Cloud Seeding in Delhi

Why in the news?

• Amid rising pollution levels, in October 2025, the Delhi government, in collaboration with the Indian Institute of Technology (IIT) Kanpur, carried out two cloud seeding trials to induce artificial rainfall. However, only negligible precipitation was recorded till late evening.
• A Cessna 206H aircraft conducted cloud seeding trials to induce artificial rain. Earlier, the Capital recorded an AQI of 294, in the ‘Poor Category’.

Cloud seeding holds significant relevance for the UPSC exam syllabus. It mainly deals with the subjects of Geography, Environment, Science and Technology, and Current Affairs. As a weather modification technique, it links scientific innovation with pressing environmental issues such as air pollution, drought management, and climate change adaptation. Understanding the principles, methods, benefits, and challenges of cloud seeding helps aspirants analyze India’s responses to environmental crises, particularly in cities like Delhi, facing severe air pollution.

What is Cloud Seeding?

• Firstly, cloud seeding is a weather modification intervention that aims to artificially alter the amount or type of precipitation. 
• Its objective is to induce or increase the rate of precipitation, which the Delhi Government hopes will help to reduce air pollution.
• Chemical ‘seed’ particles are used to modify clouds. 
• The seeds act as ‘cloud condensation nuclei’ around which water vapour condenses. When droplets have grown large enough, they fall as rain.
• These help water droplets form and grow, eventually falling as rain.

About the Technique of Cloud Seeding:

• The technique is about 75 years old. Different methods are used for different cloud base temperatures. 
• Particles are released below the base of cumulus clouds that have a warm base (temperature above zero degrees), while cold clouds are top-seeded hygroscopic and glaciogenic seeding, respectively.
• Commonly used cloud seeding agents are chlorides of sodium, potassium, and calcium and the iodide of silver.

Different Methods of Cloud Seeding

• Hygroscopic Cloud Seeding: 
  • This method involves dispersing salt particles, such as sodium chloride or potassium chloride, into the lower layers of clouds, often using explosives or flares. 
  • These salts attract moisture, helping water droplets grow larger and eventually fall as rain.
• Static Cloud Seeding: 
  • In this technique, fine particles like silver iodide are released into clouds to act as nuclei around which moisture condenses. 
  • This promotes droplet formation and enhances the likelihood of rainfall.
• Dynamic Cloud Seeding: 
  • This approach aims to strengthen vertical air currents within clouds, allowing more moisture to rise and condense. 
  • As a result, cloud thickness and rainfall potential increase significantly.

What are the Requirements for Cloud Seeding?

• The availability of clouds is a basic requirement. Rain is not possible in a cloudless sky.
• Availability of moisture is also very important.
• Further, the cloud must have an optimum level of instability (convection). 
• These conditions allow the vertical growth of clouds.
• If horizontal winds are too strong, they may prevent the cloud from growing tall.
• In short, growing cumulus or deep convective clouds with moderate instability and sufficient moisture and conditions that are not too windy are suitable.

What are the Challenges of Cloud Seeding?

• Its timing is important. Clouds must be targeted in the early period of their growth. According to a 2023 report by the Indian Institute of Tropical Meteorology, clouds must be targeted early in their development stage before natural rainfall begins.
• Seeding in raining clouds will wash out seed particles into the boundary layer.
• The pilot must be trained, as flying in upper level clouds can lead to icing on aircraft.
• The timing, cloud type and moisture must align almost perfectly. These conditions often do not hold over the plains.
• Seeding does not target emission at the source. Addressing air quality requires sector-specific emissions prevention measures.
• Cosmetic measures like smog towers, anti-smog guns, or cloud seeding may create short term visible benefits but are not sustainable solutions.
• The method needs pre-existing cloud formation, relative humidity above 50% and lower temperatures to hasten precipitation.
• Silver iodide, a key chemical used in cloud seeding, is insoluble and its long-term environmental effects remain uncertain. Even in small concentrations, it can be highly toxic to fish, aquatic microorganisms, and other forms of life, raising ecological safety concerns.

