Cloud seeding is the process of spreading either dry ice (or more commonly, silver iodide aerosols) into the upper part of clouds to try to stimulate the precipitation process and form rain. Since most rainfall starts through the growth of ice crystals from super-cooled cloud droplets (droplets colder than the freezing point, 32 deg. F) in the upper parts of clouds, the silver iodide particles are meant to encourage the growth of new ice particles. The history of cloud seeding has seen uncertain results because even if a cloud rains after seeding, it is not known whether the cloud would have rained anyway.

There are three cloud seeding methods: static, dynamic and hygroscopic.

1) Static cloud seeding involves spreading a chemical like silver iodide into clouds. The silver iodide provides a crystal around which moisture can condense. The moisture is already present in the clouds, but silver iodide essentially makes rain clouds more effective at dispensing their water.

2) Dynami ...more

Vapours

To bring artificial rains in the areas

Artificial rain!!! it's just like making someone sneeze by poking something sharp or through snuff box except that here the "someone" are the clouds and the snuff box are some chemicals whose name I forgot like everything else! :-D

Cloud seeding, a form of weather modification, is the attempt to change the amount or type of precipitation that falls from clouds, by dispersing substances into the air that serve as cloud condensation or ice nuclei, which alter the microphysical processes within the cloud. The usual intent is to increase precipitation (rain or snow), but hail and fog suppression are also widely practiced in airports.

It's a process to create artificial rain...!