despite numerous experiments spanning several decades, no direct observation of this process existed before SNOWIE, he says.

French is the lead author of a paper, titled “Precipitation Formation from Orographic Cloud Seeding,” which appears in the Jan. 22 (today’s) issue of the Proceedings of the National Academy of Sciences (PNAS), one of the world’s most prestigious multidisciplinary scientific journals, with coverage spanning the biological, physical and social sciences.

Other contributors to the paper were from the University of Colorado-Boulder, University of Illinois at Urbana-Champaign, the National Center for Atmospheric Research (NCAR) and Idaho Power Co.

“SNOWIE was a great collaborative effort, and it shows the value of private, public and academic partnerships,” says NCAR scientist Sarah Tessendorf, a co-author of the paper.

Tessendorf notes that SNOWIE grew out of research that Idaho Power Co. had conducted with NCAR to improve its cloud-seeding program. This included the development of high-resolution computer modeling approaches to simulate cloud seeding, enabling researchers to better evaluate its impacts.

“This research shows that modern tools can be applied to long-standing scientific problems,” says Nick Anderson, program director in the National Science Foundation (NSF)’s Division of Atmospheric and Geospace Sciences, which funded the study. “We now have direct observations that seeding of certain clouds follows the pathway first theorized in the mid-20th century.”

Cloud seeding is a process by which silver iodide is released into the clouds, either from the air or via ground-based generators. In the case of the SNOWIE Project, the silver iodide was released by a second aircraft funded through Idaho Power Co., while the UW King Air took measurements to understand the impact of the silver iodide, French says.

In all, the UW King Air made 24 research flights or intense observation periods (IOPs) lasting 4-6 hours each during SNOWIE. Of those IOPs, cloud seeding occurred during 21 of the flights. During the last three flights, Idaho Power had to suspend cloud seeding because there was so much snow in the mountains already, French says.

While a good deal of research took place aboard the King Air, much of it also occurred on the ground. Numerical modeling of precipitation measurements was conducted using the supercomputer, nicknamed Cheyenne, at the NCAR-Wyoming Supercomputing Center. The numerical models simulated clouds and snow precipitation — created in natural storms and with cloud seeding — over the Payette Basin in Boise. The numerical models also allow researchers to study future storm events where measurements have not been obtained in the field.

“Midterm, it will help with those simulations we are running on Cheyenne,” French says. “Long term, we can answer questions with this data and simulations on how effective cloud seeding is in orographic clouds, and what conditions one can expect cloud seeding to be effective.”

Throughout the western U.S. and other semiarid mountainous regions across the globe, water supplies are fed primarily through snowpack melt. Growing populations place higher demand on water, while warmer winters and earlier spring reduce water supplies. Water managers see cloud seeding as a potential way to increase winter snowfall.

“Ultimately, water managers and state and federal agencies can make the decision whether cloud seeding is a viable option for them in terms of adding additional water to their supplies in addition to snowpack in the mountains,” French says.

From Science Magazine (Angus Chen):

…despite decades of cloud seeding operations, proof that the technique works outside miniaturized clouds created in the lab has been elusive. One reason: Instruments of decades past couldn’t measure water droplet size in clouds in real time. Without knowing how a cloud evolves after seeding, scientists were unsure whether the silver iodide was doing anything at all. Another: The chaotic nature of weather makes controlled, natural experiments almost impossible. “Once you seed, you’re contaminating the cloud. You can’t repeat the experiment because you’ll never have the same atmospheric conditions again,” says Katja Friedrich, an atmospheric scientist at the University of Colorado in Boulder.

But newer instruments convinced Friedrich and her colleagues that the time was ripe for another approach—and the National Science Foundation and Idaho Power provided the funding. The team took its experiment to the mountains of southwestern Idaho, where it waited until supercooled clouds appeared in the sky. At temperatures of 0°C to –15°C, they are cold enough to freeze, but are at low odds of doing so.

