Cloud Seeding Not a Proven Solution for Air Pollution

On November 26, 2025, the Delhi government, in collaboration with the Indian Institute of Technology, Kanpur (IIT-K), conducted cloud seeding experiments aimed at reducing air pollution in the capital city. However, experts have raised concerns regarding the efficacy of this high-cost initiative, labeling it a distraction from more effective solutions to the ongoing air quality crisis.

The Cloud Seeding Experiment

As New Delhi was enveloped in dense smog and air quality reached hazardous levels, the government turned to cloud seeding, a controversial weather-modification technique designed to induce artificial rain. The IIT-K team deployed aircraft to release flares containing seeding agents into the atmosphere. Unfortunately, the experiment did not yield precipitation due to insufficient moisture in the air.

Manindra Agrawal, Director of IIT-K, acknowledged that the moisture content was below 15%, far less than the 50% needed for effective cloud seeding. Despite the low chances of success, the team proceeded with the experiment to gather data on the relationship between moisture content, seeding material, and local air quality conditions. Agrawal stated, “Even if no rain occurred, we wanted to know whether humidity levels increased and, if so, whether that helped reduce pollution and to what extent.”

Questionable Results

In a statement, IIT-K claimed a reduction of 6-10% in particulate matter as a result of the experiment. However, this claim has been met with skepticism from other experts in the field. Over the years, cloud seeding has been repeatedly proposed as a potential solution to curb pollution in Delhi. This recent experiment marked the first such attempt in over 52 years, following similar discussions by previous governments.

The former Environment Minister, Gopal Rao, had sought permission for cloud seeding last year, and Chief Minister Rekha Gupta hailed the trial as a “historic milestone for the city.” Nevertheless, experts like Shahzad Gani and Krishna Achuta Rao from the Centre for Atmospheric Sciences at IIT-Delhi have dismissed the project as “another gimmick in a series of similar unscientific ideas, like smog towers.”

The Complexity of Delhi’s Pollution

Delhi’s pollution is a multifaceted issue stemming from various sources, including geographical factors, human-driven emissions, and temperature-related constraints. Climate scientist Roxy Mathew Koll from the Indian Institute of Tropical Meteorology (IITM) explains that the city’s location in a low-lying basin, bordered by the Himalayas and Aravallis, exacerbates the pollution problem. He notes, “Winter winds are weak, and pollution gets trapped under temperature inversions.”

Temperature inversion is a phenomenon where warmer air traps cooler air near the Earth’s surface, preventing the dispersion of pollutants. Agrawal identifies several well-known sources contributing to Delhi’s pollution, including:

• Stubble burning
• Biomass burning within the National Capital Region (NCR)
• Increased coal use during the cold season
• Vehicular emissions
• Construction activities

Lack of Evidence for Cloud Seeding

Cloud seeding, a technique first attempted nearly eight decades ago, involves modifying existing clouds with particles to enhance rainfall. The seeding agents used can vary based on the temperature of the cloud base. In the recent Delhi experiment, a mixture of silver iodide, common salt, and rock salt was employed.

Despite extensive research on cloud seeding, there remains a significant lack of conclusive data regarding its effectiveness in addressing air pollution. Thara Prabhakaran, a cloud seeding expert at IITM, states, “There is no documented scientific evidence yet that cloud seeding can reduce pollution.”

Koll emphasizes that while cloud seeding is a serious scientific endeavor, it is not a viable solution for air pollution. “It works only when clouds with enough moisture are already present, and even then, its effect is small and short-lived,” he explains. He adds that any artificial rain produced is often very light, leading to only temporary improvements in air quality.

Challenges in Implementation

Sachin Ghude, an IITM scientist specializing in atmospheric chemistry and urban air quality modeling, points out that to achieve significant improvements in air quality, Delhi would require rain almost every alternate day. “However, since cloud cover is only about 20% throughout the winter period, it’s practically impossible to rely on cloud seeding,” he notes. Furthermore, during severe air quality events, cloud cover is often absent, limiting the types of clouds that can be seeded.

Risks Associated with Cloud Seeding

While the discussion around cloud seeding often focuses on its potential benefits, there has been insufficient attention paid to the associated risks. The compounds used to trigger rain, such as silver iodide, are generally considered safe, but their long-term environmental impacts remain uncertain. The lack of comprehensive studies on the ecological consequences of cloud seeding raises concerns about its implementation as a pollution control strategy.

Conclusion

In conclusion, while cloud seeding has been proposed as a potential method to mitigate air pollution in Delhi, the scientific consensus indicates that it is not a proven solution. The complexity of Delhi’s pollution problem, combined with the temporary nature of any improvements from cloud seeding, suggests that more sustainable and long-term strategies are needed to address the crisis effectively. Experts recommend focusing on reducing human-driven emissions, such as those from vehicles and industrial activities, as a more effective approach to improving air quality in the city.

Note: The information presented in this article is based on the latest available research and expert opinions as of October 2023.