Delhi prepares for its first artificial rain: What is cloud seeding, and how does it happen - The Times of India

Diwali just got over, and Delhi is once again grappling with severe air pollution, with PM2.5 levels hitting their highest since January. This spike has demanded immediate action to reduce the hazardous air quality choking the city. Among various proposed measures, the Delhi government is set to try cloud seeding to induce artificial rain.Although cloud seeding has been experimented with in other parts of India and the world for decades, using it in a metropolis like Delhi, especially in late October, has its own set of challenges. Lately, the city's skies have not cooperated with ideal cloud conditions, leading to delays in initiating the project.However, Delhi CM Rekha Gupta said that Delhi might witness its first artificially induced rain by Oct 29, 2025Cloud seeding is a weather modification technique that is used to increase rainfall by introducing specific particles into clouds. The process usually involves dispersing substances such as silver iodide or salt-based particles into moisture-rich clouds, which leads water vapour to condense around these particles, and then results in rain.Delhi's project uses a modified Cessna-206H aircraft to release these seeding agents into target clouds, with flares that ignite at specific altitudes. The technical support and research come from IIT Kanpur, partnering with Delhi's environment department.Delhi recently completed its first test flight for the cloud seeding project. During this flight, they checked how well the aircraft was modified, tested the flare deployment, and made sure all the teams involved were working smoothly together. The flight covered a route from Kanpur to Delhi, passing through Meerut.Chief Minister Rekha Gupta also shared on X that, "For the first time in Delhi, preparations have been completed to induce artificial rain through cloud seeding, marking a significant technological milestone in the capital's fight against air pollution." She said, "If the weather remains favourable, Delhi is likely to witness its first artificial rain on October 29," citing forecasts from the Indian Meteorological Department (IMD).Cloud seeding requires clouds with sufficient moisture to work without them, no amount of seeding will produce rain. According to scientists from IIT Kanpur, seeding is effective only if clouds hold at least 50% moisture and lie between 500 and 6,000 meters above ground. Delhi's recent dry and thin skies have lacked the necessary cloud mass, causing delays.Rainfall, including artificially induced rain, can wash pollutants like PM2.5 and PM10 out of the air, temporarily improving the Air Quality Index (AQI). For instance, if the AQI is in the "very poor" range (300-400), rain might bring it down to "poor" or "moderate" levels.Cloud seeding isn't new to India, states like Maharashtra, Karnataka, Andhra Pradesh, Gujarat, and Tamil Nadu have all tried it to mitigate drought and boost rainfall, especially for agriculture. The Indian Institute of Tropical Meteorology pioneered experiments in 1972, but results have remained mixed and inconclusive.The CAIPEEX (Cloud Aerosol Interaction and Precipitation Enhancement Experiment) program found, on average, 15-20% rainfall enhancement under optimal conditions.Meteorological Limitations: Delhi's winter skies rarely have the long-lasting, moisture-heavy clouds needed for sustained rainfall.Temporary Benefits: Even successful seeding results only in brief pollution reduction.Uncertainty: It is difficult to attribute rainfall directly to seeding versus natural weather patterns without proper controlled studies, often impractical in cities.Central Pollution Control Board (CPCB) and the Commission for Air Quality Management (CAQM) advise viewing cloud seeding as an experimental tool rather than a primary pollution solution.