When the right clouds came along, the team sprang into action. It launched one aircraft that made laps between two ground-based radars, dropping canisters that spread silver iodide into the clouds. The same plane also flew through the cloud while streaming silver iodide from its wings. Another plane loaded with cloud measuring equipment paced a perpendicular path to take readings.

At first, there was nothing. “The radar can only see [water] particles that are big enough, and these clouds had tiny droplets not detectable by radar,” Friedrich says. “Suddenly, we saw lines appear. It was really astonishing.” The zig-zagged lines matched the flight path of the first plane. Within these lines, the cloud’s water particles were getting bigger as they hit the silver iodide and froze. After a couple of hours, the snowflakes had grown from a few microns in diameter to 8 millimeters in diameter—heavy enough to fall to the ground, Friedrich and her colleagues report today in the Proceedings of the National Academy of Sciences. “We were super, super excited. Nobody had seen that before,” she says.

The experiments have also been met with enthusiasm from cloud seeding companies. “Those of us working on cloud physics for a long time have felt that [cloud seeding] was working,” says Bruce Boe, a meteorologist at cloud-seeding company Weather Modification in Fargo, North Dakota. “This verification and incontrovertible evidence this is occurring is really, really nice for us.”

Still up for study is whether the approach is economical. “Does it make enough snow to make an impact on a water budget?” Friedrich wonders. “We still have to answer those fundamental questions.”

Clouds with a Silver Lining: Seeding Storms to Boost the #ColoradoRiver — @COindependent #COriver

A cloud seeding generator near the Winter Park ski area in Colorado. (Desert Research Institute (DRI))

From The Colorado Independent (H20 Radio):

Clouds with a Silver Lining: Seeding Storms to Boost the Colorado River

In much of the West, demand for water is projected to outpace supply, especially in the Colorado River basin, which provides drinking water to over 40 million people. There are various strategies to close the gap–some controversial like building new reservoirs and others more widely accepted like conservation.

But what if you could just wave a magic wand and make it rain or snow? It’s not impossible and in fact, it’s been going on in the West for years.

It’s called weather modification, better known as “cloud seeding.” With a changing climate and drier future, many are looking to the technique to boost snowpack in the mountains to meet growing water needs. More snow, even a small percentage can mean more runoff—and more water to cities and farms.

Back in the fall we drove with Joe Busto from the Colorado Water Conservation Board out of Fraser, Colorado, in the Rocky Mountains to see a cloud seeding operation firsthand—and meet some of the people involved. Busto says they’re trying to “put extra snow in the bank where you need it for water supplies” and that cloud seeding has been shown to add anywhere from 5 to 15 percent to the snowpack.

Snow pit at Winter Park — sampling for silver iodide. Photo via the Desert Research institute.

There are about 40 total sponsors of cloud seeding in Colorado, including regional water districts, the state of Colorado, local water districts, cities, towns, counties, and nine of the state’s 28 ski areas.

With us in the car is Maria Pastore, who represents some of those entities that range from Denver Water and Colorado Springs Utilities to ski areas like Winter Park, which we’re not too far from as we drive. For a state with much tension around moving water across the Continental Divide, Pastore says cloud seeding is being embraced by both sides. She says they have a large group of collaborative sponsors, and cloud seeding is probably one of the arguably least contentious programs for the West Slope and East Slope partners.

Pastore’s group works with ski areas for cloud seeding because you get more bang for the buck. They’re already located in places that typically get a lot of snow—and they provide a recreational benefit. After folks have schussed or snowboarded across it, the snow will melt and flow into the tributaries of the Colorado River to become drinking water and to turn turbines in hydroelectric dams.

We arrive at a spot that could pass for a nice campsite. Parked on it is a small camouflage-painted trailer with a twenty-foot mast sticking up in the air—and a barrel on top. Waiting for us by the trailer is Jeff Dean of the Desert Research Institute, or DRI. Dean and his team are at this site to get the cloud seeding equipment, called the generator, ready for the season ahead. So how does cloud seeding work?

