Emissions not targeted, gains are small: the challenges of cloud-seeding, Pg4.

Key Highlights:

• An IIT-Kanpur team conducted cloud-seeding flights over Delhi, releasing silver iodide and salt particles to induce rain and reduce pollution.
• Noida recorded 0.1 mm of rain, and Greater Noida reported 0.2 mm, while Delhi experienced no rainfall during the cloud-seeding experiment.
• Experts caution that the effectiveness of cloud seeding in convective, low-level clouds is uncertain, and any air quality improvements are likely short-lived.
• Cloud seeding programs can cost Rs 3.2 crore or more, raising concerns about cost-effectiveness.

Detailed Insights:

• The effectiveness of cloud seeding depends on factors like cloud height, type, moisture content, and timing, which are often not ideal in the plains.
• Air quality analysts emphasize that cloud seeding does not address the root causes of pollution, which require tackling sector-specific emissions.
• The timing of cloud seeding is crucial, as clouds should be targeted early in their growth before they start raining to prevent seed particles from being washed out.
• Delhi's complex aerosol mix, including sulphates and silica dust, can hinder cloud formation, and the process may take several hours with no guarantee of success.
• Environmental impact studies on cloud seeding are limited, but concerns exist regarding the toxicity of silver iodide to aquatic life, even in small amounts.

Scientific/Technical Concepts Involved:

• Cloud Seeding: A weather modification technique that disperses substances into the air to increase precipitation.
• Silver Iodide (AgI): An insoluble substance used in cloud seeding to act as ice nuclei and promote precipitation.
• Hygroscopic: A substance's ability to absorb moisture from the air.