Understanding Cloud Seeding and Air Pollution Control

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Key takeaways

Cloud seeding uses agents like silver iodide (AgI) and sodium chloride (NaCl) to artificially induce rain from existing clouds.
An IIT Delhi study indicates that pollutant levels often return to pre-rainfall levels within 1 to 5 days due to constant emissions.
The Pusa Decomposer by ICAR provides a biotech solution to stop crop burning by turning stubble into manure in 15-20 days.
Cloud seeding requires specific conditions, including 15-20% humidity in target clouds and the presence of Western Disturbances in North India.

Delhi and the National Capital Region (NCR) are facing dangerous Air Quality Index (AQI) levels after Diwali in November 2026.
To handle this emergency, authorities have proposed using Cloud Seeding (Artificial Rain) to clean the air.
Many people doubt if this will work because trials in October 2025 produced very little rain and did not improve air quality for long.

Cloud seeding is a technology used to change the weather. It forces or increases rain by adding certain chemicals, called seeding agents, into existing clouds.
The main goal is to speed up the natural rain process. This helps in managing droughts, fighting heavy air pollution, or stopping hail.
There are two main types of seeding. Glaciogenic Seeding uses agents like silver iodide (AgI) to create ice crystals in cold clouds, which leads to snow or rain.
The second type is Hygroscopic Seeding. It uses particles like sodium chloride (NaCl) in warm clouds to help water droplets grow and fall as rain.

In nature, water vapor clings to cloud condensation nuclei (CCN) like dust, smoke, or sea salt to form tiny droplets.
These droplets grow by collecting more vapor or by bumping into other droplets. Once they get heavy enough, they fall as rain.
In cold clouds, vapor can turn directly into ice crystals. These either fall as snow or melt into rain as they descend.
During cloud seeding, chemicals are spread using drones, aircraft, or ground generators. These chemicals act as artificial CCN or ice nuclei.
These artificial agents provide a strong base for water vapor to freeze or condense quickly. This speeds up the process and creates artificial rain or snow.

Artificial rain creates a washout effect. As the rain falls, the droplets catch and pull down pollutants like PM2.5, PM10, soot, and toxic aerosols.
This process physically removes the pollution from the air and deposits it on the ground. As a result, the AQI and visibility improve quickly, though only for a short time.

Cloud seeding cannot create rain from a clear sky. It only works if there are already clouds present.
The clouds must be deep enough and have enough moisture. Usually, the targeted cloud layer needs 15-20% humidity.
In North India during winter, this process depends on Western Disturbances. These are storms from the Mediterranean that bring the needed moisture and clouds.

It only provides short-term relief. An IIT Delhi study showed that pollutant levels often return to normal within 1 to 5 days because emissions continue.
The study also suggested that ground-level ozone might actually increase after the rain.
Success depends on unpredictable weather. Winter clouds over Delhi are often too thin or dry to produce much rain, even with seeding.
The cost is very high. Using specialized planes and pyrotechnic flares costs crores of rupees for a small area.
There are ecological risks. Using silver iodide for a long time can leave heavy metals in the soil and water, harming fish and crops.
It can lead to rain theft. Changing weather in one area might stop rain from falling in nearby regions that are already struggling with drought.
It has a carbon footprint. Flying planes and using dry ice (carbon dioxide) adds to greenhouse gas emissions.

The United Arab Emirates (UAE) has flown about 1,000 hours of seeding flights every year since the 1990s to increase groundwater and desert rain.
Australia uses this technology in the Snowy Mountains and Tasmania to boost hydropower and water supplies.
In the United States, states like Texas, Colorado, and California use it to increase snow in mountains for irrigation and reservoirs.
China runs one of the largest programs in the world. They use drones, planes, and artillery to fight droughts and stop hail.

The CSIR-NEERI developed the Wind Augmentation Purifying Unit (WAYU). These are placed at busy traffic lights to remove pollutants using filters and UV systems.
Smog Towers use huge filters, including HEPA or electrostatic filters, to pull in dirty air from the top and release clean air at the bottom.
Smog-eating paints use Titanium Dioxide (TiO2). When sunlight hits the paint, it breaks down toxic Nitrogen Oxides (NOx) into harmless salts.
Anti-smog guns spray tiny water droplets (50-100 microns) at high speeds. This settles dust and PM particles at construction and mining sites.
The ICAR developed the Pusa Decomposer. This is a liquid made of fungi that turns paddy stubble into manure in 15-20 days, so farmers do not need to burn it.
Smart traffic management using AI and IoT can stop cars from idling at red lights. This reduces NOx and Carbon Monoxide at junctions.
Urban greening through the Miyawaki method creates dense forests that act as natural filters for dust.
In-situ management uses machines like Happy Seeders and Super SMS to manage crop waste in Punjab, Haryana, and UP without burning.
Moving to Electric Vehicles (EVs) and better public transport helps reduce tailpipe emissions.