No rain in Delhi, IIT Kanpur Director explains why

After a gap of 53 years, Delhi on Tuesday carried out cloud seeding experiments to induce artificial rain and curb the city’s worsening air pollution. However, the initial attempts yielded limited results due to low moisture levels in the clouds, according to officials from IIT Kanpur, which is leading the project in collaboration with the Delhi government.

Speaking to TV channels, IIT Kanpur Director Prof Manindra Agarwal said the trial was “not completely successful” but provided valuable insights for future operations.

“Unfortunately, the clouds today had very low moisture content — around 15 to 20 per cent — which makes it difficult to trigger rainfall. Still, this exercise has boosted our confidence to continue with further trials,” he said.

The team used a mixture containing 20 per cent silver iodide and the rest comprising rock salt and common salt. Around 14 flares were fired from a Cessna aircraft over several parts of Delhi, including Burari, Karol Bagh, Mayur Vihar and Badli.

While the India Meteorological Department (IMD) did not record any rainfall in Delhi, light precipitation was reported in nearby Noida (0.1 mm) and Greater Noida (0.2 mm).

According to a report from the Delhi government, the trials did result in a slight reduction in pollution levels in the areas targeted. The PM 2.5 concentration dropped from 221–230 to around 206–207, while PM 10 levels fell from around 207–209 to 163–177 after the exercise.

Environment Minister Manjinder Singh Sirsa described the operation as an “emergency scientific measure” to provide temporary relief from toxic air. “The humidity was only 15 to 20 per cent, so heavy rainfall was not expected. Still, even light precipitation can help bring down pollution levels,” he said. Two more flights are scheduled for Wednesday, with more trials planned depending on cloud cover.

Agarwal said that cloud seeding should not be viewed as a permanent fix. “This is an SOS solution — useful during extreme pollution episodes. But the real solution lies in controlling pollution at its source,” he said, adding that costs could be reduced in future if the flights are launched from within Delhi.

Environmentalists, however, remained skeptical. Climate activist Vimlendu Jha called the move a “temporary, end-of-the-pipe solution” that may provide brief relief but fails to tackle the root causes of Delhi’s pollution crisis. He also raised concerns about the environmental impact of chemicals such as silver iodide.

This marks Delhi’s third major cloud seeding attempt — the first was in 1957 and the second in the early 1970s, according to climate scientist Roxy Mathew Koll of the Indian Institute of Tropical Meteorology.

As the city’s air quality index (AQI) hovered at 294 (‘poor’ category) — a slight improvement from 301 (‘very poor’) the previous day — officials said more such experiments could be conducted through February if weather conditions permit.