Mint Explainer: Why cloud seeding is easy to propose but hard to implement

livemint.com:

paper, "an experiment on artificial stimulation of rain using a warm cloud seeding technique was undertaken in three nearby climatologically similar regions, Delhi, Agra and Jaipur in northwest India". Many countries now use this technology, including India and China, but implementation is easier said than done. It has certain limitations, not to mention a likely adverse impact on the environment.

IIT-Kanpur has been working on cloud seeding for over five years but the technology is yet to go mainstream. The institute successfully conducted a test flight (with a Cessna aircraft) for cloud seeding on 22 June. However, it was raining that day, and "the intent was to check the systems and collect data, not to seed the cloud and make it rain", according to an article in Vox Populi.

Cloud seeding involves the introduction of certain substances into the atmosphere such as silver iodide, potassium iodide, or even liquid propane (which expands into a gas), that act as a core around which water vapour can condense, forming droplets or ice crystals. As these particles combine and grow bigger, they eventually fall to the earth as rain or snow. Techniques include silver iodide seeding, which involves dispersing silver iodide into clouds, promoting the formation of ice crystals.

Potassium iodide and potassium chloride seeding similarly encourages ice-crystal formation in clouds. Silver iodide, which the Chinese use, is effective because its form is similar to that of ice crystals. Calcium chloride is often used in warmer regions, and researchers have also used sodium chloride (common salt) for cloud seeding.