Recent Developments:
- On 13 November 2026, Delhi experienced another episode of hazardous air pollution, with several monitoring stations recording an Air Quality Index (AQI) above 400, falling in the severe category.
- Delhi authorities are preparing further cloud-seeding trials in collaboration with the Indian Institute of Technology, Kanpur, to explore artificial rainfall as a temporary pollution-control measure, subject to favourable meteorological conditions.
- During the preceding 15 days, two cloud-seeding trials were reportedly conducted near the Indira Gandhi International Airport. Further operations were being considered after Diwali and Chhath.
- Earlier trials conducted in October 2025 failed to produce measurable rainfall. Although preliminary claims suggested a reduction in particulate matter, monitoring data indicated that pollution levels had already declined before the operations and subsequently fluctuated.
- The Union Government clarified in February 2026 that the Delhi Government and IIT Kanpur were implementing the pilot project, titled Technology Demonstration and Evaluation of Cloud Seeding as an Alternative for Delhi-NCR Pollution Mitigation, and that the project remained at the trial stage.
Understanding Cloud Seeding:
Definition and Objectives:
- Cloud Seeding is a weather-modification technique that involves introducing specific chemical substances, known as seeding agents, into existing clouds to modify or enhance precipitation.
- It attempts to accelerate natural rainfall or snowfall processes and is used experimentally for drought management, hail suppression and fog dispersal.
- Cloud seeding cannot independently create clouds or generate rain in clear skies; its effectiveness depends on the presence of suitable clouds and favourable atmospheric conditions.
Types of Cloud Seeding:
- Glaciogenic Seeding: Uses ice-nucleating substances such as silver iodide (AgI) to promote ice-crystal formation in cold or supercooled clouds, potentially enhancing snowfall or rainfall.
- Hygroscopic Seeding: Introduces moisture-attracting particles such as sodium chloride (NaCl) into suitable warm clouds to encourage the growth of water droplets through collision and coalescence.
Mechanism of Cloud Formation and Precipitation:
- Natural Rainfall Process:
- Atmospheric water vapour condenses around Cloud Condensation Nuclei (CCN), such as dust, sea salt and smoke particles, forming tiny cloud droplets.
- These droplets grow through further condensation and collision with other droplets, eventually becoming sufficiently large to fall as precipitation.
- In colder clouds, ice crystals form around ice nuclei through freezing or deposition of water vapour. These crystals grow and fall as snow or melt into rain.
- Artificial Cloud Seeding Process:
- Seeding agents are dispersed into suitable clouds through aircraft, drones or ground-based generators and act as artificial cloud condensation nuclei or ice nuclei.
- These particles facilitate the formation and growth of water droplets or ice crystals, potentially accelerating precipitation.
- Once the droplets or ice crystals attain sufficient size, they may fall as rain or snow, depending on atmospheric conditions.
Application of Cloud Seeding in Air Pollution Control:
Wet Deposition and Pollutant Removal:
- Washout Effect: Falling raindrops intercept suspended particulate matter, including PM2.5, PM10, soot, sulphates and other aerosols, and carry them towards the ground.
- Wet Deposition: Precipitation removes atmospheric pollutants and deposits them on land and other surfaces, potentially reducing particulate concentrations.
- Temporary AQI Improvement: Removal of suspended particles can improve air quality and visibility for a limited period, depending on rainfall intensity, pollutant sources and atmospheric conditions.
- Limitation: Rainfall primarily removes pollutants from the atmosphere rather than eliminating their sources. Continued emissions can rapidly restore high pollution levels.
Meteorological Conditions Required for Cloud Seeding:
Cloud Characteristics:
- Pre-existing Cloud Cover: Suitable clouds must already exist because cloud seeding cannot generate precipitation from a clear atmosphere.
- Cloud Depth: Target clouds require adequate vertical development and appropriate microphysical characteristics to support droplet or ice-crystal growth.
- Moisture Availability: Sufficient liquid water content or supercooled water is essential for effective seeding.
Atmospheric and Regional Conditions:
- Temperature: Glaciogenic seeding requires suitable cold-cloud conditions, whereas hygroscopic seeding operates in appropriate warm clouds.
- Wind Conditions: Wind speed and direction influence the movement of seeded clouds and the geographical distribution of precipitation.
- Western Disturbances: These extratropical weather systems originating in the Mediterranean region can bring winter precipitation and suitable cloud formations to northwestern India.
- Meteorological Forecasting: Reliable atmospheric observations and weather forecasts are necessary to identify suitable cloud systems and determine the timing of operations.
Limitations and Challenges of Cloud Seeding:
Scientific and Operational Limitations:
- Uncertain Effectiveness: Natural variations in cloud behaviour make it difficult to distinguish precipitation caused by seeding from rainfall that would have occurred naturally.
- Weather Dependency: Success depends on cloud structure, moisture availability, temperature and wind conditions, which cannot be controlled by the operator.
