Flawed Cloud Seeding Attempt in Delhi – What is the concept and why did it not work out

On 28th October, 2025 the authorities in Delhi NCR in collaboration with IIT Kanpur, began seeding clouds as a response to the alarming poor quality of air to induce artificial rain and bring down pollution levels in the capital but it turned out to be an unsuccessful attempt due to lack of pre-existing moisture in the clouds.

The Cessna aircraft was sent out on Tuesday afternoon in two phases to disperse salt-based silver iodide flares and seed the clouds covering areas around Burari, Khera, Mayur Vihar, Karol Bagh and neighbouring sites.

But due to minimal moisture in the clouds, little to no rain was seen. Although, the efforts did help in reducing the particulate matter concentrations temporarily to some extent and further gave important insights regarding the required optimal conditions for successful trials in the future .

What is Cloud Seeding?

Cloud seeding is a process of altering or enhancing a cloud’s natural ability to produce rain by introducing particles, like silver iodide mixed with sodium chloride or other salt-based compounds, into moisture filled clouds.

These particles are dispersed through an aircraft to supercooled clouds, and act as nuclei and condense smaller cloud droplets into larger raindrops, giving a nudge to the rain-making process, thus leading to artificial rain.

The essential requirements for a successful attempt are:

1. Cloud Presence: The skies above target sites shouldn’t be clear.
2. Enough moisture in the clouds:A minimum of 50%-60% relative humidity is required.
3. Appropriate cloud temperature: The clouds need to be at temperatures around  -5°C or colder.

Why did the Attempt fail and what is the Plan of Action now?

Rain was expected after 20-30 minutes of not one but two cloud-seeding attempts but this did not happen due to low moisture content(15%-20%) in the clouds which is much lesser than the minimum of 50%.These required conditions are hard to meet during the current winter-transitioning weather in Delhi NCR.

9-10 such trials were scheduled over 28-30th October which have now been put on hold until the conditions are favourable again.

Why the Cloud Seeding Attempt wasn’t completely in vain

Even though little to no rain came out of the cloud seeding trials, it cannot be considered as a complete failure.

The below graph (data source: AQI.in) gives notable insights about the PM levels.

The stations included for analysis are ITI Jahangirpuri, Mayur Vihar and Karol Bagh, some of the few areas where the impact of cloud seeding would be expected to be more pronounced.

1. Observing the trend during the afternoon of 28th October, there is a significant dip in the particulate matter (PM10 and PM2.5) concentrations as compared to the trends before and after.
2. Data shows about 15-18% improvement in PM2.5 levels and 17-19% improvement in PM10 levels post cloud-seeding trials.
3. The rise in PM levels the next day, when the trial was scheduled but did not take place, shows that even a “flawed” attempt helped with the improvement of air quality.
4. It also shows that the impact is rather short lived and multiple trials are required to actually see an impactful difference.

Effects and Long-Term Limitations

A successful attempt would help reduce the air pollution by a significant amount making the air more breathable and less toxic. It would help disperse the smog, haze and particulate matter suspended in the air which would help calm down the deteriorating air quality, a matter of top priority right now in Delhi NCR.

There are however certain concerns regarding chemical accumulation in the atmosphere and ecological disruptions which can impact the ecosystem negatively in the long run if not taken care of or regulated during the procedure. Another limitation of this is being extremely condition-dependent – it is not a guaranteed rain switch as it requires very specific conditions to actually work.

Conclusion

The recent cloud seeding experiment in Delhi, though did not yield the desired rainfall, it definitely did give valuable insights regarding the existing atmospheric conditions and potential improvements in planning the future trials.

Insights suggested that even partial technological interventions in this sector offered some, even though short-lived, relief from the toxic air.

With insights from these trails and more careful future deployment, we can very much expect this to be a success story, helping the capital in its battle with air pollution.