Phys.org  May 6, 2021 Artificial charge release is an unexplored potential geoengineering technique for modifying fogs, clouds, and rainfall. To evaluate the effectiveness of the method an international team of researchers (UK, Finland) developed a small charge-delivering remotely piloted aircraft. It carried controllable bipolar charge emitters (nominal emission current ±5 μA) beneath each wing, with optical cloud and meteorological sensors integrated into the airframe. Meteorological and droplet measurements were demonstrated to 2 km altitude by comparison with a radiosonde, including within cloud, and successful charge emission aloft verified by using programmed flight paths above an upward-facing surface electric field mill. […]