Dean explains that cloud seeding is done by adding extra dust to the air. A typical cloud will only drop maybe five percent of its available moisture. They’re not very efficient. Inside every cloud droplet and every snowflake there is a piece of dust—nuclei that started the process. In cloud seeding, they’re just introducing a little bit more of that dust. They do that by burning silver iodide, which goes up in the air to start the growth of a crystal that eventually will turn into a snowflake.

DRI has meteorologists watching several factors like wind speed, humidity, and temperature to identify the perfect moment to fire up the generator to hit their intended target, which in this case is the Winter Park ski area and Denver Water’s drainage.

Dean is out here with us to demonstrate how they start up the equipment. With a tap on his laptop the generator begins to hum. Dean could have been in his office in Reno or on a beach in Maui to activate the system. We watch inside the barrel and after a few seconds a bright yellow, robust flame appears, which indicates that the silver iodide solution is starting to burn. Dean says that last year this generator produced 22 inches of snow for the ski area.

So how do they know it wouldn’t have snowed anyway? They assess that by looking for traces of the silver iodide in the snow. DRI did an analysis at the Winter Park ski area where they went halfway up the lifts and did a full profile all the way to the ground by inserting test tubes every ten centimeters. They then weighed the samples and did a chemical analysis. They found trace amounts of the silver, which according to the state of Colorado, are at extremely low concentrations and not harmful.

The cloud seeding program isn’t just being sponsored by providers in Colorado. Downstream users in other states who depend on a good Rocky Mountain snowpack are also on board. Joe Busto says that after the drought in early 2000s, it was bad in Colorado, but the state rebounded quickly because reservoirs are next to the mountains. But the lower basin states downstream on the Colorado River—Arizona, California, and Nevada—came knocking on the door and said, “Lake Powell and Lake Mead are drying out…”

The result was a partnership among the Southern Nevada Water Authority that serves Las Vegas, the Central Arizona Project, and six agencies in California including the mega-one in L.A. All now help fund cloud seeding in Colorado.

So while recent storms are thrilling skiers, a good base on the slopes this year may also contain a silver lining for water users hundreds of miles away.

Detailed Colorado River Basin map via the U.S. Bureau of Reclamation.

Cloud-seeding is gaining acceptance

From the SummitDaily (Jack Queen) via The Aspen Times:

[Larry] Hjermstad and his company, Western Weather Consultants, now run cloud seeding programs across the state, including in Summit County.

For decades, local ski areas have paid him to send plumes of silver iodide up to their slopes when opportune storms approach, squeezing out a couple of extra inches of snow each time.

In recent years, however, water managers on the Front Range and even states further down the Colorado River have started to pitch in some of the $250,000 to $300,000 it costs to run the program in the Summit County area, hoping the extra snow will flow into their water system when it melts.

Here, in the Central Colorado Mountains River Basin, the company operates about 36 cloud seeding generators. They’re small, almost homebrew-looking devices that burn a solution of inert silver iodide and send it into the atmosphere.

Some of the generators are on private land, and when Western Weather Consultants detects an optimal storm coming, it sends instructions to the landowners to fire them up. It varies, but Hjermstad says the process can boost snowfall by as much as 25 percent…

SNAKE OIL OR SCIENCE?

The concept of cloud seeding has been around since the 1940s, when Bernard Vonnegut (brother of author Kurt) discovered that silver iodide could produce ice crystals when introduced into cloud chambers.

In those heady days, cloud seeding was heralded as a way to produce rain where there was none, boosting crop yields and filling reservoirs to the brim.

That was a wild overstatement, and cloud seeding’s reputation suffered for it…

Studies in Australia and Israel have debunked the idea that airplanes spewing silver iodide willy-nilly will do much of anything. But a targeted approach that hits the right clouds at the right time high in the mountains has gained scientific currency in recent years.

