Why is it in the news?

• A recent cloud seeding experiment in Solapur city, located on the leeward side of the Western Ghats, reported an 18% relative enhancement in rainfall.

Understanding Cloud Seeding

• Cloud seeding is a weather modification technique aimed at inducing artificial rainfall. However, it is effective only when there are adequate pre-existing clouds in the atmosphere.
• The essence of rainfall is the condensation of atmospheric moisture when it exceeds its holding capacity. Cloud seeding expedites this by introducing chemical ‘nuclei’ which serve as focal points for condensation.
• The agents used for seeding can range from iodides of silver or potassium to dry ice (solid carbon dioxide) or liquid propane. These agents can be disseminated either aerially through planes or via ground-based spraying systems.

Prerequisites for Effective Cloud Seeding

• The presence of existing clouds is fundamental; cloud seeding cannot conjure rain from a clear sky.
• Only specific cloud types are amenable to seeding. They need to be sufficiently deep and maintain a temperature between -10 and -12 degrees Celsius.
• The technique is most effective when wind speeds are below a certain threshold, conditions often found in mountainous terrains.

Applications

• Rain Augmentation: In situations of deficient rainfall, cloud seeding emerges as a viable method to augment precipitation.
• Economic Impetus: Rainfall plays a pivotal role in ensuring a bountiful harvest, which in turn bolsters the economy.

Challenges and Concerns

• Environmental Impact: Certain chemicals utilized in cloud seeding can be detrimental to the environment, particularly affecting plants that rely on this modified rainfall.
• Cost Intensive: The process of cloud seeding, especially when involving planes, is financially demanding.