Findings of IITM Pune on Cloud Seeding:

• The Indian Institute of Tropical Meteorology (IITM), Pune conducted cloud seeding experiments across different environmental conditions, comparing seeded clouds with unseeded ones.
• The study observed an 80% increase in rainfall in the seeded clouds, indicating the potential effectiveness of the technique under favourable conditions.
• Additionally, the seeded clouds exhibited longer lifespans, sustaining precipitation for extended periods.
• Researchers emphasized that accurate identification of suitable clouds and appropriate seeding materials is crucial, as not all cloud types are suitable for seeding.

Benefits of Cloud Seeding:

• Reducing Air Pollution: Cloud seeding is a scientific intervention that can help temporarily alleviate air pollution by inducing rainfall, which washes away airborne pollutants and dust particles.
• Enhancing Snowfall and Water Availability: By increasing winter snowfall and mountain snowpack, cloud seeding helps boost natural water reserves, ensuring an improved water supply for nearby communities and ecosystems.
• Boosts Water Resources: It helps refill reservoirs, rivers, and groundwater, ensuring better water supply for domestic and industrial use.
• Supports Weather Modification Research: It contributes to scientific understanding of weather patterns, aiding in climate studies and disaster management planning.

Why is Delhi Considering Cloud Seeding?

• Delhi experiences very poor and even severe air-quality episodes, especially in winter, when pollutants like PM2.5 and PM10 accumulate under stagnant weather conditions.
• Therefore, the Delhi government has proposed cloud seeding as an emergency intervention to trigger artificial rain and wash away suspended particulates.

The Policy Process & Stakeholders:

• In May, 2025 the Delhi Cabinet approved cloud-seeding trials costing about ₹3.21 crore, in collaboration with IIT Kanpur.
• Clearances from multiple agencies gave their clearances for the trials. The Directorate General of Civil Aviation gave its clearance for flights over designated zones between October and November, 2025.
• Key agencies such as the Central Pollution Control Board (CPCB) and India Meteorological Department (IMD) have raised concerns about feasibility.

Concerns Associated with Cloud Seeding:

• Lack of Reliable Data: Limited and inconsistent scientific evidence on the success rate of cloud seeding operations. makes it difficult to assess their true effectiveness or justify the investment.
• Issues with Seeding Materials: The commonly used compound, silver iodide, poses potential toxicity risks to both terrestrial and aquatic ecosystems. This concern has led researchers to explore safer, eco-friendly alternatives.
• Environmental Risks: If cloud seeding coincides with already heavy rainfall, it can intensify precipitation and trigger floods, causing damage to infrastructure, agricultural fields, and livelihoods.

Conclusion:

In conclusion, cloud seeding in Delhi represents a bold scientific attempt to counter severe air pollution and water scarcity challenges. The recent trials conducted by the Delhi Government in collaboration with IIT Kanpur reflect India’s growing interest in weather modification as a short-term environmental intervention. However, experts continue to debate its effectiveness, cost-efficiency, and environmental safety. While cloud seeding can temporarily improve air quality, it cannot replace long-term measures like curbing vehicular emissions, regulating industrial discharge, or controlling stubble burning.

For aspirants of UPSC, APSC, and other State PCS Exams, understanding this topic is extremely important. It connects multiple parts of the syllabus—Geography, Environment, Science & Technology, and Current Affairs. Moreover, questions related to climate engineering, sustainable solutions, and pollution management often appear in both Prelims and Mains. Therefore, this article not only enhances conceptual clarity but also helps aspirants build analytical perspectives on India’s evolving environmental policies.

Sources:

1. https://www.thehindu.com/news/cities/Delhi/delhi-cloud-seeding-artificial-rain-updates-october-28-2025/article70211599.ece
2. https://www.indiatoday.in/information/story/cloud-seeding-in-delhi-can-artificial-rain-help-reduce-pollution-and-boost-rainfall-2809429-2025-10-28