Drought and desertification become a threat to human survival and development. Artificial rainmaking could help by improving the utilization of water resources up in the sky and bring about impressive socioeconomic benefits to societies. The ionization method was first proposed in 1890 by Nikola Tesla for weather modification. Since then, most researchers aimed at using high voltage induced ionization/discharge to create a lot of supplementary cloud condensation nuclei (CCN) to induce precipitation. However, mostly condensation was observed but with no precipitation.
Recently, Scientists at State Key Laboratory of High Field Laser Physics, Shanghai Institute of Optics and fine Mechanics (SIOM), Chinese Academy of Sciences report the first experimental observation of discharge induced artificial snowmaking in a cloud chamber. A static corona discharge was turned on inside a diffusion cloud chamber for about 25 min. between a pointed positively charged high voltage electrode and a grounded cold plate. Precipitation occurred in relatively large quantity. They attribute this phenomenon to the precipitation induced by corona induced ionic wind rather than by the ions as extra CCN. The ionic wind is essentially due to the acceleration of positive charges along the electric field lines originating from the pointed electrode towards the surface of the grounded plate. Collisions of these ions with air molecules would result in flows of air packets/parcels along the directions of the field lines.
The finding was published in Scientific Reports.
Figure . (a) A schematic diagram of the experimental setup. (b) Corona discharge under different high voltages. The electrode height was fixed at ~2.6 cm relative to the cold bottom plate.