Did a cloud seeding startup really increase snowfall in parts of Utah?

States such as Utah in the western US have suffered a record snow drought, raising fears of wildfires and low water flows in the crucial Colorado River. But a start-up that releases negatively charged aerosols that can be carried up into clouds claims it has increased snowfall by 20 percent in a Utah mountain range.

Rain Enhancement Technologies compared snowfall in the La Sal Mountains and the Abajo Mountains 70 kilometers to the south over the past five dry winters. When the company operated its high-voltage ionizing array upwind of the La Sal Mountains in January, the range received 9 centimeters more snow than would have been expected given the amount of snow the Abajo Mountains received, the company says.

But researchers caution that these results may have occurred by chance, and it is too early to tell how well the technique works.

“Sky-seeding operations have been active for quite some time, and we’re offering another way to increase precipitation … but one that doesn’t involve any chemicals,” says company meteorologist Jeff Chagnon. “We also don’t have to fly into clouds… We can just flip a switch from anywhere in the world and operate for about 48 hours at a time.”

The UN warns that the world is entering an era of “water scarcity”, with up to 3 in 4 people facing water shortages or pollution. Countries like Iran, where water shortages contributed to bloody protests, have tried to induce more rain by spraying salts such as silver iodide from planes. Nine US states also have cloud-seeding programs.

But the public has often been concerned about the unknown health effects of silver iodide being released in large quantities, while conspiracy theories surrounding “chemtrails” give rise to distrust of supposed weather modification programs. Ten US states have banned or are considering banning cloud seed.

Rain Enhancement Technologies has run 100,000 volts of electricity through a coiled wire suspended between a pair of 8-meter pylons. Small aerosols such as dust, soot or salt pick up electrons when they blow near this wire, much like your feet can pick up charge when they rub against a carpet. The wind then carries some of these ionized particles up into clouds.

Water naturally condenses into aerosols in clouds to create droplets that move around and collide with each other. If they stick together, they can fall to the earth as rain. However, drops often do not attach, and therefore remain too small for gravity to overcome the uplift that holds them aloft.

But electrically charged droplets—even those with the same charge—interact to form a polarity, with the negative side of one droplet attracting the positive side of another. As droplets condense around Rain Enhancement Technologies’ negatively charged aerosols, the attraction between them increases the rate of collision and coalescence that produces precipitation, according to Chagnon.

The technology cannot drive the upward movement of air that generates clouds and rain. “But once the cloud is formed, we can get a little more water out of the cloud,” says Chagnon.

Evidence from the Cold War suggested that electrical charge can enlarge cloud droplets. A 2020 analysis found that there was 24 percent more rain over the Shetland Islands in Britain on days when radioactivity from nuclear bomb tests had ionized the air.

A Rain Enhancement Technologies trial in Oman from 2013 to 2018 increased rainfall by 10 to 14 percent, depending on the statistical analysis used, a study found. An experiment scattering negative ions by a similar group in China claimed to have increased rainfall by about 20 percent.

But the World Meteorological Organization warns that while the dispersion of salts in winter clouds has been shown to affect precipitation, the ionization approach still lacks scientific evidence.

“It is interesting that they have seen something consistent with a modification of clouds,” says Edward Gryspeerdt of Imperial College London. “But because precipitation, snowfall, precipitation is incredibly variable, there’s always a significant chance that the effect they’ve seen just happened by chance.”

The five dry years that Rain Enhancement Technologies used to set the baseline in the Utah mountain ranges may not be enough to fully account for how much difference can be seen in the snowpack across seasons, says Jeff French of the University of Wyoming.

“I would wait for further experimental studies and for several years to confirm the validity of ionization as a catalyst for additional snow,” says Ibrahim Oroud of Mutah University in Jordan.