Artificial Rain (Cloud Seeding) for Delhi

Main Takeaway: Delhi’s first-ever cloud seeding pilot—scheduled between July 4 and 11, 2025—aims to induce artificial rain to wash out particulate pollution. Led by IIT Kanpur with IMD support, it involves five aircraft sorties deploying a silver iodide–rock salt mixture into moisture-laden Nimbostratus clouds under strict regulatory oversight.

Pilot Design and Timeline

The pilot project, titled “Technology Demonstration and Evaluation of Cloud Seeding as an Alternative for Delhi NCR Pollution Mitigation,” was approved by the Delhi Cabinet on May 7, 2025. Key milestones:

• Flight Window: July 4–11, 2025, contingent on favourable meteorological conditions from the IMD.
• Trials: Five sorties, each lasting ~90 minutes, covering ~100 sq km per flight over north and outer Delhi (Rohini, Bawana, Alipur, Burari) and adjacent UP areas (Loni, Baghpat).
• Budget: ₹3.21 crore allocated (₹2.75 crore for trials; ₹0.55 crore setup.

Scientific Methodology

Cloud seeding leverages glaciogenic and hygroscopic mechanisms to accelerate droplet formation:

• Target Clouds: Nimbostratus at 500–6,000 m altitude with ≥50% moisture content, as identified by IIT Kanpur and IMD data.
• Seeding Mixture: Custom flares containing:
  • Silver iodide nanoparticles
  • Iodized salt
  • Rock salt
  • Free-flowing agent
• Delivery Platform: Modified Cessna aircraft equipped with flare dispensers, operating from Hindon Airforce Station (defence clearance secured).

Regulatory and Monitoring Framework

• Meteorological Coordination: IMD provides real-time data on cloud type, altitude, wind direction, and dew point for flight planning and execution3.
• Flight Clearance: Final approvals pending from DGCA, along with clearances from SPG, CPCB, AAI, BCAS, MoD, MoE, and MoH. Alternate windows requested to accommodate shifting weather.
• Environmental Safety: Post-sortie water samples tested for residual chemical concentrations. Continuous Ambient Air Quality Monitoring Stations will measure PM2.5 and PM10 before, during, and after trials to assess pollution reduction.

Benefits and Limitations

• Pollution Mitigation: Artificial rain can temporarily lower surface PM concentrations by washing particulates from the air column.
• Short-Term Relief: Provides rapid, localized health benefits during high pollution episodes, though efficacy depends on precise cloud conditions.
• Uncertainty Factors:
  • Distinguishing seeded rain from natural precipitation is challenging, but correlation with timing (within one hour) can indicate seeding impact.
  • Dry atmospheric layers or unsuitable cloud types may limit surface rainfall.
  • Long-term air-quality improvements require systemic emission controls alongside such interventions.

Implications for Urban Environmental Management

Cloud seeding in Delhi represents an innovative supplement to anti-smog guns, sprinklers, and dust-mitigation measures. While not a standalone solution, it underscores the government’s commitment to exploring science-driven strategies under the “Right to Clean Air” principle. Outcomes from this pilot will inform future policy on weather modification as a transient tool in comprehensive air-quality management plans.

1. Cloud seeding viable between July 4–11, IMD in report to Delhi govt, Hindustan Times, June 28, 2025.
2. Delhi to conduct five cloud-seeding trials, Swarajya Magazine, May 13, 2025.
3. IMD approves cloud seeding pilot project, The New Indian Express, June 19, 2025