Seven drone flights over Alaska may have produced about 71,000 m³ of additional precipitation using just 374 g of silver iodide.
Rainmaker says it released 19 cloud-seeding flares during seven missions over the Kenai Peninsula on 22–23 August and then detected seven corresponding precipitation features on weather radar.
The company estimates the seeded clouds produced a mean 57.62 acre-feet of extra precipitation. Its central estimate spans roughly 45–65 acre-feet, while a wider statistical range runs from 41.7 to 89.35 acre-feet.
The difficult part is proving which precipitation was actually created by seeding, because weak natural rain and snow were already falling. Rainmaker tracked new radar features appearing after each release and looked for consistent timing, movement, vertical growth and repeatability. All seven missions produced a feature it attributed to seeding.
The affected footprint covered about 249.5 km², with its core receiving more than 1 mm of precipitation attributed to the operation. Rainmaker also stresses that its uncertainty range does not capture every possible source of error, including radar limitations, manual tracking and residual natural precipitation.
For the company, the experiment is a proof of concept for using drones to make glaciogenic cloud seeding more precisely deployable; it plans further refinement of the system during the coming winter.
Validation Report: Drone-Based, Glaciogenic Cloud Seeding in the Kenai Peninsula | Rainmaker Bloghttps://www.rainmaker.com/blog/alaska-validation-report