Study shows industrial aerosols can cause local snowfall by freezing clouds

Research led by the University of Tartu has revealed a possible link between industrial air pollution and local snowfall. Observations using both satellite and ground-based radar indicate that industrial facilities in North America, Europe, and Asia may trigger local snowfall due to ice formation in supercooled clouds. This phenomenon, observed near factories such as copper smelters and coal power plants, results from the release of aerosol particles that interact with clouds under specific atmospheric conditions. Dr. V. Toll, Associate Professor at the University of Tartu, highlighted the importance of interdisciplinary research in identifying this process.

Aerosol and ice formation

Industries, especially those involved in cement production, metallurgy and fossil fuel combustion, emit aerosols – tiny solid and liquid particles that significantly affect cloud properties. It has been observed that aerosols increase the number of cloud droplets, causing clouds to brighten and reducing solar radiation reaching the Earth’s surface. However, new findings show that, under some conditions, these particles also cause liquid cloud droplets to freeze, resulting in snowfall from industrial sites. Weather radar images taken near industrial sites in Canada and Russia show unique piles of snowfall, a finding confirmed by satellite data that indicate a concurrent reduction in cloud cover.

supercooling in cloud droplets

Cloud droplets can remain in liquid form at temperatures as low as -40 degrees Celsius, in a process called supercooling. Only when suitable particles, such as anthropogenic aerosols, are present, can these droplets freeze at temperatures between zero and -40 °C. Toll’s team suggests that aerosol emissions, combined with heat and water vapor from industrial facilities, are driving the formation of ice within the clouds, resulting in snowfall. Although this phenomenon has been observed at specific sites, it is uncertain whether similar mechanisms affect cloud formation on a larger scale.

Further research is needed

The study, published in Science, emphasizes the need for further investigation of the role of different aerosol types in ice nucleation processes. Future research will aim to understand whether these localized snowfall events have broader atmospheric effects and to identify the types of aerosol emissions most effective in initiating ice formation in supercooled clouds.