NEW DELHI: Delhi on Tuesday carried out its first-ever cloud seeding trial in a bid to trigger artificial rain and bring temporary relief from the city’s toxic post-Diwali smog. The experiment, conducted by a team of scientists and officials using aircraft over parts of the capital, is being closely watched as authorities explore whether artificial rain can help clean Delhi’s air, even if for a short while.
Cloud seeding is a weather modification technique that aims to induce rainfall from existing clouds by dispersing certain substances into the atmosphere. Typically, chemicals such as silver iodide, potassium iodide or salt particles are released through aircraft or rockets into moisture-laden clouds.
These particles act as nuclei around which water vapour condenses, forming droplets that can grow heavy enough to fall as rain.
The key requirement, however, is the presence of clouds with sufficient moisture. Seeding cannot create rain from clear skies. In Delhi’s trial, aircraft released a combination of salts and silver iodide into pre-identified cloud formations over the city.
Scientists expect that, if the atmospheric conditions are favourable, these particles will stimulate rainfall, which can help wash down suspended pollutants such as PM2.5 and PM10 from the air. Similar methods have been used in countries like China, the United Arab Emirates and the United States for purposes ranging from drought management to pollution control, though with mixed results.
While cloud seeding can modestly increase rainfall by about 10 to 20 per cent, it is highly dependent on weather conditions. Delhi’s pollution peaks during late autumn and winter, when humidity is low and clouds are often shallow, making the method less reliable.
Moreover, even if the experiment succeeds, any improvement in air quality would be temporary. Once the rain stops, pollutants from vehicles, industries, construction and crop burning continue to accumulate, bringing pollution levels back up.
Scientists also warn that cloud seeding is not a sustainable solution to the capital’s air crisis. While it can provide short-term relief, it does not address the root causes of pollution. “It’s not yet clear whether this will have any real impact on Delhi’s air quality during the winter months,” said Anumita Roychowdhury, executive director, research and advocacy at the Centre for Science and Environment.
“At that time of year, the weather conditions are such that pollutants get trapped close to the ground, making it extremely difficult for them to disperse. Even if cloud seeding manages to trigger some rain, the effect will be very short-lived. It’s a temporary, and very expensive, measure.”
Ultimately, Delhi’s cloud seeding trial marks an important scientific effort, but one that should be viewed with tempered expectations. Artificial rain, if successful, may clear the air for a few hours or days, offering symbolic respite rather than lasting change.
The city’s real challenge lies in cutting emissions, regulating dust, and curbing stubble burning, not in waiting for rain, artificial or otherwise.
Hacking the Capital’s sky
How it works: aircraft released silver iodide and salt particles into moisture-laden clouds to trigger rainfall by encouraging condensation around these particles
Goal: to wash down suspended pollutants such as PM2.5 and PM10, providing temporary relief from hazardous air quality
Conditions required: cloud seeding needs existing clouds with sufficient humidity; it cannot generate rain from clear skies, making timing crucial
Technology used: modified aircraft equipped with flare systems and dispersal devices released the seeding agents at pre-identified altitudes over Delhi
Expected impact: experts estimate seeding can increase rainfall by 10–20% if weather conditions are favourable
Limitations: effectiveness depends heavily on cloud type, moisture content, and wind patterns; Delhi’s dry winter conditions often make success uncertain
Expert opinion: scientists caution that even if the trial succeeds, the improvement in air quality will be short-lived unless emission sources are curbed
Global precedent: cloud seeding has been used in China, the UAE and the U.S. for drought management and pollution control, with mixed results
