Daily UPSC Mains Question - GS 3 - 4th November 2025

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QUESTION

Evaluate the environmental consequences and scientific feasibility of chemical cloud seeding in urban regions like Delhi. Also discuss the potential applications and limitations of such weather-modification techniques in India.

Answer:

Cloud seeding is a weather modification technique that aims to enhance precipitation by dispersing chemical agents such as silver iodide, potassium iodide, or sodium chloride into clouds, serving as artificial nuclei for condensation. In India, the idea of using cloud seeding to reduce air pollution and alleviate smog in urban centers like Delhi has been proposed periodically. However, the scientific feasibility and environmental implications of such an intervention require critical evaluation.

Environmental Implications of Using Chemical Cloud-Seeding Agents in Urban Areas

1. Chemical Contamination of Air and Water:

   • Common cloud-seeding agents like silver iodide (AgI) and potassium iodide (KI) are toxic heavy metal compounds in large concentrations.

   • Overuse could lead to bioaccumulation in soil, surface water, and vegetation, posing long-term ecological and health hazards.

2. Impact on Atmospheric Chemistry:

   • Artificial alteration of cloud microphysics can disturb the natural aerosol balance, influencing regional weather patterns and rainfall distribution beyond the targeted area.

   • Potential downwind effects such as acidification of rainwater or reduced rainfall elsewhere may occur due to atmospheric perturbations.

3. Ineffectiveness During Post-Monsoon Conditions:

   • The India Meteorological Department (IMD) classifies October–December as the post-monsoon season, marked by absence of moisture-laden monsoon clouds and calm wind conditions.

   • According to the Ministry of Earth Sciences (MoES), cloud seeding during this period is largely ineffective as mature convective clouds—necessary for precipitation—are missing.

4. Urban Microclimate Alterations:

   • In densely populated regions, excessive moisture injection can lead to localised flooding, waterlogging, and urban heat island amplification once the water evaporates.

5. No Established Data for Northern Indian Plains:

   • The MoES notes the lack of scientific data to confirm effective rainfall induction through seeding in Delhi-NCR’s winter conditions, unlike results obtained from southern India.

Scientific and Empirical Evidence from Past Indian Experiments

The Ministry of Earth Sciences (MoES) and the Indian Institute of Tropical Meteorology (IITM) have conducted the Cloud Aerosol Interaction and Precipitation Enhancement Experiment (CAIPEEX) in four phases (2009–2019) across southern peninsular India.

Findings from CAIPEEX:

• Rainfall enhancement up to 46% (with a deviation of ±13%) in localized regions.

• An average increase of 18% (±2.6%) in rainfall over a 100 sq. km area downwind of the seeded zone.

• The findings led to the development of national guidelines and protocols for cloud seeding to ensure scientific and ethical conduct.

These results suggest that successful cloud seeding depends critically on:

• Presence of convective clouds

• Favourable humidity and temperature

• Accurate weather modeling and monitoring

Potential Applications of Weather Modification Techniques

1. Rainfall Enhancement:

   • Used to augment rainfall in drought-prone regions or enhance reservoir catchment inflow.

   • Particularly beneficial in agriculture, hydropower generation, and groundwater recharge projects.

2. Fog and Smog Suppression:

   • Artificial nucleation can aid in fog dispersal around airports or highways, improving visibility during winter months.

3. Hail and Rainfall Suppression:

   • Overseeding (injecting excess nuclei) can reduce hailstorm intensity by forming numerous smaller ice particles instead of a few large hailstones.

4. Marine Cloud Brightening and Climate Engineering:

   • Experimental use in geoengineering aims to increase cloud albedo (reflectivity) to reflect sunlight and mitigate global warming impacts.

5. Disaster Management Applications:

   • Controlled rainfall induction can be employed in forest fire management or dust storm mitigation.

Challenges and Limitations

• Scientific uncertainty in outcome prediction and success rate.

• High operational costs and dependence on real-time meteorological data.

• Ethical and environmental concerns about large-scale atmospheric modification.

• Absence of uniform global regulation on cross-border weather interventions.

While cloud seeding offers potential in rain enhancement and weather management, its use in densely populated urban areas like Delhi must be scientifically timed and environmentally regulated.Experiments such as CAIPEEX demonstrate that favourable cloud conditions and sound meteorological modeling are prerequisites for success. In the context of India, such technologies should be pursued as part of a broader, evidence-based environmental management strategy, integrating air quality control, sustainable urban planning, and climate adaptation rather than as standalone short-term solutions.

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