Delhi’s Cloud Seeding Trial Postponed to Late August as Monsoon Arrives Early

In a proactive push to clean the city’s polluted skies, the Delhi government has rescheduled its maiden cloud seeding trial—the first-ever in the national capital—from July 4–11 to August 30–September 10, 2025. The reason? An early and active monsoon has dawned, making current weather unsuitable for the scientific experiment.

Delhi’s Environment Minister, Manjinder Singh Sirsa, confirmed the decision on July 2, 2025, emphasizing that the ongoing rainfall would mingle with seeded clouds, skewing the results and masking true outcomes.

Partnering with IIT Kanpur, IITM Pune, and the India Meteorological Department (IMD), the initiative seeks to test cloud seeding’s efficacy in triggering artificial rain—to wash away smog, improve air quality, and explore long-term pollution control techniques.

Why Early Monsoon Disrupts Cloud Seeding

Cloud seeding requires specific atmospheric conditions: unstable clouds rich in moisture but not already yielding natural rainfall. Delhi’s early monsoon has led to:

• Persistent precipitation, making it hard to distinguish between natural and seeded rain.
• Highly saturated clouds, which diminish the impact of seeding and render results scientifically inconclusive.

Experts from IIT Kanpur and IMD analyzed early July’s weather data and advised rescheduling to ensure scientific precision and clarity—essential for evaluating the pilot project's true effectiveness.

New Timeline: August 30 – September 10, 2025

Here’s the updated schedule:

• Window: August 30 – September 10, 2025
• Aircraft: Cessna 206 H (VT IIT), retrofitted with cloud seeding instruments by IIT Kanpur
• Scope:
  • North Delhi: Rohini, Bawana, Alipur, Burari
  • NCR Outskirts: Loni, Baghpat, Kundli border, Eastern Peripheral Expressway regions
• Flights: Five sorties planned under DGCA approved routes and safety norms

These locations are identified hotspots of particulate pollution—ideal for evaluating the rain’s pollutant-washing impact.

Budget & Administrative Clearances

This marks the first time Delhi has secured DGCA clearance for deploying artificial rain technology to tackle air pollution.

What Is Cloud Seeding?

Cloud seeding is a form of weather modification where aircraft release hygroscopic aerosols like silver iodide, iodised salt, or rock salt into the atmosphere. These particles act as condensation nuclei, encouraging moisture in clouds to coalesce and precipitate earlier than it naturally would.

It is used globally in cities like Bangalore, Mumbai, and in countries like China, USA, and UAE for either drought relief or air quality improvement. In Delhi’s case, the goal is to wash out suspended particulate matter (PM2.5/PM10) and temporarily clear the air.

Effectiveness: What Can We Expect?

Research and past trials indicate that cloud seeding can boost rainfall by 5–15%, though actual effectiveness varies widely. In India, some pilots have reported just a 3% increase. This Delhi trial is part of the 2025 Environment Action Plan, aimed at providing a scientific foundation for future pollution-control strategies.

Delhi’s Monsoon Context

Monsoon season in Delhi usually spans July to September, bringing heavy rains and high humidity. The city’s average annual precipitation is around 774.4 mm, with July to September being the wettest period. The early arrival of the monsoon in July 2025 led authorities to postpone the cloud seeding trial to avoid overlapping with natural rainfall patterns.

Why It Matters for Delhi

Delhi faces severe air pollution, especially in winter. While not a permanent fix, cloud seeding can offer:

• Immediate relief by washing pollutants out of the air
• Data for assessing real-time air quality improvements
• A framework for repeat or seasonal implementation if proven effective

IIT Kanpur researchers will monitor rainfall and air quality post-trial. The results will be shared with CPCB, courts, and central agencies for broader scientific and policy evaluation.

Frequently Asked Questions (FAQs)

Q1: Why was cloud seeding rescheduled?

A1: Due to early and active monsoon rainfall in July, which could skew trial results and make it hard to measure seeded rain precisely.

Q2: What is the new trial period?

A2: The postponed window is August 30 to September 10, 2025, expected to have fewer natural rains with suitable clouds.

Q3: Who leads the trial?

A3: The Department of Aerospace Engineering, IIT Kanpur, working with IMD and IITM Pune, under the guidance of Environment Minister Manjinder Singh Sirsa.

Q4: How much does it cost?

A4: The pilot is budgeted at ₹3.21 crore, covering aircraft retrofitting, operations, and monitoring.

Q5: Is DGCA approval obtained?

A5: Yes, DGCA has given aerial work clearance. The trial will not enter restricted zones or involve aerial photography.

Q6: Which aircraft will be used?

A6: A Cessna 206 H (VT IIT) aircraft equipped with cloud seeding instruments developed by IIT Kanpur.

Q7: Will cloud seeding harm the environment or humans?

A7: No. The particles used—silver iodide and salts—are within safety norms and do not pose health risks. All protocols will be followed.

Q8: How effective is cloud seeding in air pollution control?

A8: It may increase rainfall by 5–15%, but outcomes vary. Some Indian trials showed only a 3% increase.

Q9: What will be measured post trial?

A9: Rainfall levels and air quality indicators like PM2.5 and PM10 will be tracked to assess impact.

Q10: Could this be done annually?

A10: If proven beneficial, cloud seeding could be incorporated into Delhi’s winter air pollution response strategy.

Final Analysis & Outlook

Delhi’s decision to reschedule the cloud seeding trial reflects a science-first approach. The government is prioritizing:

• Accuracy—avoiding natural rain interference
• Safety—DGCA approvals and expert-led implementation
• Transparency—with clear budgeting, locations, and trial metrics

If successful, this experiment could serve as a blueprint for pollution control in other urban areas across India.

Report by Toofan Express