- Short-Term Pollution Relief: Rainfall can temporarily reduce particulate pollution, but pollutant concentrations may rise again because of continued emissions from vehicles, industries, construction and biomass burning.
- Limited Applicability: Shallow or moisture-deficient winter clouds over Delhi may not provide suitable conditions for significant precipitation.
- Difficult Evaluation: Establishing the effectiveness of cloud seeding requires controlled experiments, untreated comparison cases, atmospheric measurements and statistical analysis.
Economic and Environmental Concerns:
- High Operational Costs: Specialised aircraft, chemical flares, trained personnel, aviation fuel and meteorological monitoring make cloud-seeding operations expensive.
- Ecological Uncertainty: Although available studies have generally not identified significant environmental or human-health impacts from conventional quantities of commonly used silver iodide, prolonged or substantially increased use requires environmental assessment.
- Downwind Effects: Changes in precipitation distribution and possible ecological consequences require further scientific investigation.
- Carbon Footprint: Aircraft operations consume aviation fuel, while the use of dry ice releases carbon dioxide into the atmosphere.
- Opportunity Cost: Excessive dependence on emergency weather-modification experiments may divert attention and resources from sustained emission-reduction measures.
Delhi's Cloud-Seeding Experiments:
October 2025 Trials:
- The Delhi Government collaborated with IIT Kanpur to conduct experimental cloud-seeding operations using a small aircraft equipped with chemical flares containing silver iodide and sodium chloride.
- The operations covered locations including Burari, Mayur Vihar, Karol Bagh and surrounding areas.
- The experiments did not produce measurable rainfall over Delhi.
- Preliminary assessments claimed reductions in PM2.5 and PM10 concentrations, but independent examination of monitoring data showed that pollution levels had declined before the operations and fluctuated afterwards.
- The findings highlighted the difficulty of establishing a direct causal relationship between cloud seeding and changes in air pollution.
Current Pilot Project:
- In February 2026, the Ministry of Earth Sciences informed Parliament that the Delhi Government, in collaboration with IIT Kanpur, was implementing a pilot project to evaluate cloud seeding as an alternative for Delhi-NCR pollution mitigation.
- The project remained at the experimental stage and was intended to provide an additional emergency option during severe pollution episodes when suitable cloud cover was present.
- The Ministry of Earth Sciences clarified that it was not directly involved in the ongoing cloud-seeding operations undertaken by different agencies.
Global Examples of Cloud-Seeding Programmes:
- United Arab Emirates: Conducts cloud-seeding operations to enhance rainfall, support water security and replenish groundwater resources.
- Australia: Uses cloud seeding in selected regions, including Tasmania and the Snowy Mountains, to augment water availability and hydropower generation.
- United States: States such as California, Colorado and Texas use cloud seeding to enhance mountain snowpack and support reservoirs, irrigation and drought management.
- China: Operates large-scale weather-modification programmes using aircraft, drones and other delivery systems for rainfall enhancement, drought mitigation and hail suppression.
- Global Scientific Position: The World Meteorological Organization (WMO) encourages scientifically designed research and rigorous evaluation of weather-modification programmes rather than assuming that cloud seeding will produce guaranteed results.
Alternative Measures for Air Pollution Control:
Technological Interventions:
- Wind Augmentation Purifying Unit (WAYU): Developed by the Council of Scientific and Industrial Research – National Environmental Engineering Research Institute (CSIR-NEERI), these devices use fans and filtration systems to reduce particulate pollution at selected urban locations.
- Smog Towers: These structures draw polluted air through filtration systems, including high-efficiency particulate air filters, to remove some suspended pollutants. Their effectiveness is generally localised and cannot independently address city-wide pollution.
- Photocatalytic Coatings: Materials containing Titanium Dioxide (TiOâ‚‚) use sunlight to initiate chemical reactions that can help remove certain atmospheric pollutants, including nitrogen oxides, from exposed surfaces.
- Anti-Smog Guns and Mist Cannons: These devices spray fine water droplets into the atmosphere to suppress airborne dust and particulate matter, particularly around construction sites and mining areas. Their impact is generally localised.
- Artificial Intelligence-Based Traffic Management: Integration of Artificial Intelligence (AI) and the Internet of Things (IoT) can optimise traffic movement, reduce vehicle idling and lower localised vehicular emissions.
Agricultural and Ecosystem-Based Interventions:
- Pusa Decomposer: Developed by the Indian Council of Agricultural Research (ICAR), this microbial formulation accelerates the decomposition of paddy stubble and converts agricultural residue into organic matter, reducing the need for stubble burning.
- In-Situ Stubble Management: Promoting machinery such as Happy Seeders and Super Straw Management Systems (Super SMS) can help manage agricultural residues without burning them in Punjab, Haryana and Uttar Pradesh.
