California’s drought-weakened water supply is in danger. Full-scale desalination networks are a long way off, not to mention expensive, and water management remains a hotly contested issue. And that’s where the drones come in.
At least one airspace in Nevada wants to see how well unmanned aircraft can blast a chemical called silver iodide into clouds and stimulate the rain. It’s cheaper, they say, and could be more efficient than using manned planes for something called cloud seeding–a kind of weather modification originally invented by Bernard Vonnegut (Kurt Vonnegut’s older brother). If their systems prove successful, drones could play some role in generating water for a warming world.
“[Cloud seeding] is something that water managers have really started to come on board with in the last few years as drought conditions become more prevalent,” explains Dr. Jeff Tilley, director of weather modification at Nevada’s Desert Research Institute (DRI), and one of the leads on the drone research project. “Can it be a total solution? Probably not. But it can be part of what I call the toolkit; good water management has to be a part of all pieces of the pie.”
According to Tilley, there are two main ways that humans can seed clouds today. First, there are manned aircraft. In winter, pilots seeding clouds from above are better at creating ice crystals, which then become snowflakes, and fall to the ground. (Note: No one’s exactly sure why ice bonds to the silver iodide molecules, but it’s likely because they have very similar structures.) Then there’s also ground-based seeding, in which generators shoot silver iodide up into clouds from below.
But both of these methods have limitations. The first is safety: For manned operations, pilots can only seed from above the clouds, otherwise they risk flying into mountainsides. Meanwhile, ground operations are geographically spotty. Federal land is a checkerboard, so cloud seeding from the Earth can be inconsistent, and you don’t want a silver iodide generator too close to someone’s home. Drones, on the other hand, could fly in or below cloud cover at slower speeds, distributing the silver iodide relatively evenly.
And yet, drones would be no silver bullet for the West’s drought woes. Silver iodide is normally harmless, but can cause damage to people when ionized, or charged. That means seeding in the middle of stormy conditions is out of the question. Clouds also have to be in the skies in order to seed them, so cloudless days rule out seeding opportunities, too. Conditions between those extremes, however, could be ripe for the drones.
Earlier this spring, the Federal Aviation Administration certified the Nevada drone test site as operational, giving the DRI the green light to investigate drone-based cloud seeding. Tilley and his team will be researching a number of aspects of the program–like the inclusion of environmental sensors, for example, or how best to respect privacy concerns that would naturally arise from having unmanned aircraft zipping above residential areas.
Needless to say, there’s a lot of work to be done, especially in the arena of public perception. “No one’s ever really done this before,” Tilley said. “We don’t see this as something to get done from point A to point B, and then, oh, we’re done for the next 30 years. We think there will be a lot of innovation that follows.”