As Delhi’s air quality worsens each winter, scientists and policymakers have revived an idea that once sounded almost futuristic — making it rain artificially. In October 2025, the Delhi government, in collaboration with IIT Kanpur, carried out its first modern cloud seeding experiment in more than five decades, hoping to find a natural way to clear the capital’s toxic haze.
The experiment used specially equipped aircraft to disperse silver iodide particles into pre-existing clouds over the city. If successful, these particles act as nuclei around which water vapor condenses, encouraging rainfall.
A Modern Experiment with Historic Roots
The concept of artificial rain is far from new. Its origins trace back nearly 80 years to a small laboratory in Schenectady, New York, where scientists Vincent Schaefer, Bernard Vonnegut, and Irving Langmuir made a remarkable discovery in 1946.
Schaefer accidentally found that adding crushed dry ice to a freezer cloud chamber triggered immediate snow formation. This led to the world’s first successful outdoor cloud-seeding test in 1947 under Project Cirrus, when an aircraft seeded a natural cloud system and produced measurable precipitation.
Since then, countries like the United States, China, Israel, and the UAE have invested in cloud-seeding programs for drought management, irrigation, and pollution control.
Delhi’s 2025 Cloud Seeding Trial
For Delhi, the initiative is both an environmental experiment and a desperate measure. Under the guidance of IIT Kanpur’s Department of Atmospheric Sciences, a Cessna aircraft released eight flares containing silver iodide and sodium chloride over Burari, Karol Bagh, and Mayur Vihar on October 27, 2025.
The operation was timed to coincide with favorable meteorological conditions — cloud thickness, temperature, and humidity that could allow condensation.
Officials confirmed that this was the third recorded attempt in India and the first for Delhi since 1971–72, when similar experiments in Maharashtra had shown rainfall increases on seeded days.
“This is not about forcing nature but about optimizing conditions that already exist,” explained a scientist from IIT Kanpur. “If the data shows even a small increase in rainfall or particulate washout, it could reshape how India responds to pollution episodes.”
Why Delhi Is Turning to the Skies
The idea gained momentum as Delhi’s Air Quality Index (AQI) crossed severe levels, exceeding 450 µg/m³ PM 2.5 in several areas.
Smog season in the NCR region worsens every year due to:
- Crop-residue burning in neighboring states
- Vehicular emissions
- Industrial pollutants
- Weather conditions that trap pollutants close to the ground
Conventional pollution-control measures — such as construction bans and traffic restrictions — often fall short. Artificial rain offers a temporary but potentially powerful way to wash out airborne pollutants and provide short-term relief.
The Science Behind Cloud Seeding
Cloud seeding relies on introducing aerosol particles like silver iodide or common salt into clouds containing supercooled water vapor.
These particles serve as condensation nuclei, encouraging microdroplets to coalesce into larger drops that fall as rain.
For cloud seeding to work, two main conditions must be met:
- Clouds must already contain enough moisture, typically in the 0 °C to −10 °C temperature range.
- Wind and humidity must allow seeded droplets to grow and fall before evaporating.
While the process cannot create clouds from scratch, it can enhance existing ones to release precipitation earlier or more efficiently.
Global Experience with Artificial Rain
Over 50 countries have experimented with cloud seeding for weather modification or air quality improvement.
- China conducts the world’s largest program, using rockets and aircraft to seed clouds over Beijing and northern provinces.
- United Arab Emirates runs regular missions under its National Center of Meteorology to improve rainfall in arid regions.
- United States states such as Texas and Nevada use cloud seeding to replenish reservoirs during droughts.
Results have been mixed but promising, with rainfall increases of 10–20 percent under favorable conditions.
Challenges and Environmental Concerns
Despite its potential, cloud seeding remains controversial.
- Effectiveness varies: It requires ideal weather conditions and is difficult to measure precisely.
- Environmental caution: Silver iodide, though used in small quantities, is a heavy metal compound and must be managed responsibly.
- Cost and logistics: Each operation involves specialized aircraft, trained meteorologists, and real-time data coordination.
Environmentalists also warn that artificial rain is not a substitute for reducing emissions, but rather a short-term relief tool.
What Happens Next in Delhi
The Delhi government will analyze satellite data, rainfall logs, and particulate readings from monitoring stations to determine if seeding reduced PM 2.5 levels.
If results are positive, officials plan to expand the experiment during peak winter pollution weeks in November and December.
Experts believe that consistent, data-driven trials could eventually integrate cloud seeding into Delhi’s Seasonal Air Quality Management Plan alongside mechanical sweeping and emission controls.
“It’s not magic,” noted an IIT Kanpur researcher. “But it might just be one of the few scientific tools left to buy time while cleaner long-term policies take effect.”
FAQs
What is cloud seeding?
Cloud seeding is a scientific technique used to enhance rainfall by dispersing tiny particles such as silver iodide or sodium chloride into existing clouds. These particles act as nuclei, helping water vapor condense into droplets that can fall as rain. It cannot create clouds from nothing, but it can help trigger precipitation when conditions are favorable.
Why did Delhi conduct a cloud seeding experiment?
Delhi’s cloud seeding project aims to reduce air pollution by creating artificial rain that can wash away dust and particulate matter from the atmosphere. The experiment was carried out in collaboration with IIT Kanpur during a period of severe smog, when the Air Quality Index (AQI) had reached hazardous levels.
Who conducted the cloud seeding operation in Delhi?
The operation was a joint effort between the Delhi government and the Indian Institute of Technology (IIT) Kanpur. A Cessna aircraft was used to release eight silver iodide flares over parts of the city, including Burari, Karol Bagh, and Mayur Vihar.
When was Delhi’s cloud seeding experiment conducted?
The trial was conducted on October 27, 2025, marking Delhi’s first modern cloud seeding attempt in over 50 years. It was timed to coincide with suitable cloud conditions for condensation and rainfall.
Does cloud seeding really work?
Yes, but its success depends on the right weather conditions. Cloud seeding has been shown to increase rainfall by 10 to 20 percent when clouds contain enough moisture. However, it does not guarantee rain every time, as results vary with humidity, temperature, and cloud density.
Is cloud seeding safe for the environment?
Most studies suggest that cloud seeding is safe when performed in controlled quantities. Silver iodide is used in very small amounts that do not pose significant harm to humans or the environment. Still, experts recommend careful monitoring to prevent chemical accumulation over time.
Has India conducted cloud seeding before?
Yes. India has carried out cloud seeding experiments in Maharashtra, Tamil Nadu, Karnataka, and Andhra Pradesh in previous years. The 1971–72 Maharashtra trials showed increased rainfall on seeded days, but large-scale adoption has remained limited.
How does artificial rain help reduce air pollution?
Artificial rain helps by washing away airborne pollutants, such as PM 2.5 and PM 10 particles, from the atmosphere. This “wet scavenging” process temporarily clears the air, improving visibility and lowering pollution levels, especially during winter smog events.
Can cloud seeding permanently solve Delhi’s pollution problem?
No. Cloud seeding can only offer short-term relief by cleaning the air temporarily. Long-term improvement requires controlling emissions from vehicles, industries, crop burning, and construction dust. Scientists see cloud seeding as a supportive measure, not a permanent fix.
What happens next after the Delhi experiment?
Researchers from IIT Kanpur and Delhi Pollution Control Committee (DPCC) are analyzing satellite data and air quality readings to assess the impact. If results are positive, the government may conduct further trials during peak pollution months in winter.