Delhi Gets First Ever Cloud Seeding Trial To Fight Air Pollution

New Delhi: On October 28, Delhi witnessed its first ever cloud seeding trial. A cloud seeding aircraft took off from Kanpur for the trial, according to a report by PTI. The trial was conducted over certain parts of Delhi, including Burari and Karol Bagh.

Delhi environment minister Manjinder Singh Sirsa said that the trail lasted for 30 minutes and that eight fire flares were released during the process. He told PTI that rains could occur within 15 minutes to 4 hours after the cloud-seeding trial.

A second cloud-seeding trial will be conducted later in the day in Outer Delhi, the report quoted Sirsa as saying. At least nine such trials have been planned over the next few days, per the minister.

“If these trials prove successful, a long-term plan will be implemented through February,” Reuters quoted Sirsa as saying.

Artificial rain triggered by cloud seeding can bring down pollution by as much as 50%, but may need to be repeated, Manindra Agrawal, a scientist at IIT-Kanpur told Reuters. 

“If it rains, pollution comes down, (but) it will rise again because the source ... has not gone. Therefore, whenever the cloud cover is there, one has to repeat the process,” Reuters quoted him as saying.

Earlier on October 28, Sirsa had told the press that Delhi was preparing for cloud seeding on the day, and that it would take place if the cloud seeding aircraft at Kanpur succeeded in lifting off. There were some low visibility concerns, per a report by the ANI that quoted him.

What is cloud seeding?

Cloud seeding is a process by which clouds are ‘seeded’ — by introducing a cocktail of common chemicals — to trigger rainfall artificially.

Aircrafts are used to release explosive flares containing these chemicals (such as silver iodide, dry ice or salts) into existing clouds. This induces existing water droplets in the cloud to attract more moisture, become heavier, and fall down as rain. 

Cloud seeding has been used to induce rain over water-stricken areas, primarily to aid agriculture. A recent study by Indian scientists found that while cloud seeding agents do boost crop yield, excessive rainfall can pose significant risks to the yield. More than 50 countries have used cloud seeding since the 1970s to suppress hail, because cloud seeding also reduces the size of hail particles. 

Cloud seeding has also been identified as a temporary solution to address bad air quality. This works because rainfall is known to bring down levels of particulate matter — a major air pollutant — in the atmosphere.

However, according to Shamim Haque Mondal who is with the Physics Division, State Forensic Science Laboratory, Kolkata, “artificial rain doesn’t help in the long run unless the cause of the problem is entirely removed”, per his article in Down To Earth.

While cloud seeding comes with some benefits, the process also releases toxic chemicals such as silver iodide into the atmosphere. Constant exposure to these chemicals could be dangerous for human health and the environment, some studies show.

For instance, a study in 2016 found that the silver iodide from cloud seeding may actually affect life forms living in both land and water — if the experiment is repeatedly applied in a specific area and large amounts of such seeding materials accumulate in the environment.

First time in air pollution fight

While cloud seeding has been used in some parts of the country to trigger rains in water-stressed areas such as in Marathwada, Maharashtra, this is possibly the first time that a cloud seeding experiment is being conducted to fight air pollution in India.

Delhi has been witnessing very poor air quality since Diwali on October 20; currently Stage II of the Graded Response Action Plan to limit activities that add to the air pollution is in place across the national capital. 

According to an ANI report, the AQI in Delhi was 306 as of 8 am on October 28. This is categorised in the ‘very poor’ category. The next stage, above 400, is ‘severe’. It is the final stage on the scale.

As of 8 am on the same day, the AQI in Anand Vihar was 321, RK Puram stood at 320, Siri Fort at 350, Bawana at 336, Burari Crossing at 326, Dwarka Sector 8 at 316, Mundka at 324, Narela at 303 and Punjabi Bagh at 323, per the report.

Previous test run unsuccessful

An earlier test run, the PTI report said, was apparently unsuccessful. Per the report, the government had conducted a test flight over Burari last week, releasing small quantities of silver iodide and sodium chloride compounds to trigger artificial rain.

However, due to low atmospheric moisture of less than 20%, as against the 50% typically required for cloud seeding, rainfall could not be induced, the report said.

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