Cloud seeding viable between July 4-11, IMD in report to Delhi govt

A flight map, drawn up in consultation with IIT Kanpur, has been shared with the Directorate General of Civil Aviation

The Delhi government plans to conduct its first-ever cloud seeding pilot between July 4 and July 11, a period when meteorological conditions are expected to be suitable for artificially inducing rainfall, environment minister Manjinder Singh Sirsa said on Saturday.

Monsoon clouds over New Delhi on Saturday. (AP)

The city government has received a weather report from the India Meteorological Department (IMD) indicating this as a potentially viable window. A flight map, drawn up in consultation with IIT Kanpur, has been shared with the Directorate General of Civil Aviation (DGCA) to obtain final clearance for the experiment.

The proposed flight path, which HT has seen, shows the aircraft will fly over parts of north Delhi—including Rohini, Bawana, Alipur and Burari—as well as adjacent areas in Uttar Pradesh such as Loni and Baghpat, possibly triggering rainfall over these regions.

“We had sought detailed six-hour reports from IMD, and the weather department told us conditions were not feasible for cloud seeding till July 3. It is however possible in the window from July 4 to 11, which is when we want to attempt to carry out the first pilot project on artificial rain in Delhi,” Sirsa told HT.

“We had sought detailed six-hourly reports from IMD, and were told conditions would not be viable until July 3. But there is potential for cloud seeding between July 4 and 11, and that’s the window we’re aiming for,” said Sirsa.

The minister said IMD’s detailed reports and a flight map, approved in coordination with IIT Kanpur has now been shared with DGCA to give the final clearance.

“We’ve also asked DGCA to grant us an alternate window in case weather conditions don’t align during July 4–11. The final decision on flight dates will be made on a daily basis depending on conditions,” Sirsa said.

To be sure, distinguishing seeded rain from natural precipitation will be challenging as Delhi should already be in the monsoon season by then. An IIT Kanpur official said suitable moisture is needed for the exercise -- around 50% moisture in the air and low-lying clouds, admitting while they cannot say for certain whether the rain was natural or through cloud seeding, but a correlation can be drawn. “Through seeding, it rains within an hour of the exercise, so if it starts to rain over the area our flight covers and within an hour, we can draw a correlation between the two,” said the official.

According to experts from IIT Kanpur, Nimbostratus clouds—which occur at altitudes between 500 and 6,000 metres above ground level—are best suited for cloud seeding. These clouds must also contain at least 50% moisture content for the process to work. The moisture enables silver iodide (AgI) and other particles to initiate microphysical changes in the cloud, encouraging the formation of ice crystals or raindrops.

The seeding mixture developed by IIT Kanpur combines silver iodide, rock salt, iodized salt, and a free-flowing agent. The precise mix will vary based on real-time weather parameters, especially humidity and vertical cloud development, Sirsa said.

The pilot is part of a ₹3.21 crore government-approved project involving five cloud seeding trials. The Delhi Cabinet cleared the proposal on May 7, with IIT Kanpur leading scientific implementation. Flights will take off from Hindon Airforce Station in Ghaziabad, for which permission has already been secured from the Union ministry of defence.

Sirsa added that Delhi has secured nearly all necessary permissions except for final DGCA clearance. The agencies involved include the Special Protection Group (SPG), IMD, Central Pollution Control Board (CPCB), Union ministries of defence, environment, and home, along with the governments of Uttar Pradesh and Delhi, the Airport Authority of India (AAI) and the Bureau of Civil Aviation Security (BCAS).

To be sure, this is not the first time artificial rain has been proposed as a measure in the Capital. The previous government led by the Aam Aadmi Party (AAP) had first floated the plan in the winter of 2023, but failed to carry out the experiment citing unfavourable meteorological conditions.

The same plan was floated last winter, however, the government said it did not receive the Centre’s backing for the plan, including the flight and environmental permissions required. Reacting to previous such attempts, Sirsa said AAP lacked the will to do such an exercise.

“They were all talk, but no show. This time, we ensured that everything was done properly. We signed an MoU, disbursed funds to IIT Kanpur, got our Cabinet to approve the plan, and pursued all necessary clearances,” Sirsa said. “The AAP spent two years talking but didn’t even release funds or formally approach the required agencies.”

The project has reignited political sparring between the AAP and BJP. On Friday, AAP leader Saurabh Bharadwaj accused the BJP of implementing a long-delayed AAP proposal. “They’re copying Arvind Kejriwal’s vision. The Centre never gave us permissions, but now they’ve cleared everything because BJP is in power,” he said.