Explained: What Is Artificial Rain And Will It Help Delhi Combat Pollution

The Delhi government is considering implementing artificial rain through cloud seeding this month to combat the rising air pollution levels in the city. On Wednesday, Delhi Environment Minister Gopal Rai met with a team from IIT Kanpur to explore the feasibility of this approach. Mr Rai mentioned that if the sky is cloudy on November 20 and 21, Delhi might witness artificial rainfall.

What is artificial rain?

Artificial rain, also called cloud seeding, involves introducing chemicals like silver iodide, potassium iodide and dry ice into the atmosphere via aircraft or helicopters. These particles attract water vapour, leading to cloud formation and subsequent rainfall. The methods include seeding supercooled clouds with silver iodide or dry ice and using hygroscopic materials like salt particles for warm clouds.

IIT Kanpur's innovative approach

IIT Kanpur is spearheading the groundbreaking initiative to induce artificial rain as a temporary solution to combat pollutants and dust in Delhi. The institute, which has been researching pollution control since 2018, successfully conducted cloud seeding trials in June this year. With the approval of the the aviation watchdog Directorate General of Civil Aviation (DGCA), IIT Kanpur plans to deploy aircraft equipped with cloud-seeding devices to create rains that wash away pollutants.

The team plans to employ a six-seater Cessna plane to release salt from flares into the clouds. This process aims to stimulate and speed up the condensation process, ultimately resulting in rainfall.

Countries all over the world have been reportedly working on cloud seeding since as early as the 1940s. For many years, China and countries in the Middle East have used artificial rain to address air pollution. The water particles start accumulating around a chemical called silver iodide and droplets are formed. Once these drops are heavy, the water drops start falling on the earth, causing rain. China, in particular, has used artificial rain several times to combat pollution.

Estimated cost

The IIT team informed the Delhi government that the estimated cost for the project is around Rs 1 lakh per square kilometre. "In a significant development, the Delhi government has decided to bear the cost of artificial rain that could be made to happen by November 20 if the Centre extends its support to the Delhi government," said a senior government functionary.

"The chief secretary has been directed to inform the Supreme court that the Delhi government has in principle agreed, based on the advice of an IIT-Kanpur team, to bear the cost of Phase 1 and Phase 2 pilots (totalling Rs 13 Crore) for carrying out artificial rain," the person said.

Will artificial rain really help?

Manindra Agrawal, the IIT Kanpur professor leading the project, says artificial rain could give people in the National Capital Region (NCR) a brief break from bad air quality for about a week. 

Delhi woke this morning to overnight rains, which was not artificial, that improved (slightly and temporarily) the air quality crisis; the AQI dropped from nearly 500 last night to 407 at 7 am. This, as the Supreme Court, was quick to point out, had nothing to do with any effort of the Delhi or central government.

Challenges and considerations

While artificial rain offers temporary relief, it is not a long-term solution. Cloud seeding requires permission from various authorities, including the Ministry of Home Affairs and the Special Protection Group. It also has environmental drawbacks, such as acidification of oceans, ozone layer depletion and potential harm from the toxic silver iodide.

The government is planning additional steps, including temporarily closing schools for in-person classes, and enforcing Stage IV of the Graded Response Action Plan (GRAP), to address rising pollution levels in Delhi.