Delhi govt readies post-Diwali artificial rain plan to fight pollution: How it will work

Four successful trial flights of artificial rain have already been conducted by the Delhi government and the project now awaits IMD’s green signal.

Delhi government is “fully prepared” to carry out cloud seeding in the Capital to induce artificial rain in a bid to reduce air pollution around Diwali, environment minister Manjinder Singh Sirsa said on Wednesday. Four days of trial flights have already been conducted over the target area in northwest Delhi, and the project is now awaiting a final go-ahead from the India Meteorological Department (IMD).

Students in Noida go to school amid a smoggy morning, AQI in Delhi-NCR has dropped to 'poor' ahead of Diwali. (Sunil Ghosh/HT)

“Our aircraft is ready at Meerut. The pilots have familiarised themselves with the flight path. We’re only waiting for IMD’s green signal and the right cloud conditions. If all goes well, the first trial could happen even on the day-after Diwali or the following day, if conditions are suitable,” Sirsa said.

Govt on plan to combat post-Diwali pollution

• 4 days of trial flights were successfully conducted over northwest Delhi - the chosen zone for the pilot project.
• Aircraft is stationed at Meerut, and pilots have completed familiarisation with the flight path.
• The project is awaiting IMD’s green signal and the right cloud conditions for the actual seeding.
• If approved, the first trial could take place the day after Diwali or the following day, depending on weather.

How the plan works

• Cloud seeding involves dispersing substances such as silver iodide (AgI) into clouds to enhance their ability to produce rain.
• The Delhi project is being carried out in collaboration with IIT Kanpur, which has modified a Cessna-206H aircraft for the purpose.
• Nimbostratus clouds - typically between 500m and 6,000m above ground - are ideal for seeding, but must contain at least 50% moisture.
• Currently, Delhi’s skies lack sufficient moisture or cloud density, which is delaying the operation.
• “We are closely monitoring atmospheric conditions, waiting for the right window,” said an IIT official involved in the project.

Expected impact on pollution

• Rain can improve air quality by 50–80 AQI points, depending on intensity and spread.
• According to experts, if AQI is “very poor”, it may improve to “poor”; if “poor”, it may improve to “moderate”.
• Light rain or drizzle is unlikely to make a significant difference. Sustained and strong showers are needed for a “washout effect.”
• “Wind speed, area of influence and rain intensity will determine the impact,” said Dipankar Saha, former head of CPCB’s air lab.

The Delhi Cabinet approved the ₹3.21-crore plan in May. Permissions from over 10 bodies - including the Union environment, defence and home ministries, DGCA, BCAS, AAI and the UP government - have been secured. A MoU with IIT Kanpur was signed on September 25, with DGCA granting flight clearance a day earlier.

Originally slated for May-June, the trials were postponed due to the monsoon. A revised window in August-September was missed as the monsoon lingered until September 24. Another planned window in early October was delayed due to unexpected rainfall from a western disturbance.

While officials are optimistic, experts remain cautious. “We have seen such experiments in Dubai to tackle droughts, not pollution. In Pakistan, something similar was tried but AQI rebounded almost instantly,” said Sunil Dahiya, founder of Envirocatalysts. “For Delhi, the entire city would need to be seeded. So far, we don’t even know if it will lead to rain, let alone enough rain to bring down AQI.”