Rio Grande Roundtable meeting recap

Cloud-seeding graphic via Science Matters

From The Alamosa News (Ruth Heide):

Although there are currently no cloud seeding operations in the San Luis Valley, some folks believe this might be a good place for it.

Joe Busto, who oversees weather modification permits for the Colorado Water Conservation Board, gave the Rio Grande Roundtable group a crash course on cloud seeding during its Tuesday meeting. The Valley-wide water group funds many water related projects in the Rio Grande Basin from ditch repair to reservoir rehab. The group was not asked for funding at this time.

Busto said that another form of weather modification, hail cannons, previously operated in the San Luis Valley under a permit with Southern Colorado Farms, but the agricultural operation discontinued the practice.

Cloud seeding occurs all around the region from Texas to North Dakota, Busto stated.

Many of the cloud seeding operations in Colorado are associated with ski areas such as Vail, Crested Butte and Breckenridge, Busto explained. Others are connected to water districts. There are currently 110 machines in the state. He described the primary catalysts as either silver iodide, which is expensive but effective (and not harmful to the environment), or propane, which is cheaper.

Before setting up a machine, plume dispersion tests are conducted to determine how the winds are blowing and from what direction so the cloud seeding operation can be set up to provide the most good.

Operations are also the most effective when machines are set up at higher elevations, Busto explained.

Roundtable member Travis Smith asked, “Is the Rio Grande ready to start participating in a winter time cloud seeding program?”

Roundtable member Charlie Spielman said he saw this as a solution to the imbalance between water supply and demand.

“Cloud seeding is the best opportunity within our reach of making a real dent in that supply/demand gap,” he said.

He encouraged “getting a program going here … Let’s put something into this because I think this is our best chance.”

Busto said he believed a lean cloud seeding operation could be put in place for about $60,000 a year. He said he believed there could be many benefits to this area as well as downstream.

#ColoradoRiver: The @CWCB_DNR is installing a ceilometer in Winter Park #COriver

Winter Park via MyColoradoLife.com.
Winter Park via MyColoradoLife.com.

From The Sky-Hi Daily News (Travis Poulin):

At their October 4 meeting, the Winter Park Town Council passed a motion to allow a ceilometer to be installed on the roof of the Winter Park Town Hall. . A ceilometer is a device that uses a laser to determine the height of a cloud base.

The town received a request from the Colorado Water Conservancy Board (CWCB), Denver Water and Winter Park Resort to place the device on the Town Hall building to aid them in their cloud seeding program. It will detect multiple layers of cloud height as well as measure the liquid water available in the clouds. The ceilometer will allow them to provide better forecasting for the cloud seeding program.

In addition to the cloud seeding program, this device will be available to pilots flying into Grand County. The pilots can determine the base elevation of the clouds as they approach the runway at the Granby/ Grand County Airport. The ceilometer is approximately four feet tall and would be attached to an existing concrete pillar.

The ceilometer will need electricity and Internet service. The electricity usage is approximately 5 amps per month (about 55 cents per month). The data usage is approximately a half a megabyte per month. The additional Internet service would not require upgrades as the current system has adequate space.

The Winter Park Town Council, CWCB, Denver Water, and Winter Park resort are now in the process of drafting a Memorandum of Understanding (MOU) for the installation of the ceilometer. The council also determined they will need a lease agreement for the project.

CLOUD SEEDING IN GRAND COUNTY

There are currently two cloud seeding generators in Grand County—one to the north of the Younglife camp at Crooked Creek Ranch, and the other near Churches Park in Fraser. The generators are remotely operated and controlled from Reno, Nev. They have been in place since 2009.

The Desert Research Institute (DRI) runs the cloud seeding program. According to their website, DRI currently has five cloud seeding operations: the San Juans (Mancos) Project, the San Miguel (Telluride) Project, Tahoe and Truckee basins, Walker Basin, and the Winter Park/ Denver Water Project. The purpose of the program is to augment snowfall in mountainous regions that supply water to northern and southern Nevada, and increase the snowpack and resultant runoff from the targeted basins.

