Name: How the West Is Making It Rain, With Science
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Cloud seeding techniques boost clouds’ ability to drop precipitation by releasing particles that attract water, making it easier for water droplets or snowflakes to form.

A method of boosting snow and rainfall may help ease drought conditions in the western US.

Alex Clark is the Digital Video Producer for the NOVA Science Studio. He produces original videos for the program and leads video production training for site coordinators and students. Alex is a video journalist, cinematographer, and instructor of documentary filmmaking and he holds a degree in journalism from Columbia University. He has created TV and digital content for PBS, NBC, and NowThis. A lover of all things science, he produced and co-hosted Vox’s Emmy-nominated YouTube series, Glad You Asked.

Cloud seeding techniques boost clouds’ ability to drop precipitation by releasing particles that attract water, making it easier for water droplets or snowflakes to form.

How the West Is Making It Rain, With Science

A method of boosting snow and rainfall may help ease drought conditions in the western US.

Tech & Engineering

How the West Is Making It Rain, With Science Published April 12, 2023Alex Clark: Could this little trailer help save the drought stricken west by bringing more rain and snow to the region? That's what these engineers think. They've parked the trailer up here in the mountains of Colorado in hopes of changing the weather. And there's dozens of them just like this in use right now. Might all sound like science fiction, but it's a weather modification technique called cloud seeding. And it was first done successfully as early as the 1940s. In Colorado, some ski towns were cloud seeding as far back as the seventies, and it's also been used around the globe. China's cloud seeding program reportedly had a plan to make clouds rain before they had a chance to float over the Beijing Olympic Stadium. You can find cloud seeding from California to North Dakota. But how does cloud seeding work? To learn more, I've come to Colorado to see how seeding works up close and personal. The night before I arrived, the clouds above me were seeded.Scott Griebling: We are approaching the location of our cloud seeding generator.Alex Clark: Scott Griebling is a water resources engineer for the Local Water Conservancy district. The locations chosen for these sites have the right elevation and can reach the perfect clouds.Scott Griebling: Our district has come to the conclusion that cloud seeding and weather modification is a very safe and very cost effective way of increasing local water supplies.Alex Clark: So how do you seed a cloud?Garrett Cammans: Hey, welcome to our remote generator.Alex Clark: Garrett Cammans is president of a cloud seeding company that operates hundreds of cloud seeding sites.Garrett Cammans: And it sounds like you're terraforming or completely changing the climate of an area. But that's not that's not how it works.Alex Clark: Since clouds are basically water vapor, the idea is to release particles into the clouds that will attract water, making it easier for water droplets or snowflakes to form. They get heavier and eventually fall to earth instead of staying in the sky. This Colorado team uses a solution with a chemical called silver iodide, which, when burned, splits into billions of particles per gram.Katja Friedrich: Ice is the perfect seed or cloud seed themselves with ice crystals. Zoom Iodide is really the closest and similar structure as ice, so that's why we're using server iodide.Alex Clark: Here, cannons activates the flame. It contains the silver iodide solution mixed with propane. A series of tanks and regulators manage the pressure and exact flow rate of the silver iodide solution.Garrett Cammans: A typical storm system only drop about 10% of its moisture. We're hoping that the storm system will drop ten and a half to 11 and a half percent of its moisture.Alex Clark: Okay. But does cloud seeding actually work?Katja Friedrich: We would come out with research aircraft and with ground based radars and we would basically measure the atmosphere prior to cloud seeding and during cloud seeding.Alex Clark: The landmark Snowy project set out to discover just that. It took a pretty clever approach. A plane flying back and forth dropped chemicals into the clouds. When the team studied the resulting precipitation. They found it had snowed in a zigzag pattern matching the path of the seeding agents flow. Could it have all just been a fluke?Katja Friedrich: We were in shock and disbelief and then, of course, was say, okay, we saw it one day can we can be repeated.Alex Clark: They did the same experiment several more times as the wind blew the seeding agent. The same zigzag line of precipitation appeared, which you would never see in a natural snowfall.Katja Friedrich: This is revolutionary because we have a hard time quantifying what really comes out from from cloud seeding.Alex Clark: So at least in some situations, cloud seeding can increase precipitation but is up against challenging odds.News Reporter: Concerned about reservoir levels over the last 43 years, snowpack has only been this low or lower seven times.Alex Clark: I'm going to creek. Snow is crucial to the Rockies because as it gradually melts, water runs downstream. Replenishing bodies of water for nearby towns. That's why Colorado's Water Conservation Board partnered with the Water Conservancy district to share the costs of hiring a cloud seeding company to seed in the area. But is cloud seeding safe? Silver iodide has been used since the 19th century and photo development and also as an antiseptic and medicine. Exposure to a large amount of it could even lead to skin and eye irritation. High levels of silver iodide in one area could be toxic to organisms in our water and soil. For these reasons and others, state cloud seeding efforts are reported to federal agencies.Katja Friedrich: We want to be conscious. We don't really want to put a lot of silver into the atmosphere.Alex Clark: Over the years. Another big concern about cloud seeding has been that it could cause too much precipitation. Such as this massive flood in a small town in the UK which destroyed homes and killed more than 30 people. While circumstantial, some linked it to a nearby cloud seeding program.Katja Friedrich: Cloud seeding programs actually have to play by the rules As soon as they have a certain snow depth, they stop seeding in order to prevent floods.Alex Clark: Today, Cammans' company has hundreds of seeding sites and across the globe, several other nations are testing the technology. In fact, nearly every meteorologist I spoke with told me to get ready as they expect cloud seeding. Once a big question mark to increase in frequency. As for the potential to impact drought, it may be a long time before scientists know for sure, even if widely used, is still difficult to quantify exactly how much additional precipitation comes from seeding a cloud.We all know about the greenhouse effect, but how many of us understand why it happens? Our friends at reactions uncover what's so unique about carbon dioxide that has allowed it to transform our entire planet. Check out the link in the description and let them know NOVA sent you.

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How the West Is Making It Rain, With Science

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