The Delhi Government on Tuesday afternoon conducted two cloud seeding trials to stimulate rainfall in the national Capital.
Though the process was marred by low moisture content in the clouds, the Government in its official report, has claimed that the cloud seeding trials helped in the reduction of particulate matter at locations where the exercise was carried out even as conditions were not ideal for it.
The report said that two precipitation events were recorded — Noida at 4 pm (0.1 mm of rain) and Greater Noida at 4 pm (0.2 mm). The official Government report said data from 20 locations were collected for AQI monitoring, especially particulate matter PM2.5 and PM10, which will be directly impacted by cloud seeding.
Cloud seeding involves producing artificial rainfall by releasing particles into moisture-rich clouds.
According to a report, before the first seeding, PM2.5 at Mayur Vihar, Karol Bagh, and Burari was 221, 230, and 229 µg/m³, which fell to 207, 206, and 203 µg/m³, respectively after the operation.
PM10 at the same sites dropped from 207, 206 and 209 µg/m³ to 177, 163 and 177 µg/m³ post-seeding.
With minimal winds reported, this reduction is attributed mainly to the added cloud moisture and particle settling caused by the cloud seeding particles.
The moisture content predicted by the India Meteorological Department (IMD) and other agencies remained low at 10-15 per cent, which is not an ideal condition for cloud seeding.
However, this situation is also suitable for judging the effectiveness of the seeding material in low-moisture conditions, the report said.
The report noted that winds were negligible at that time but the denser moisture content created due to seeding particles has helped in settling down a portion of these particles, which translated to these reductions.
Both sorties, managed by IIT Kanpur’s expert team, launched from IIT Kanpur and Meerut airfields and covered Khekra, Burari, North Karol Bagh, Mayur Vihar, Sadakpur, Bhojpur, and surrounding sectors.
Each flare weighed about 2 to 2.5 kg, with eight flares released per sortie, dispersing a tested mixture designed to enhance precipitation potential. Reported humidity levels in seeded clouds ranged from 15 per cent – 20 per cent—lower than ideal, but sufficient for a scientifically meaningful test.
The starting point was the IIT Kanpur airstrip from where the flight took off at 12.13 pm and the seeding points covered were Khekra, Burari, North Karol Bagh, Mayur Vihar, Sadakpur and Bhojpur. The second seeding sortie was conducted from Meerut airstrip itself, carrying four kilograms of seeding material and landing back at Meerut airstrip.
The seeding started at 3.45 pm, with the first seeding point at Khekra at 4.08 pm, followed by Burari, around Mayur Vihar, Pavi Sadakpur, Noida, Bhojpur, Modinagar and Meerut, landing back at 4.45 pm, the report said.
The operation lasted about one and a half hours for each sortie, ensuring consistent coverage. Delhi Environment Minister Manjinder Singh Sirsa emphasized, “According to expert forecasts, rain after seeding could occur anytime in the next 24 hours, depending on cloud moisture.
Initial weather radar readings and on-ground observations recorded light rainfall of 0.1 to 0.2 mm at Delhi-Noida Border around 4 PM, indicating some positive response from the seeded clouds.”
Sirsa further explained, “Each data point from our air quality tracking brings us closer to building a clean, green Capital. Scientists will now closely study all pre- and post-seeding data from all 20 locations, and a comprehensive report will be published tomorrow to guide our winter pollution response. Depending on the results, we are prepared for further cloud seeding sorties in the coming weeks and after the first round of trials, the results will determine whether we should plan more seeding experiments till February.”
The Delhi Government signed an MoU with IIT Kanpur on September 25 to carry out five cloud seeding trials, all in northwest Delhi.
The Directorate General of Civil Aviation had granted permission to conduct them between October and November, following several postponements due to unfavourable weather earlier this year.
This is the third such experiment since 1957 and was carried out after a gap of 53 years from the second experiment. The 1971–72 trial, carried out from the National Physical Laboratory campus, covered a 25-km radius over central Delhi and used silver iodide particles released from ground-based generators to encourage rainfall. An IITM report noted that seeding was conducted on 11 days between December 1971 and March 1972, with 11 additional days kept as controls.
Preliminary data showed an increase in rainfall on the seeded days, suggesting the potential effectiveness of artificial rain under suitable weather conditions. Since then, cloud seeding research in India has expanded.
Cloud seeding involves dispersing cloud-forming particles such as silver iodide or salts into clouds to enhance precipitation. The technique, used in over 50 countries, including China, the US, Russia, and Australia, is deployed for weather modification, rainfall enhancement and pollution mitigation.
Cloud seeding is an advanced weather modification science, intended to trigger or enhance rainfall from suitable clouds by introducing selected particles—such as silver iodide or sodium chloride—using aircraft or other means.
For these trials, specially prepared chemical flares were ignited aboard a Cessna plane and dispersed into promising cloud systems over Delhi. The added materials act as nuclei for condensation, promoting the formation of water droplets and, under the right conditions, rain.
Air quality improves
New Delhi: Delhi's air quality improved slightly to the 'poor' category on Tuesday, with the Air Quality Index dropping to 294 at 4 pm, according to the Central Pollution Control Board (CPCB).
In the morning, the Air Quality Index (AQI) stood in the 'very poor' category with a reading of 305. A thin veil of haze hung over the city.
However, 16 of the national Capital's 38 monitoring stations reported 'very poor' air quality in the evening, as against 27 in the morning.
Siri Fort remained the most polluted location with an AQI of 347, followed by Wazirpur at 332. In the morning, Siri Fort saw a reading of 351 and Wazirpur 342, according to the CPCB's Sameer app.