Chemistry
The most commonly used chemicals in the artificial rainmaking or cloud seeding are

Silver Iodide (Ag I)
All of these
Sodium Chloride (NaCl)
Dry Ice (Frozen CO2)

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Chemistry
The open "Sigrees" or coal stoves often require fanning to sustain burning because of

Lack of oxygen in the surroundings of sigrees
Tendency of carbon dioxide to form a layer along with dust smoke
Interrupted release of moisture from the material
Accumulation of smoke and dust over the sigrees

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