Authorities in India’s capital Delhi carried out a cloud-seeding trial on Tuesday to fight the city’s worsening air pollution. The experiment, meant to trigger rain and wash away toxic smog, did not achieve the desired results.
A scientific effort to make rain
Cloud seeding involves firing small particles, often silver iodide, into clouds to create rainfall. The technique has been used worldwide, though many experts question its long-term impact on pollution. A team from the Indian Institute of Technology (IIT) Kanpur joined forces with the Delhi government to conduct the trial over several neighbourhoods blanketed in thick haze. But the attempt — the first in more than half a century — failed due to a lack of moisture in the air.
Smog levels remain dangerously high
For two weeks, Delhi’s Air Quality Index (AQI) has ranged between 300 and 400. This means pollution levels are nearly 20 times above the safe limit. On Tuesday, a Cessna aircraft released flares filled with silver iodide and sodium chloride into the sky. IIT Kanpur later reported that, although it did not rain, the amount of fine particulate matter dropped slightly. The institute said this proved that even with limited humidity, cloud seeding might help improve air quality to a small extent.
A temporary fix, not a solution
However, IIT Kanpur’s director Manindra Agarwal stressed that this was not a long-term solution for Delhi’s recurring pollution crisis. He explained that rain is a clear sign of success, which did not occur. The moisture in the clouds was too low to form rain. Agarwal said his team would continue testing once weather conditions improve. Delhi’s Environment Minister Manjinder Sirsa confirmed that authorities plan to repeat the trial in the coming weeks when the atmosphere holds more moisture.
A history of failed rain-making attempts
Delhi first tried cloud seeding in 1957 and again in 1972, according to the Indian Institute of Tropical Meteorology. Those efforts aimed to fight drought, not pollution. This latest attempt marks India’s first homegrown use of the technology to tackle smog. The city had considered cloud seeding in 2023, but the plan stalled due to pending court approvals. Scientists at the time warned that the method was expensive and rarely successful.
How cloud seeding works
The process speeds up moisture condensation in clouds to form rain. Salt particles serve as ice-nucleating agents, allowing ice crystals to develop. The moisture in the air then clings to these crystals, creating raindrops. Yet the technique depends heavily on humidity levels and suitable cloud conditions, which Delhi lacked during this trial.
Doubts over effectiveness and environmental impact
Experts say there is not enough data to show how much cloud seeding can reduce air pollution. Environmental researcher Abinash Mohanty warned that artificially altering natural weather patterns comes with limits and unknown side effects.
Mixed global results
Around the world, results from cloud seeding have been inconsistent. China claimed success in creating rain before major events such as the Olympics, using rockets, cannons and drones. In contrast, the United Arab Emirates faced criticism after floods in Dubai raised concerns about the method’s safety.
Delhi’s failed trial highlights both the urgency of tackling its toxic air and the uncertainty of using artificial rain as a remedy. Scientists agree that technology alone cannot solve a problem rooted in emissions, weather patterns and urban growth.
