Rainmakers: The drones used to seed clouds

On 23 August, Cooper Freeman had no idea clouds above his head were being filled with a silver compound in order to cause rainfall.

Neither did thousands of other residents in Homer, Alaska, who later discovered a start-up called Rainmaker conducted an experiment in that region using cloud-seeding technology.

The company, based in El Segundo California, claims it produced 19 million US gallons of water in the sky in three hours.

This approach to weather modification, now more than 80-years-old, involves using planes and drones to disperse compounds such as silver iodide into clouds to form ice crystals. Those crystals eventually become large enough to fall as rain or snow, depending on the temperatures below.

Essentially, cloud seeding speeds up the natural process of water vapor condensing inside of clouds. Gravity then pulls those crystals to the ground. The technology, though, needs ideal climate environments, such as mountainous or cold regions such as Alaska.

Freeman, the Alaska director of the Center for Biological Diversity, isn't just concerned Homer residents weren't widely alerted to these experiments. He's sceptical about what was shot into the clouds, and questions how safe it was for both residents and their habitat.

"It doesn't appear that there was any downstream monitoring to verify that this silver iodide didn't impact the environment," he says.

Freeman adds, "Having a company come in to do this seeding isn't going to solve our water woes, and it feels like a distraction from solving the urgent issues related to water conservation."