Why Delhi’s cloud seeding attempt failed and where it has worked elsewhere

New Delhi: Delhi’s much-anticipated cloud seeding experiment aimed at inducing artificial rain to fight rising air pollution failed to yield results on Tuesday, largely due to unfavourable weather conditions. The trial, jointly conducted by the Delhi government and the Indian Institute of Technology (IIT) Kanpur, was carried out over areas including Burari, Karol Bagh, Mayur Vihar, and Badli.

According to the India Meteorological Department (IMD), no rainfall was recorded in the city following the operation. However, scientists remain optimistic, calling it an important step in understanding how the technology can be adapted for local conditions.

In a statement, IIT Kanpur said another cloud seeding trial planned for Wednesday has been put on hold because of insufficient moisture in the clouds, adding that the next attempt will be made when conditions become favourable.

Low moisture led to failure

Explaining the reason behind the failure, IIT Kanpur Director Manindra Agrawal said that the clouds over Delhi simply did not have enough moisture to generate rain.

“We did not get a lot of cloud moisture. It was only around 15%. Given the low moisture content, the possibility of rain is very small. So we did not achieve success from that perspective. But still, we got a lot of very useful information.”

The operation used a Cessna aircraft that released flares filled with silver iodide and salt compounds from Meerut into Delhi’s skies. These flares, designed to burn for about two minutes each, act as nuclei to encourage water droplets to form. While the city saw no measurable rain, drizzles of 0.1 mm in Noida and 0.2 mm in Greater Noida were recorded.

Despite the lack of rainfall, Delhi’s Environment Department reported a minor drop in PM 2.5 levels in some areas where the trial was carried out. Environment Minister Manjinder Singh Sirsa described the attempt as a “major scientific step” and said more trials, up to ten in total by February, are being planned, depending on favourable weather conditions.

Global success stories offer hope

While Delhi’s effort fell short, cloud seeding has shown varying levels of success worldwide.

The United Arab Emirates (UAE) is among the most successful examples. Through continuous research and advanced seeding technology, the UAE has reported 10–30 per cent increases in rainfall, particularly in arid regions. Similarly, China operates one of the world’s largest weather modification programs, claiming rainfall boosts of up to 15 per cent in targeted areas.

In the United States, cloud seeding is primarily used to enhance snowfall in mountain regions, contributing to water supplies.

Other countries have had mixed experiences. Israel, which began experimenting with cloud seeding in the 1960s, discontinued its program in 2021 after studies found negligible impact on long-term rainfall. South Africa and Australia have also reported limited success, showing that outcomes depend heavily on atmospheric conditions and timing.