Question

How does it become possible to cause artificial rain by spraying silver iodide on the clouds?

Answer 1

• Clouds are colloidal in nature and carry some charge. For rainfall to occur, two oppositely charged clouds must combine.
• It is possible to cause artificial rain by throwing electrified sand or spraying a sol carrying charge opposite to the one on clouds.
• Silver iodide $AgI$ being an electrolyte, helps in the coagulation of colloidal water particles, which forms bigger droplets of water and thus led to artificial rain.

$AgI$ is usually sprayed using aeroplane or remote controlled rockets.