How artificial rain made and rained?
Even though air may be supersaturated with water vapour (that is it contains more water vapour than it would in equilibrium) it often takes something to start condensation. Various chemicals, both organic and inorganic, can serve as nucleation centres – points around which droplets will form. The actual details of how microdroplets form and grow to raindrops is still not fully understood and a good deal of work is going on in this area, in part because of its importance in modeling climate. Silver iodide was one of the first chemicals to be used to make rain. This is dispersed, either from a ‘plane or via a rocket sent into water-bearing clouds, as finely divided particles.
