It is not uncommon to find answers wherever people can find a disaster. The catastrophic floods in Texas are no exception.
There are many potential reasons why so many people have been killed by the rapid rise of water, but what some have settled is a practice known as cloud seeds. They claim that the storm has caused more rain than otherwise would have been due to a cloud sowing startup known as Rainmaker. However, the data does not support concerns.
Katya Friedrich, an atmospheric scientist at the University of Colorado Boulder University, said that although it was true that the rainmakers were operating in the area a few days before the storm, “it had nothing to do with the cloud seed,” despite online chatter.
“It's a complete conspiracy theory,” said Bob Lauber, professor of atmospheric science at the University of Illinois.
Cloudseed is nothing new. It has been practiced since the 1950s, Rauber said. It works by spraying small particles onto clouds made of silver iodide.
Silver iodide grains mimic the shape of ice crystals, causing droplets to freeze to ice when they hit water droplets that remain liquid under the freezing point. That freeze is important, Lauber said. Ice crystals grow in size faster than supercooled water droplets. This means that it is more likely to capture enough water vapor to be large enough to fall off the clouds. If they remained as supercooled water, they could eventually evaporate.
Only clouds with sufficient amounts of super cooling water are good candidates for cloud sowing.
In the United States, most cloud seed occurs in winter near the western mountain ranges. There, when the mountains push the air high, clouds form, cooler and water vapor condenses. If properly sown, such clouds release some of its water like snow, which is raised as snowmen and forms a natural reservoir that recharges the artificial reservoir held behind the dam during the melting of spring.
People have sown clouds for decades, but the impact on precipitation is a new field of research. “Until recently there was really no technology to assess it,” Rauber said.
In early 2017, Rauber's Friedrich and their colleagues set up a store in Idaho to carry out one of the most in-depth studies of cloud seed to date. The clouds were sown three times for a total of 2 hours and 10 minutes. Adding about 186 million gallons of additional rain was enough.
That may sound a lot, and for drought-hit Western states, it can make a difference. Idaho seeds many clouds throughout the winter, increasing the amount of water collected behind the dam, allowing it to generate electricity throughout the year. “Their data shows it's cost-effective for them,” Lauber said.
However, compared to the big storm, 186 million gallons are peanuts. “When we talk about that huge storm that occurred in the flood (Texas) we're talking about the atmosphere that literally processes trillions of water,” he said.
If the rainmaker had an impact on the storm, it would have been a barely rounded error, as it was so tiny. But the reality is not that.
First of all, the company had sown nearby clouds a few days before the storm struck. “The air that had been in the area two days ago was probably somewhere in Canada by the time the storm hit,” Lauber said.
Second, it is not clear whether cloud sowing is effective in cumulus clouds that occur in Texas in the summer. They do not respond the same to the cloud seeds, unlike the orograph clouds that form near mountain ranges. One tends to be short-lived and not produce much precipitation.
Cloudceder may try to try more caxes from them anyway, but “the amount of rain coming out of those seed clouds is small,” Lauber said.
What lasts long enough? “The clouds as deep as thunderstorms have a good natural process,” he said. “These clouds are very efficient. They don't do anything to seed these clouds.”