A small, single-propeller aircraft operated by IIT Kanpur crisscrossed the overcast skies above northwest Delhi and parts of the National Capital Region on Tuesday, firing silver iodide flares in two cloud seeding trials that failed to produce rain—even as the capital’s environment minister hailed the exercise as “successful”.
The aircraft fired 16 flares—eight in each trial—containing silver iodide and sodium chloride compounds over Burari and surrounding areas, Mayur Vihar, and Noida in attempts to induce rain in a much-debated plan to tamp down air pollution that tends to accumulate this time of the year.
“Delhi has taken an unprecedented, science-first step by adopting cloud seeding as a tool to control air pollution. 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,” Delhi’s environment minister Manjinder Singh Sirsa said.
The initiative has been another flashpoint in Delhi’s politics.
Aam Aadmi Party (AAP) leader Saurabh Bharadwaj held a press conference questioning the BJP-led government’s decision to conduct trials on a day when the India Meteorological Department had already forecast rain. “Will Lord Indra come down to clarify whether it is artificial rain or natural rain?” he said.
The previous AAP government first floated the plan in winter 2023 but failed to execute it, citing unfavourable meteorological conditions. Last winter, AAP again proposed the programme but claimed it did not receive the Centre’s backing for required flight and environmental permissions.
Sirsa has previously attacked AAP for “only talking about such plans” without action.
An IIT Kanpur report released later on Tuesday stated that “two precipitation events were noted”, identifying these as “trace” amounts of 0.1mm over Noida and 0.2mm over Greater Noida according to the website Windy. To be sure, the official weather stations at these locations made no rain reading, Windy does not report actual precipitation but makes model predictions, and the report itself did not state a specific connection of the “trace rainfall” with the sorties.
The IIT report however, drew a causal connection between the exercise and reductions in pollutants in some parts of the city. “The PM2.5 was 221, 230, and 229 reported from Mayur Vihar, Karol Bagh, and Burari, respectively, before cloud seeding, which got reduced to 207, 206, and 203, respectively, after the first seeding”, it said, adding: “one possible explanation is that the denser moisture content created due to seeding particles has helped in settling down a portion of these particles, which translated to these reductions”.
Ashwary Tiwari, an amateur meteorologist who runs the popular IndiaMetSky on X said the IIT Kanpur report only refers to ‘possible’ rainfall in Noida and Greater Noida. “The report cites Windy, which does not show actual rainfall. It is a forecasting model called the European Centre for Medium-Range Weather Forecasts model, which as the name suggests, gives forecasted rain based on the model simulation,” Tiwari said. He stated that even with seeding done over Noida in the second run, a rain gauge or an automatic weather system (AWS) would be needed to assess actual rainfall – if any.
The IIT Kanpur report contended the “moisture content predicted by IMD and other agencies remained low at 10-15%, which is not an ideal condition for cloud seeding”. “However, this situation is also suitable for judging the effectiveness of the seeding material in low-moisture conditions,” it added.
The Delhi Cabinet approved the cloud seeding project on May 7 with a total outlay of ₹3.21 crore for five trials, making each attempt cost roughly ₹64 lakh. The trials, conducted in collaboration with IIT Kanpur, were originally scheduled for late May and early June but were deferred twice—first until late August and early September due to the onset of the southwest monsoon, and again as monsoon rains continued in the region. Tuesday’s attempts compute to about ₹1.28 crore.
Globally, cloud seeding has largely been seen as an ineffective weather modification technique except for in supercooled, high altitude applications to enhance mountain snowpack. Warm-season rainfall remains deeply contested with no scientific consensus yet of success.
Shahzad Gani, assistant professor at IIT Delhi’s Centre for Atmospheric Sciences, dismissed the trials as “futile attempts”, arguing that cloud seeding “cannot solve Delhi’s air pollution crisis”.
“Even setting aside the uncertainty around its effectiveness, it can only work when rain-bearing clouds already exist—and those conditions are extremely rare during the weeks when pollution is at its worst,” Gani said. “And even if some rain does fall, any improvement in air quality would be brief, because the sources of pollution continue.”
Residents of Burari, where Tuesday evening’s sky remained overcast but dry, echoed the scientist’s scepticism. Rajiv Kumar, 41, who has run a bakery in the area for two years, said his shop required sweeping every half hour due to accumulated dust.
“We had heard that the government was saying it would induce rain in this area during today and tomorrow, but so far we have not seen any rain,” Kumar said. “It has been cloudy since last night, so maybe it rains tomorrow. It is a big need, because it is really dusty here, and many people already suffer from coughing and other lung problems.”
Mitthun Kumar, 21, who runs a snack shop nearby, said: “Some customers were talking about the news a few days ago, but we haven’t seen any rain so far. We need it to rain here because the pollution is so high, and it mixes with the dust, which also gets kicked up whenever a car goes by. Our throats are always burning due to this.”