According to DRI website, ground-based generators are used to burn a solution of silver iodide, sodium iodide, salt and acetone to release microscopic silver iodide particles which can create additional ice crystals, then snow, in winter clouds. Weather conditions are selected to optimize fallout in targeted basins. Generators are remotely operated by telephone landline, by radio or by other types of wireless communication. A seeding aircraft is frequently used to augment ground seeding operations. The aircraft releases AgI from wing-mounted solution burners. Dry ice is also used occasionally to seed shallow cloud systems, including fog over airports.

According to the website, benefits vary with the seasonal frequency of suitable weather opportunities. Research results have documented precipitation rate increases of a few hundredths to about two millimeters per hour due to ground-based seeding during the proper weather conditions. Based on the rate increases, estimates of augmented snow water from the DRI seeding program have varied from 20,000 to 80,000 acre-feet annually over the past 15 years of operation.

Seasonal percentage increase estimates have varied from two percent to ten percent The cost of augmented water, based on the annual cost of the program, has ranged from $7 to about $18 per acre-foot, according to DRI.

Cloud-seeding graphic via Science Matters
Cloud-seeding graphic via Science Matters

#ColoradoRiver: Remote-operated cloud seeder being installed above Dolores — KOAA.com #COriver

instumentationcloudseedingresearchcolorado

From the Associated Press via KOAA.com:

A remote-operated cloud-seeding generator is being installed in the mountains above Dolores in an attempt to improve snowpack and runoff into McPhee Reservoir.

Cloud seeders emit plumes of silver iodide into winter storm clouds to coax additional precipitation from clouds.

There are about 30 cloud-seeding generators stretching in an arc from Telluride to Mancos to Pagosa Springs. Most of the units are 40-year-old designs and require an operator to turn them on and off when conditions warrant.

The Cortez Journal reports that the Dolores Water Conservancy District has partnered with the Idaho Power Co. and Colorado Water Conservation Board on the project. Idaho Power has developed a more efficient remote-controlled generator that can be placed in locations higher in the mountains and closer to the clouds they seed.

Cloud-seeding graphic via Science Matters
Cloud-seeding graphic via Science Matters

Cloud seeding: “It can’t replace dams or conservation” — Joe Busto

Cloud-seeding graphic via Science Matters
Cloud-seeding graphic via Science Matters

From the Watch (Stephen Elliott):

[Andy VanDenBerg] is one cog in a regional cloud seeding program that purports to increase wintertime snowfall over Telluride by as much as 15 percent; he’s one of the dozen or so landowners from Dolores to the southwest to Disappointment Creek and Saltado Creek further north who have allowed Durango-based Western Weather Consultants to install cloud-seeding generators on their properties, and are paid to operate them when a promising storm system moves into the area.

“It doesn’t make much money. It’s kind of a waste of time and an inconvenience,” VanDenBerg said. “But there’s a chance it works.”

It’s difficult — nearly impossible — to prove wintertime cloud seeding’s efficacy, but that hasn’t stopped the Telluride Ski & Golf Company, Dolores Water Conservancy District, Southwestern Water Conservation Board, Colorado Water Conservation Board, California Six Agency Committee, Central Arizona Water Conservation District, Southern Nevada Water Authority and Metropolitan Water District of Southern California from funding cloud seeding in the Upper San Miguel Drainage Basin, specifically on the Telluride Ski Resort.

“We’re in a 15-year drought and reservoirs are down, so we’re trying to help prevent them from going down further, and maybe bring them back up a little bit,” said Bill Hasencamp, Colorado River Resources Manager for the Metropolitan Water District around Los Angeles.

Hasencamp, like VanDenBerg, can’t be sure cloud seeding works (or at least how well it works), but his agency still enthusiastically funds the program. “There’s a general feeling that it increases snow, but no absolute proof. That’s the tough part: It’s very difficult to tell exactly,” he said.

