Delhi’s winter air isn’t ideal for cloud seeding, according to a study from IIT Delhi released on October 31. The research, titled “Can Cloud Seeding Help Tackle Delhi’s Air Pollution?”, looked into recent trials by the Delhi government and IIT Kanpur that aimed to create artificial rain. Unfortunately, these attempts showed no significant results.
The study highlighted a major issue: Delhi’s winter climate often lacks the necessary moisture and humidity. During the worst pollution days, when cloud seeding might be most helpful, the atmosphere is typically too dry.
Researchers analyzed ten years of weather data from 2011 to 2021. They only found 92 viable days for cloud seeding in that span. As the study notes, “The success of any seeding operation is fundamentally constrained by pre-existing atmospheric conditions.” Simply put, without adequate humidity and cloud cover, cloud seeding is unlikely to work.
Most of Delhi’s winter rainfall comes from Western Disturbances, which are irregular. These disturbances accounted for only about 15% of the city’s overall winter rainfall between 2011 and 2021. Alarmingly, climate change is making these disturbances even less frequent.
As temperatures drop in winter, the conditions for effective cloud seeding also change. In October and November, the temperature often drops to zero degrees Celsius, allowing for hygroscopic seeding. This method involves adding a mixture from below the base of the clouds to stimulate rainfall. By December and January, temperatures can drop below freezing, making glaciogenic seeding the only option available. This type of seeding typically focuses on enhancing snowfall or cold rain.
The study also explored the effectiveness of cloud seeding on air pollution. Researchers found that while heavy rainfall can significantly reduce PM2.5 levels, these improvements are temporary. Air quality often rebounds to poor levels within just a few days after rain.
In summary, the authors concluded that cloud seeding should not be prioritized for tackling Delhi’s winter air pollution. It’s more of a high-cost, short-term solution rather than a reliable strategy.
For further reading on air quality management, you can check this government report on air pollution.
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