Delhi conducts 2 cloud seeding trials

Delhi completed two cloud seeding operations in several parts of the city on Tuesday. Environment Minister Manjinder Singh Sirsa said there were reduction in PM2.5 and PM10 levels in multiple locations.

The official government report said two precipitation events were recorded - one in Noida at 4 pm (0.1 mm of rain) and another in Greater Noida at 4 pm (0.2 mm).

A Cessna aircraft operated by the IIT-Kanpur took off from the institute’s airfield, entered Delhi airspace via Meerut, and seeded clouds along a 25-nautical-mile corridor covering Khekra, Burari, North Karol Bagh, Mayur Vihar, Sadakpur, Bhojpur and surrounding areas.

“Delhi has taken an unprecedented, science-first step by adopting cloud seeding as a tool to control air pollution,” Sirsa said.

“Our focus is to assess how much rainfall can be triggered under Delhi’s real-life humidity conditions. With every trial, science guides our actions—for the winter and all year round,” he said.

Each sortie released eight 0.5-kg chemical flares, burning 2–2.5 minutes apiece, containing hygroscopic salts. Clouds held 15-20 per cent humidity.

The first flight, at 4,000 feet, deployed six flares over 18.5 minutes; the second, launched at 3:55 pm, released eight flares between 5,000 and 6,000 feet. Operations lasted 90 minutes per sortie.

At Mayur Vihar, Karol Bagh and Burari, PM2.5 levels fell from 221, 230 and 229 µg/m³, respectively, to 207, 206, and 203 µg/m³. PM10 dropped from 207, 206, and 209 µg/m³ to 177, 163, and 177 µg/m³, government report said.

“With minimal winds, this reduction is attributed mainly to the added cloud moisture and particle settling caused by the cloud seeding particles,” Minister Sirsa said.

Radar indicated possible showers in the next 24 hours, officials said. “Each data point from our air quality tracking brings us closer to building a clean, green Capital,” Sirsa said.

He said scientists were analysing readings from 20 monitoring sites and a report would be released on Wednesday. The trials are part of a five-flight Rs 3.21-crore MoU signed with the IIT-Kanpur in September, scheduled between October 1 and November 30 over north-west Delhi.

“Depending on the results, we are prepared for further cloud seeding sorties in the coming weeks and, after the first round, the results will determine whether we should plan more seeding experiments till February,” Sirsa said.

Environmental experts, however, have questioned the long-term impact of such experiments. “Addressing air quality requires tackling sector-specific emissions from transport, power and construction. Without that, no real impact can be achieved. Cosmetic measures like smog towers, anti-smog guns or cloud seeding may create short-term visibility benefits but are not sustainable solutions,” said Sunil Dahiya, lead analyst and founder of Envirocatalysts, a Delhi-based environmental think-tank.

The last cloud-seeding attempt over Delhi occurred in the 1970s by the Indian Meteorological Department.