What Is Cloud Seeding? Why Didn't It Cause Rain In Delhi? Here's What The IIT Kanpur Director Said

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As Delhi gasped under a thick grey veil of smog this week, the city's desperate hope turned skyward - quite literally. On Tuesday, scientists from IIT Kanpur, in collaboration with the Delhi government, took to the skies for a bold experiment: cloud seeding to induce artificial rain.

It was a moment charged with anticipation, science, and emotion. But the results? Not quite the downpour Delhi was praying for.

Let's understand what really happened, why it didn't rain, and what this means for Delhi's fight against pollution.

What Is Cloud Seeding And How Does It Work?

Cloud seeding is a weather modification technique that involves injecting substances like silver iodide or salt into clouds to encourage rainfall. The idea is simple but delicate - these particles act as nuclei around which moisture condenses, eventually forming raindrops.

But there's a catch. For this process to work, the clouds themselves need to have sufficient moisture. Without that, no matter how much material you seed, there's just not enough water vapour to create rain. It's science - not sorcery.

Why The Rain Didn't Come: IIT Kanpur Director Explains

Professor Manindra Agarwal, Director of IIT Kanpur, explained in an exclusive conversation with NDTV that the experiment was "not completely successful" on Tuesday. The reason? Low moisture content.

"There hasn't been any rain so far. Unfortunately, the clouds today did not have very high moisture content - only about 15-20%. So, the possibility of causing rain with such low moisture content is not very high," Agarwal said.

Despite this, he described the attempt as a valuable trial. "This experiment has given more confidence to our team that we can continue conducting them when conditions are more favourable," he added.

What Exactly Was Used In The Seeding Process?

Unlike what some might imagine, cloud seeding isn't about spraying mysterious chemicals. The IIT Kanpur team used a mixture that contained just 20% silver iodide, while the rest was a combination of rock salt and common salt. In total, 14 flares were fired into the sky.

While it didn't lead to significant rainfall, Agarwal pointed out that the team's findings are crucial for understanding atmospheric behaviour - especially in a city where weather conditions change rapidly. Two more flights were planned for the following day, depending on cloud cover.

Can Cloud Seeding Solve Delhi's Pollution Problem?

When asked if cloud seeding could serve as a long-term fix for Delhi's chronic air quality issues, Agarwal's answer was clear: "It's an SOS solution."

"This is not a permanent solution," he explained. "When pollution levels are dangerously high, cloud seeding can be attempted as an emergency measure to bring temporary relief. But in the long run, we must address the sources of pollution."

The costs, he admitted, are high - mainly because the flights are conducted from Uttar Pradesh. However, he emphasized that any method that can temporarily reduce pollution offers some benefit. "Even if it rains after a few days, it can still help by settling particulate matter," he noted.

What The Government Report Says

Interestingly, despite the lack of visible rainfall in many areas, the Delhi government's report indicated some positive results. The data showed a drop in particulate matter (PM 2.5 and PM 10) after the seeding.

Before the experiment, PM 2.5 levels in Mayur Vihar, Karol Bagh, and Burari were around 221-230, which later reduced to 203-207. Similarly, PM 10 levels dropped from around 209 to 163-177.

There were also small precipitation readings - 0.1 mm of rain in Noida and 0.2 mm in Greater Noida around 4 PM. It wasn't much, but for scientists, it's proof that the experiment has potential when conditions improve.