Cloud Seeding Trials in Delhi Show Promise in Reducing Particulate Matter

Delhi witnessed cloud seeding trials on Tuesday, which a recent report indicates, helped reduce particulate matter at targeted locations. The exercise was undertaken despite less than ideal conditions. The initiative marks the third such experiment in Delhi since 1957.

Data collected from 20 locations revealed a decrease in PM2.5 and PM10 levels following the seeding. Two precipitation events were recorded in Noida and Greater Noida. According to an official Delhi government report, the moisture content was low at 10-15 percent, which is not ideal for cloud seeding. Winds were negligible; however, the seeding particles facilitated the settling of pollutants.

The cloud seeding was carried out from airstrips in Kanpur and Meerut. During the trial, a Cessna 206H aircraft released six flares at an altitude of nearly 4,000 feet, with a burn duration of 18.5 minutes in the first round. A second flight deployed eight flares at a higher altitude of around 5,000-6,000 feet.

Delhi's Environment Minister, Manjinder Singh Sirsa, informed that eight flares were used for the process. He added that rain may be expected anytime between 15 minutes to four hours, though the location and intensity cannot be pre-determined. A third cloud seeding trial is also planned.

Cloud seeding involves dispersing chemicals like silver iodide nanoparticles, potassium iodide, and dry ice into clouds to accelerate water droplet formation. Once the droplets become heavy enough, they fall as rain.

Environmentalists have termed the cloud-seeding trial a short-term measure, saying it may temporarily reduce pollution but will not address the root causes of the capital's deteriorating air quality. They believe that while rain can subside pollution, it is only a temporary solution that might provide relief for a few days.

This trial is part of the Delhi government's broader strategy to mitigate deteriorating air quality during the winter months. The Delhi Cabinet approved the plan on May 7, allocating Rs 3.21 crore for five trials.

Cloud seeding has been used in over 50 countries for weather modification, rainfall enhancement, and pollution mitigation. The Delhi project, cleared by the Directorate General of Civil Aviation (DGCA), aims to evaluate whether artificial rain can reduce pollution in the coming years.

The first cloud seeding experiment in Delhi was conducted during the monsoon of 1957, and the second in the early 1970s. The 1971–72 trial covered a 25-km radius over central Delhi and used silver iodide particles released from ground-based generators to encourage rainfall. Preliminary data showed an increase in rainfall on the seeded days, suggesting the potential effectiveness of artificial rain under suitable weather conditions.