A rainy day is most-cherished by people around the world. While poetry glorifies rain, explaining vividly the prosperity and joy it brings along, natural rain is only a feeble hope hanging from a fragile rope for many in parts of our world.
While most parts of India witness rain in the months between June and September, the very concept of ‘artificial rain’ or cloud seeding is a bolt from the blue.
The idea of cloud seeding first took form after World War II, to increase precipitation efficiency artificially. Subsequently, the method began to be used all over the world to enhance snowfall, improve a cloud’s ability to release rain and thus supply natural water in arid areas.
Clouds are made of tiny droplets of water or ice crystals that are formed when water vapour in the atmosphere condenses and cools around dust or salt particles in the air. Without these droplets in the atmosphere, raindrops or snowflakes cannot form and precipitate. Cloud seeding is a weather modification technique that helps a cloud’s ability to produce rain or snow. The process includes ‘seeding’ existing clouds with silver iodine, which is like natural ice crystals. Tiny ice nuclei are introduced into certain types of subfreezing clouds, which thereby provide a base for snowflakes to form. Thereafter, the newly formed snowflakes grow and fall from the clouds to the Earth.
Cloud seeding is done from ground-based generators of aircraft. The DRI Cloud Seeding Research Programme uses ground-based generators. Besides, it also uses subcontracted seeding aircraft. In the operation, they use silver iodide for the formation of ice crystals. When storm systems move through one of the cloud seeding project areas, a small amount of silver iodide solution is burned from the ground-based generators or released from the aircraft. When this reaches the cloud, the silver iodide acts as an ice forming nuclei to produce snowflakes.
While cloud seeding has come to the rescue of more than 50 countries around the world -- boosting rainfall, preventing drought, and helping agriculture, it can also be threatening to the environment.
Experts believe that if the practice becomes commonplace on a larger scale, it could lead to silver toxicity and various other detrimental environmental consequences. Frequent cloud seeding can also throw off the Earth’s natural balance of moisture and disrupt the natural cycle.
