The cloud seeding method is a part of the Weather Modification process and it helps in increasing the amount of precipitation by artificial means. Some of the chemical substances such as aluminium oxide, barium, or silver iodide are spread onto the clouds with the help of aircrafts. These chemical substances exist in the powder form and reacts chemically with clouds to form rain or snow, as these two are common forms of precipitation. The method of cloud seeding works only when the water vapor already exists in the air.