Delhi expects its first artificial rain on October 29, but can cloud seeding provide clear skies? , explainer news

Last updated:October 24, 2025, 10:21 IST

Delhi is set to receive its first artificial rain through cloud seeding between October 28 and 30. Here’s how the plan works and whether it can really help reduce pollution

With PM2.5 levels touching in Delhi highest mark since januaryDemands for emergency intervention have started rising again. These also include the ambitious plan of Delhi government. artificial rain An attempt to deal with this through cloud seeding air pollution Through climate modification. After earlier delays due to lack of clouds, the project has now entered its operational preparation phase.

Chief Minister Rekha Gupta said that if weather conditions remain favourable, the first artificial rain may occur in Delhi on October 29.

Sharing the update on Twitter, he wrote, “For the first time in Delhi, preparations for artificial rain through cloud seeding have been completed, marking an important technological milestone in the capital’s fight against air pollution.

Gupta said the IMD has predicted cloudy weather between October 28 and 30. His post read, “If the weather remains favourable, Delhi is likely to receive its first artificial rain on October 29.”

So, what exactly is cloud seeding, how does it work, and can it really reduce pollution levels in Delhi?

Let’s break it down.

What is cloud seeding and how does it work?

Cloud seeding is a weather modification technique intended to increase rainfall. It involves dispersing particles of some substance, usually silver iodide (AgI) or salt, into clouds. These particles act as nuclei around which water vapor condenses and eventually falls as precipitation.

There are two major types of cloud seeding:

• Hygroscopic cloud seeding: Involves dropping salt-based particles (such as potassium chloride or sodium chloride) onto the base of warm clouds. These particles help water droplets merge and grow large enough to fall.
• Glaciogenic cloud seeding: This involves injecting substances such as silver iodide or dry ice into supercooled clouds. These particles aid in the formation of ice crystals, which grow as they melt and fall as precipitation.

Materials are usually deployed by aircraft. In case of Delhi, Cessna-206H aircraft modified for cloud seeding and deployed in Meerut is on standby. Aircraft release seeding material into pre-identified clouds, often with flares mounted on the wings that ignite to disperse the particles at specific altitudes.

The initiative is being led in partnership with IIT Kanpur, which is providing technical expertise and has also previously conducted trials in other Indian states.

Delhi conducts first trial for cloud seeding

On Thursday, Delhi successfully conducted its first test flight for the cloud seeding programme, with flare firing between Khekra and Burari to test the readiness of the aircraft and equipment. Fitment of the aircraft, flare deployment and coordination between participating agencies were tested in the four-hour flight, jointly conducted by the Environment Department of the Delhi government and IIT Kanpur, from Kanpur to Delhi en route to Meerut and back to Aligarh.

Environment Minister Manjinder Singh Sirsa said, “Today’s flight was successful in every technical parameter. We have now completed all the necessary tests including flare testing, fitment checks and coordination protocols.” He said that “All the systems – from aircraft to meteorology and environmental monitoring – are in place. Now, the only thing we are waiting for is the arrival of suitable clouds.”

With all preparation steps complete, the capital is now technically ready for its first full-scale cloud seeding and artificial rain.

Why has the plan been delayed despite increase in pollution?

Simply put: no clouds, no rain.

Cloud seeding cannot produce rain from clear skies; it can only be Increase Precipitation occurs in moisture-filled clouds that are already present. Scientists at IIT Kanpur have clarified that the technique works only when the target clouds have at least 50 per cent moisture and are located between 500 and 6,000 meters above the ground, conditions typically associated with nimbostratus clouds.

But Delhi’s skies remain unusually dry and thin, with not enough clouds to launch the operation.

What is the expected effect of artificial rainfall on pollution?

Even light to moderate rainfall can temporarily reduce air pollution. according to moncontrolThe city’s temperature may drop due to artificial rain air quality index (AQI) anywhere between 50 to 80 points depending on the spread and intensity of rainfall.

For example, if Delhi’s AQI is in the “very poor” category (300-400), a successful rain event could bring it down to the “poor” or “moderate” band. Rain helps wash away suspended particles, especially PM2.5 and PM10, which are major pollutants in Delhi’s air during winter.

However, this effect is temporary. Once emissions from vehicles, construction dust, crop stubble burning and industrial activities continue, AQI levels start rising again within a few days unless supported by intensive systemic interventions.

Has cloud seeding been attempted in India before?

India is not new to cloud seeding. States like Maharashtra, Karnataka, Andhra Pradesh, Gujarat and Tamil Nadu have tried cloud seeding to generate rain during drought, especially for agriculture.

The Indian Institute of Tropical Meteorology carried out one of the earliest experiments in 1972, and more recently, Karnataka and Maharashtra deployed this technology in drought-prone districts. However, scientific evaluation of success has been inconclusive.

The CAIPEEX (Cloud Aerosol Interaction and Precipitation Enhancement Experiment) programme, run by Indian scientists, suggests a 15-20 per cent increase in average rainfall under optimal conditions. But in a dense urban environment like Delhi, especially during dry winters, its replication is untested.

What are the limitations and criticisms?

While cloud seeding offers potential short-term relief, experts have identified several limitations:

1. Meteorological uncertainty: Delhi’s winter skies, due to western disturbances and weak monsoon remnants, rarely produce long-lasting, moisture-rich clouds in October and November.
2. Short-term benefits: Even if seeding is successful, the resulting rains provide only temporary relief. Pollution levels may decrease immediately after rain, but start increasing again within a few days unless the main emission sources such as traffic, construction dust, industry and biomass burning are dealt with simultaneously.
3. Environmental concerns: The process typically involves spreading silver iodide or dry ice into clouds. While global studies have found silver iodide to be safe in regulated amounts, environmentalists argue that repeated or large-scale use should be monitored for potential bioaccumulation in soil or water.
4. Scientific ambiguity: A major challenge is attribution. It is difficult to prove conclusively that the rainfall was caused by seeding rather than natural atmospheric processes. Such experiments require controlled comparisons, such as flying one plane through a cloud and leaving another untouched, and require extensive ground-based equipment, which is often lacking in urban environments like Delhi.

The Central Pollution Control Board (CPCB) and the Commission for Air Quality Management (CAQM) have reportedly advised the Delhi government to consider cloud seeding not as a primary solution, but as an experimental measure. according to times of IndiaThese bodies have warned against over-reliance on seeding and stressed that structural reforms are the only long-term answer to Delhi’s pollution crisis.

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