All of the water managers involved in the Colorado cloud seeding program cite a study from Wyoming when discussing the effectiveness of cloud seeding. The study, conducted by the National Center for Atmospheric Research and several other organizations, was completed in 2014 and compared two mountain ranges in the state: the Medicine Bow and the Sierra Madre. For 10 years, researchers randomly seeded storms in one of the ranges, but not the other, in an attempt to discover if cloud seeding increased snowfall.

That study indicated a 5-15 percent snowfall increase, presumably due to cloud seeding.

“There’s not really any downside to [cloud seeding],” said Joe Busto, cloud seeding program manager with the CWCB. “It doesn’t do a lot, just a few inches more here and there. It can’t replace dams or conservation; it’s just a thing we do every year and we get a little more and that’s all it is.”

[…]

Water managers could conceivably seed clouds anywhere along the Colorado River Basin but have decided to partner with ski areas to boost recreational economies and take advantage of the funding those ski areas are willing to put up for the program.

“Although the state supports [cloud seeding], it’s not just because we want to support all the ski areas. This is a new water source, but it has the great benefit of helping out our recreational economy in Colorado,” said April Montgomery, a San Miguel County-based representative on the CWCB. “This is also a huge benefit to Norwood and the West End. We’re producing more water for our Telluride headwater reservoir, and that’s all going down to the lower ends of the San Miguel, into the Dolores, into the Colorado.”

As reservoirs along the Colorado River, including Lake Powell and Lake Mead, have dried up during the past few years, water managers downstream have turned to more experimental ways to keep them full, or at least less empty. Busto at the CWCB said the out-of-state agencies have contributed nearly $2 million to the Colorado cloud seeding program since 2007.

“The reason why the state is involved in cloud seeding is because it’s the cheapest form of new water. If you look at other ways of creating new water sources, you’re looking at desalinization or you’re looking at giant reservoir systems and new diversion systems. That costs so much money,” Montgomery said. “Our snowpack is the largest reservoir we have and if we can increase our snowpack, we are basically creating this giant reservoir that we can use later.”

[…]

But cloud seeding raises questions. Does silver iodide negatively impact the watershed once it falls out of the clouds? If we coax precipitation from clouds over Telluride, does that mean less will fall on other communities?

Cloud seeding proponents answer a resounding “No” to both questions.

The Wyoming study found silver concentrations in the water after cloud seeding in the parts per trillion range, and in the parts per billion range in soil, “about three orders of magnitude less than values considered hazardous to environmental system or human health.”

“Silver iodide doesn’t dissolve into the water,” Montgomery said. “One reason I’ve been able to embrace this technology is, as we improve and we’re being more efficient and effective with it, we’re not just throwing this up into the atmosphere.”

“This is something that doesn’t bioaccumulate,” Busto added. “When a chemical gets in the fish, then the eagles get it… That’s bioaccumulation. It’s a concern, but [silver iodide] won’t do that.”

As for cloud seeding’s effect on nearby areas, Western Weather’s founder Larry Hjermstad, who has been working in weather modification for four decades, said seeding merely takes advantage of an opportunity in a storm.

“One of the big concerns is, if we’re putting more precipitation in one area, it’s at the expense of another area. The answer is no; we’re creating a slightly better storm system,” he said.

Busto added that winter storms are typically large, often 200 miles long or more, and contain huge amounts of moisture, only a small amount of which will ever fall as precipitation. So when cloud seeding urges slightly more of that moisture out of the clouds, the vast majority of a storm’s moisture remains to fall elsewhere or stick around in the cloud.

“To say you took all the water out of a system that was 200 miles long is really a stretch,” Busto said. “Did you steal that [precipitation] from someone else? No, I don’t think so.”

The Wyoming study concurred, finding that the “downshadow effect,” or the impact of cloud seeding on areas outside the seeded area, was negligible.