- Urban Greening: Developing urban forests through approaches such as the Miyawaki Method, green corridors and roadside plantations can help intercept dust and improve urban ecological conditions.
Structural and Transport Reforms:
- Clean Mobility: Expanding electric-vehicle adoption, strengthening public transportation and promoting non-motorised mobility can reduce emissions from road transport.
- Industrial Emission Control: Strengthening emission standards, pollution-control equipment and continuous emission monitoring can reduce industrial contributions to particulate and gaseous pollution.
- Construction Dust Management: Mandatory dust suppression, covering construction materials, mechanised road sweeping and effective debris management can reduce resuspended particulate matter.
Institutional Framework for Air Pollution Control in India:
Commission for Air Quality Management:
- The Commission for Air Quality Management (CAQM) was established under the Commission for Air Quality Management in National Capital Region and Adjoining Areas Act, 2021.
- It coordinates air-quality management across Delhi-NCR and adjoining areas and can issue binding directions to relevant authorities.
- Section 12 empowers the Commission to take measures and issue directions necessary for protecting and improving air quality.
Graded Response Action Plan:
- The Graded Response Action Plan (GRAP) provides a graded framework of preventive and restrictive measures based on different levels of air pollution.
- It includes measures relating to construction activities, industrial operations, vehicular emissions and other pollution-generating activities.
- The CAQM revised the GRAP framework in September 2026 and directed precautionary interventions in Delhi-NCR during 5–20 November 2026 to reduce pollution during the seasonal peak.
- The framework emphasises preventive action and reduction of emissions at source rather than relying exclusively on emergency interventions.
Scientific Monitoring and Forecasting:
- The Ministry of Earth Sciences has highlighted the development of AIRWISE (Air Quality Warning and Integrated Decision Support System for Emissions) by the Indian Institute of Tropical Meteorology in collaboration with the India Meteorological Department.
- The framework integrates air-quality monitoring, emissions inventories, source apportionment and predictive modelling to support evidence-based pollution-control decisions.
- Improved PM2.5 forecasting and measurement-based source apportionment can help authorities identify major pollution sources and implement targeted interventions.
Way Forward:
- Source-Based Pollution Control: Prioritise reductions in vehicular, industrial, construction, power-generation and agricultural emissions rather than depending primarily on artificial rainfall.
- Scientific Evaluation: Conduct controlled cloud-seeding experiments with transparent data, untreated comparison cases and independent assessment of environmental and meteorological outcomes.
- Regional Coordination: Strengthen cooperation among Delhi, Punjab, Haryana, Uttar Pradesh and Rajasthan because air pollution crosses administrative boundaries.
- Agricultural Transition: Expand affordable residue-management machinery, crop diversification and incentives for alternatives to stubble burning.
- Clean Energy and Transport: Accelerate renewable energy adoption, cleaner industrial fuels, electric mobility and reliable public transportation.
- Institutional Accountability: Strengthen the CAQM, pollution-control boards, municipal bodies and local administrations through measurable targets and regular monitoring.
Value Addition for UPSC:
Important Scientific Concepts:
- Cloud Condensation Nuclei (CCN): Atmospheric particles around which water vapour condenses to form cloud droplets.
- Ice Nuclei: Particles that facilitate the formation of ice crystals in suitable cold-cloud conditions.
- Wet Deposition: Removal of atmospheric pollutants through precipitation, including rain and snow.
- Atmospheric Inversion: A meteorological condition in which temperature increases with altitude over a particular layer, restricting vertical atmospheric mixing and trapping pollutants near the surface.
- Aerosols: Solid or liquid particles suspended in the atmosphere, which influence air quality, visibility and cloud formation.
- Source Apportionment: Scientific assessment of the relative contribution of different sources to air pollution in a particular region.
Relevant Institutions and Programmes:
- World Meteorological Organization: Provides scientific guidance and encourages evidence-based research on weather modification.
- Central Pollution Control Board: Coordinates pollution monitoring and implements environmental standards under applicable laws.
- Commission for Air Quality Management: Coordinates air-pollution mitigation measures across Delhi-NCR.
- National Clean Air Programme (2019): Seeks to improve air quality through city-specific action plans, monitoring and emission-reduction interventions.
- National Air Quality Index: Provides a standardised measure of ambient air quality based on concentrations of major air pollutants.
UPSC Syllabus Linkage:
- GS Paper III: Environmental pollution and degradation, conservation, science and technology, environmental impact assessment and disaster management.
- GS Paper II: Statutory bodies, environmental governance, Centre-State coordination and government interventions.
- Essay: Urbanisation, public health, environmental sustainability and the relationship between technological innovation and ecological governance.
Key Takeaway:
- Cloud seeding may provide temporary and conditional relief from particulate pollution, but it cannot replace sustained emission reduction. Delhi's air-pollution strategy must prioritise source identification, regional coordination, clean mobility, agricultural-residue management and effective enforcement of environmental regulations.
