Delhi Turns To Cloud Seeding Again Amid Rising Pollution: What We Know

With AQI levels reaching dangerously close to 400, Delhi is once again caught in worsening pollution ahead of Diwali. To combat the deteriorating air quality, the Delhi Government has once again decided to opt for cloud seeding to artificially induce rainfall over the polluted capital.

The Delhi government has already conducted two rounds of cloud-seeding trials near the Indira Gandhi International Airport in the last 15 days, according to PTI.

More trials are expected to be conducted after the festivities of Diwali and Chhath. According to sources who spoke to PTI, the government is unlikely to make any official announcement or confirmation regarding the proposed operations until after Diwali.

This, however, is not the first time that the Delhi government has experimented with artificially producing rain to bring down pollution levels. Last year, the Rekha Gupta government, in collaboration with IIT Kanpur, conducted trials and attempted cloud seeding but failed.

Here's what you need to know about the second attempt at cloud seeding.

What is Cloud Seeding

Cloud seeding is a weather-modification technique used to enhance a cloud’s ability to produce precipitation, artificially encouraging it to release rain or snow. The process involves dispersing substances such as silver iodide, potassium iodide, sodium chloride or dry ice into suitable clouds, often using aircraft.

Clouds are formed when water vapour in the atmosphere cools and condenses around tiny particles, such as dust or salt, known as condensation or ice nuclei. These particles help water droplets or ice crystals form and grow. In cloud seeding, additional particles are introduced into clouds to accelerate this process. In subfreezing clouds, silver iodide can encourage the formation of ice crystals, which grow and eventually fall as precipitation. In warmer clouds, salt particles can help water droplets merge and grow heavier until they fall as rain.

However, cloud seeding cannot create clouds or generate rainfall from clear skies. It requires existing clouds with sufficient moisture and suitable atmospheric conditions. Its effectiveness also depends on the type of cloud, temperature and other meteorological factors.

Induced rainfall through cloud seeding could help temporarily reduce pollution levels in Delhi by washing suspended particulate matter, including PM2.5 and PM10, out of the atmosphere. This process, known as wet deposition, allows rain droplets to capture pollutants and carry them to the ground, potentially improving air quality. However, the impact would be short-lived, as emissions from vehicles, industries, construction dust and other sources continue to add pollutants to the air. Cloud seeding, therefore, may offer temporary relief but cannot serve as a long-term solution to Delhi's pollution crisis.

Concerns Around Cloud Seeding

The technique comes with an array of concerns and factors that could alter the results.

Experts have flagged that a successful outcome of the experiment is not sustainable for Delhi, as its results in bringing down the pollution levels are only temporary.

Dr Thara Prabhakaran of the Indian Institute of Tropical Meteorology, who specialises in Cloud microphysics, told Outlook that winter weather conditions in Delhi are not optimum for Cloud Seeding with the objective of inducing rainfall.

"Wintertime conditions are not suitable for conducting cloud seeding in the area because we don't have suitable clouds there. Additionally, the middle layer of the clouds is very dry. Even if some intervention happens at the upper level of the cloud, it will evaporate coming to the middle layer where the relative humidity is very less," said Prabhakaran.

Pointing to the Cloud Aerosol Interaction and Precipitation Enhancement Experiment (CAIPEEX IV), a seeding experiment carried out by IIT-M in 2018-2019, Dr Prabhakaran explained that the scientific team constructed guidelines in which successful cloud seeding and artificial rain occur; however, the conditions in Delhi are vastly different from those outlined.

Dr Sachin Dinkar Ghude from IIT also conveyed the same concerns about the experiment in Delhi. He said, "We have always had a position that it will not work during winter pollution time. This is due to the lack of clouds. During peak pollution events, our analysis of the past ten years has shown that 90 per cent of the time of these events, there will hardly be any clouds."

Both scientists have noted that even if the experiment results in rainfall, it is only a temporary fix to the much larger issue of Delhi pollution. Delhi faces pollution not only from automobile and industrial pollution, but also from non-local sources such as stubble burning in Punjab; this amalgamation of contributors to the worsening air quality calls for more research and data to be collected in order to reach a permanent solution.

Cloud Seeding In Practice Elsewhere

Cloud seeding is practised in several countries, including the UAE, China, the United States, Saudi Arabia and Australia, primarily to address water scarcity, enhance rainfall, increase snowpack and support agricultural needs. The UAE has invested heavily in the technique to augment rainfall and replenish water resources, while China has used it extensively in drought-hit regions and to support agriculture. Beyond water management, cloud seeding has also been explored as a means of reducing air pollution. China has reportedly deployed the technique to induce rainfall and clear airborne pollutants, with a 2026 study examining operations in the Yangtze River Delta finding that induced precipitation was associated with short-term reductions in PM2.5 and PM10 concentrations. However, the impact was limited across the wider region, with reductions more pronounced in smaller localised areas. While cloud seeding has shown some success under favourable meteorological conditions, its effectiveness remains variable and difficult to establish, as rainfall can occur naturally in seeded clouds.

What Happened Last Year

Delhi's first major attempt to use cloud seeding to combat winter pollution in October 2025 failed to produce the expected rainfall, largely because of unfavourable atmospheric conditions.

The Delhi government had partnered with IIT Kanpur to conduct cloud-seeding trials, hoping to induce artificial rain that could wash particulate matter out of the air. On October 28, 2025, an aircraft released silver iodide and salt-based flares over areas including Burari, Mayur Vihar and North Karol Bagh in two sorties. However, the trials failed to trigger rainfall over Delhi.

IIT Kanpur Director Manindra Agrawal said the moisture content in the clouds was only around 15 per cent, significantly below the levels generally considered suitable for successful cloud seeding. With insufficient moisture, the particles released into the clouds could not encourage enough water droplets to form and grow into rain. A subsequent trial scheduled for October 29 was also called off because of inadequate moisture.

The experiment also raised questions about its cost-effectiveness. The Delhi Cabinet had approved a budget of ₹3.21 crore for the project, but this was the total sanctioned allocation and not the amount spent on the trials. The government later told Parliament that ₹37.93 lakh had been paid to IIT Kanpur as the first instalment.

Separately, IIT Kanpur Director Manindra Agrawal estimated that the two sorties conducted on October 28 alone cost approximately ₹60 lakh. He also estimated that conducting cloud seeding throughout the winter, assuming suitable clouds appeared once every 10 days, could cost between ₹25 crore and ₹30 crore.

Although IIT Kanpur reported some reductions in PM2.5 and PM10 levels following the trials, experts questioned whether these could be attributed to cloud seeding in the absence of rainfall. The experiment highlighted the limitations of using the technique as a reliable pollution-control measure, particularly during Delhi's dry winter months.

The recent trials were conducted at an altitude of approximately 30,000 metres, significantly higher than the altitude of around 10,000 metres from last year, according to PTI. As of now, little is known about the specifics of how this year's trails will be different from 2025. The government is yet to give an official statement on the renewed Cloud Seeding efforts.