Cloud Seeding in Winters to Reduce Pollution is Bad Science, Pg 9.

Key Highlights:

• Cloud seeding involves introducing silver iodide or sodium chloride into clouds to stimulate rainfall.
• Works only with hygroscopic or warm-rain clouds that contain sufficient moisture.
• During winter (Nov–Jan), such clouds are rare—occurring only 10% of the time, making seeding largely ineffective.
• Delhi’s Air Quality Index (AQI) crossed 400 (“Severe”), prompting experimental seeding attempts.
• Experts assert that cloud seeding may temporarily reduce particulate matter but fails to address root causes like vehicular emissions and crop burning.

Detailed Insights:

• Scientific Limitation: Cloud seeding depends on existing cloud types and humidity; winter skies over northern India are typically dry and stable, unsuitable for condensation-based rainfall.
• Short-Lived Impact: Even when successful, drizzle from seeding is insufficient to wash out fine particulates like PM2.5, and pollutants re-accumulate rapidly due to continued emissions.
• False Relief: Reported short-term AQI improvements ignore persistent emission sources and the non-linear rebound in particulate matter levels post-seeding.
• Misplaced Policy Focus: Reliance on quick fixes diverts attention from year-round emission management, including traffic congestion, vehicular exhaust, fossil fuel combustion, and industrial pollutants.
• Systemic Approach Needed: Experts suggest an airshed-level framework, coordinated mitigation, and a transition to electric vehicles and cleaner fuels as long-term solutions.
• Scientific Consensus: As per SAFAR (System of Air Quality and Weather Forecasting and Research), vehicular emissions contribute over 40% of Delhi’s PM2.5 load, compounded by growing vehicle numbers offsetting prior technological gains.

Scientific/Technical Concepts Involved:

• Cloud Seeding: Artificial weather modification technique introducing condensation nuclei (like silver iodide) to induce precipitation.
• PM2.5: Fine particulate matter (<2.5 micrometers) responsible for severe respiratory issues; main pollutant in urban smog.
• Airshed Management: Regional-scale air quality management approach recognizing that pollution transcends administrative boundaries.