First cloud seeding trial held in Delhi; full run on Oct 29: CM

Delhi CM Rekha Gupta called the exercise ‘historic‘ and a major step in Delhi’s fight against pollution

Delhi on Thursday held its first “successful” test of its ambitious cloud-seeding project after a plane released flares laced with rain-inducing chemicals above the city, Delhi chief minister Rekha Gupta said, adding that the government will now carry out the exercise for the first time in the city on October 29.

A layer of smog seen near Yamuna in Delhi on Thursday. (RAJ K RAJ /HT PHOTO)

The trial, however, did not yield rain because of low humidity on Thursday, scientists said.

Delhi chief minister Rekha Gupta announced that the government would attempt full-fledged artificial rain on October 29, calling the exercise “historic” and a major step in Delhi’s fight against pollution. “If conditions remain favorable, Delhi will experience its first artificial rain on October 29,” Gupta wrote on X, citing the India Meteorological Department’s (IMD) forecast of suitable cloud formations later this month.

A specially equipped aircraft, operated by the Indian Institute of Technology (IIT) Kanpur, flew from Kanpur via Meerut, Khekra, Burari, Sadakpur, and Bhojpur, looping back after releasing flares laced with silver iodide and sodium chloride compounds over Delhi’s northern fringe.

To be sure, officials said the flight was “not meant to induce rainfall”, but to check the readiness of the plane, the ignition and dispersal systems, and the coordination among multiple agencies.

According to IIT Kanpur’s report on the test, which HT has seen, “The flight was the proving mission for assessing the capability and endurance of the aircraft, the cloud-seeding fitments, and the coordination between agencies.” The report confirmed that “no precipitation was recorded as the moisture content was below 15%,” noting that successful seeding requires at least 50% relative humidity.

It added that specially designed flares were used to release both silver iodide and sodium chloride compounds. “These are ignited and dispersed into the atmosphere through aircraft-mounted systems to stimulate condensation and cloud formation when sufficient moisture is present,” it said.

Delhi environment minister Manjinder Singh Sirsa described the flight as a “proving run” and an example of “science-based solutions” to tackle pollution. “This initiative reflects Delhi’s resolve to embrace innovation and science-based solutions under the vision of Prime Minister Narendra Modi and the leadership of chief minister Rekha Gupta,” he said.

IIT Kanpur said “two small patches of clouds were observed” during the test. “The pilots reported clear skies around the New Delhi area, and two very small patches of clouds were observed. They seeded the clouds with individual flares,” the assessment by IIT Kanpur added. The flares used Thursday were specially designed pyrotechnic cartridges ignited mid-air and dispersed through nozzles fitted to the aircraft’s wings, it said.

Manindra Agrawal, IIT Kanpur’s director, said that despite the absence of rain, the trial met its objectives. “We needed to verify that all systems work and that the chemicals disperse properly. While there was insufficient moisture for rainfall, the aircraft and seeding systems performed as expected,” he told HT.

Cloud seeding involves dispersing tiny particles such as silver iodide into clouds to trigger condensation. While the technique has been used in other regions, its effectiveness in controlling pollution remains debated.

The government had approved the ₹3.21 crore project in May, planning five cloud-seeding trials with technical support from IIT Kanpur. However, the effort faced repeated delays through the monsoon months due to poor meteorological conditions and flight restrictions.

On the same day, the Delhi government deployed over 2,000 enforcement teams on-ground to tackle pollution sources. Further, 376 anti-smog guns, and 266 water sprinklers were also deployed.