In October， during the Diwali festival period， New Delhi， the capital of India， experienced a severe surge in PM2.5 concentrations， exceeding the World Health Organization’s safe limits by over 25 times. The Air Quality Index (AQI) surpassed 500， plunging the city into a “severely hazardous” category.
To address this escalating crisis， the Delhi government partnered with the Indian Institute of Technology (IIT) Kanpur to conduct two cloud seeding experiments. This involved aircraft dispersing silver iodide and sodium chloride particles into the clouds， with the aim of triggering rainfall to help wash away pollutants.
Shortly after the first cloud seeding attempt， Delhi’s Environment Minister， Gopal Rai， stated that IIT Kanpur had predicted rain within 15 minutes to 4 hours post-experiment. However， he also noted that due to low humidity levels， specifically between 15% and 20%， any resulting rainfall would likely be negligible.
Despite these efforts， data from the India Meteorological Department indicated that by the evening of that day， no rainfall was recorded in New Delhi.
Residents in southern Delhi expressed their disappointment， with one noting， “Not a single drop of rain fell from the artificial rain; this is a waste of public funds. My home air purifier shows AQI at 500， far exceeding safe standards.”
The fundamental prerequisite for successful cloud seeding is the presence of sufficient supercooled liquid water in the clouds， requiring a humidity level of at least 50%. However， during the experiments， Delhi’s air humidity was only between 15% and 20%. Furthermore， the region was experiencing the influence of a low-pressure system from the Arabian Sea and a cyclone from the Bay of Bengal， which had significantly drawn moisture away from the area， resulting in exceedingly thin cloud cover.
Experts from the Indian Institute of Tropical Meteorology pointed out that the atmosphere at the time was in a “dry and stable state，” completely lacking the necessary conditions for seeding. Under such circumstances， the dispersed seeding agents could not form effective ice nuclei， leading only to trace amounts of drizzles on the outskirts of Delhi， with no precipitation recorded in the city center.
A research team from IIT Delhi analyzed climate data from 2011-2021 and found that over 90% of winter days in Delhi have humidity below 40%， rendering it inherently unsuitable for artificial rain enhancement. This “doing what is known to be futile” approach has been criticized as “turning science into a tool for political showmanship.”
