That human beings are influencing the climate is a fact: the existence of climate change is a debate that has largely been overcome in the scientific community and more and more research indicates that Anthropocene action is influencing the future of the planet. Now, a new study published in the journal ‘Science‘ corroborates a hypothesis that was suspected but, until now, had not been corroborated: air pollution caused by factories influences clouds and, specifically, could favor local snowfall.
Clouds have a particular physics: although we are taught in school that water freezes at zero degrees, in these formations above our heads water can remain liquid down to -40 degrees. This phenomenon is known as supercooled droplets contained in cold clouds (which are above 0ºC). It has been known for decades that anthropogenic aerosols, derived from industrial activities, the burning of fossil fuels or agriculture, cause a greater number of droplets in clouds.
This new study carried out by researchers at the University of Tartu (Estonia) also demonstrates that the pollution created specifically by factories influences clouds by converting their liquid water droplets into ice at temperatures below zero degrees, which can resulting in snowfall in the regions close to these infrastructures. This conclusion was drawn thanks to satellite images taken of the clouds near these factories. Specifically, in 67 aerosol-emitting industrial sites, such as metal and cement factories, paper factories and power plants, spread across North America, Europe and Asia.
In the images you can clearly see columns of clouds that follow the path that the smoke from the factory could follow, spreading. “In addition, ground precipitation radar data revealed plumes of snow in the same areas where reduced cloud cover was observed in satellite images. “Combining satellite and ground-based radar observations, researchers tracked physical processes from ice formation to snow and reduced cloud cover downwind of industrial hot spots,” the authors note.
Observations of reduced cloud and snow cover downwind of industrial air pollution hotspots
The study suggests that industries such as metallurgical and cement factories, coal-fired power plants and oil refineries emit aerosol particles that cause supercooled liquid clouds to freeze, leading to snowfall.
Other conditions
However, the authors note that aerosols may not be the only substances that impact clouds. Heat and water vapor emitted by industries can also play a role in freezing these cold clouds.
Furthermore, they indicate that this newly discovered reaction only triggers local phenomena and that, at the moment, it has not been possible to demonstrate that anthropogenic aerosols cause this type of snowfall on larger spatial scales. “More research is needed to understand the ability of different types of anthropogenic aerosols to initiate ice formation,” the researchers note.
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