IIT Kanpur tried cloud seeding despite ‘no clouds’ alert, Pg 8.

Key Highlights:

• On October 28, 2025, IIT Kanpur conducted two cloud seeding attempts over Delhi using a Cessna aircraft to induce artificial rain.
• The IMD had cautioned that there were no suitable clouds for seeding, as moisture levels were below 15%, making rain formation unlikely.
• The experiment involved spraying 10 kg of silver iodide, common salt, and rock salt mixture into the clouds.
• This was Delhi’s first cloud seeding attempt since 1972, specifically aimed at improving air quality.
• Both attempts failed to produce rainfall, confirming IMD’s initial assessment.
• IIT Kanpur defended the experiment as a trial to test the potency of their indigenously developed salt mixture for future use.

Detailed Insights:

• About Cloud Seeding:
  • A weather modification technique where aerosol particles (like silver iodide or sodium chloride) are dispersed into clouds to induce precipitation.
  • Effective only on ‘warm clouds’ containing minimum moisture and suitable condensation nuclei.
• Institutional Coordination:
  • IMD and IITM Pune, India’s lead agencies in atmospheric research, had advised against the experiment due to unfavourable cloud conditions.
  • Despite negative feedback, IIT Kanpur proceeded to test its proprietary solution comprising 20% silver iodide.
• Past Studies & Efficacy:
  • The IITM-CAIPEEX (Cloud Aerosol Interaction and Precipitation Enhancement Experiment) has studied cloud seeding since 2009 but found no conclusive evidence of consistent success.
  • Cloud seeding has shown better results in China and UAE, but success depends heavily on cloud moisture content and atmospheric conditions.
• Results and Analysis:
  • Both sorties failed as targeted clouds dissipated before seeding could take effect.
  • IIT Kanpur stated that the data gathered would aid in refining future seeding operations.
  • Globally, seeded clouds show an average 40–50% increase in rainfall when done under optimal conditions, but Indian trials remain inconclusive.
• Policy Significance:
  • The event highlights the need for inter-agency coordination and scientific validation before large-scale deployment of geoengineering experiments.
  • It also reflects the increasing policy interest in artificial rain to mitigate urban air pollution episodes.

Scientific/Technical Concepts Involved:

• Cloud Seeding: Artificial induction of rainfall using chemical agents like silver iodide, potassium iodide, or sodium chloride to provide condensation nuclei.
• Warm Clouds: Clouds containing sufficient supercooled water droplets essential for seeding-induced rainfall.
• CAIPEEX Project: Ongoing MoES–IITM initiative studying aerosol–cloud interactions and precipitation enhancement in India.