Cloud seeding: trials begin in Delhi

In India's federal capital – which has topped the list of the world's most polluted cities for over ten years – the first silver iodide rockets have been launched with the aim of causing artificial rain. The Centre for Atmospheric Sciences is sceptical, calling it an ‘improper application of science’ for political propaganda purposes.

Milan (AsiaNews/Agencies) - The Delhi regional government has launched a cloud seeding experiment to induce artificial rainfall, in the hope of reducing the levels of pollution that for years have made the air in the Indian capital among the most unbreathable in the world.

The initiative, promoted by the ruling Bharatiya Janata Party (BJP), aims to verify whether the intervention can help mitigate the environmental emergency that suffocates the city, especially in the winter months. The process involves dispersing silver iodide particles into the clouds using aeroplanes or drones. These particles act as nuclei around which water droplets aggregate, increasing the likelihood of precipitation.

After months of delays due to unstable weather, the first experimental flight took place at the end of October, a few days after air quality had plummeted to “dangerous” levels following the Diwali celebrations, the festival of lights. Delhi's Environment Minister, Manjinder Singh Sirsa, confirmed that silver iodide rockets had been launched and that, weather permitting, the city could see its first artificial rain.

However, experts remain sceptical. The technique only works in the presence of dense clouds, sufficient humidity and favourable currents: conditions that are rarely present above Delhi, which is characterised by dry air and low humidity in the winter months. Similar experiments in other Indian states, such as Tamil Nadu and Karnataka, to stimulate rain in drought-stricken areas have produced mixed results. Even abroad, countries such as China, Thailand and the United Arab Emirates have only been successful when the timing and weather conditions were ideal.

Several scholars at the Centre for Atmospheric Sciences in Delhi have called the project a “political gimmick”, comparing it to the anti-smog towers installed in the past that proved ineffective. In an editorial published in The Hindu newspaper, the researchers denounced “the misuse of science and the absence of ethics”, also warning of the potential environmental and health risks associated with the repeated use of chemicals such as silver iodide or sodium chloride.

The opposition, led by the Congress Party, called the measure a ‘cruel joke’, arguing that any temporary improvements in air quality in limited areas would not justify the high costs of the operation. According to the World Meteorological Organisation (WMO), research into artificial climate modification is still in an experimental phase. This was also reiterated by M. Ravichandran, secretary of the Ministry of Earth Sciences, during a conference on the subject in Pune. Ravichandran explained that the tests in Delhi, conducted in collaboration with the Kanpur Institute of Technology, ‘were purely experimental’ and that only through such tests can we understand if and how the technology can be applied on a larger scale. “Every experiment,” he added, “can have positive or negative outcomes, but both provide useful data for future research”.

Delhi, which has ranked first among the most polluted cities on the planet for over ten years, recorded a 6% increase in smog levels in 2024, due to a combination of agricultural combustion, industrial emissions and heavy traffic. In the cold months, concentrations of fine particulate matter (PM2.5 and PM10) far exceed those recorded during Beijing's 2013 “airpocalypse”. While artificial rain promises to be a quick but uncertain solution, many experts insist that only structural interventions, such as reducing emissions, controlling agricultural burning and more sustainable mobility, can restore breathable air to Delhi.