Electric charge-producing device offers new avenue for creating rain

Climate change is rapidly shifting precipitation patterns around the world. As a result, water reservoirs are being depleted and already 40 percent of people on Earth are impacted by water scarcity. To help increase precipitation, many people in dry regions are turning to cloud seeding. This process typically involves flying specially equipped aircraft that burn flares with salts or silver iodide to encourage the growth of raindrops.

Introducing an alternative method for cloud seeding, Harrison et al. presented a device to increase droplet size using electric charge. The battery-powered device uses a carbon brush electrode to create a strong electric field around the device to release ions from air molecules. These ions attach to water droplets in clouds, making the droplets more likely to stick to each other when they collide.

“Charge can influence how a droplet population evolves into larger drops, sometimes reaching raindrop sizes,” said author Giles Harrison. “In the natural world, this could change how long a fog persists or whether a cloud produces rain, and/or the rate at which the droplet growth processes occur.”

In a test flight over the United Arab Emirates, the device had a highly variable current but was nonetheless able to create ion concentrations that exceeded background levels by more than two orders of magnitude. The device was designed to fit in existing flare housings mounted on specialized cloud seeding aircraft for ease in implementation.

“Our charge emitters will operate alongside the conventional cloud-seeding flares, under the control of the pilot,” Harrison said. “This makes their deployment straightforward, allowing the effectiveness of charge release to be evaluated alongside the conventional cloud-seeding methods.”

Source: “Providing charge emission for cloud seeding aircraft,” by R. Giles Harrison, Ahmad A. Alkamali, Veronica Escobar-Ruiz, Keri A. Nicoll, and Maarten H. P. Ambaum, AIP Advances (2024). The article can be accessed at https://doi.org/10.1063/5.0227533 .