At a Glance

A 15-year international study found that modern coal-fired power plants can alter rainfall patterns.For years, it was assumed exhaust from road traffic was the primary source of ultrafine particles.This long-term study proves otherwise.

Modern coal-fired power plants produce more ultrafine dust particles than road traffic and have the ability to alter rainfall patterns, a new 15-year study says.

According to the paper published this week in the Bulletin of the American Meteorological Society, filtration systems on modern coal plants are the (UFP). These tiny particles can impact "rainfall distribution on local to regional scales by increasing the condensation nuclei count."

For years, it was assumed exhaust from road traffic was the primary source of UFPs, but this new research suggests that's not entirely true.

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Because more countries are commissioning these modern plants with this type of filtering system, UFP concentrations are continuously rising.

To conduct their research, Professor Wolfgang Junkermann from the Karlsruhe Institute of Technology (KIT) in Germany and Professor Jorg Hacker from Airborne Research Australia built two research aircraft that resemble flying tricycles.

These flying laboratories enabled the researchers to fly near and downwind from power stations in dozens of countries and take of dust particles, trace gases, temperature, humidity, wind and energy balances, according to a press release.

Using these aircraft, which are touted as the smallest flying laboratories on Earth, the researchers could trace the UFPs back to the original source – the power plants.

"Our two research aircraft are particularly suitable to follow the plumes from the smokestacks downwind for hundreds of kilometers and study their behavior in great detail," said Hacker.

After collecting measurements, the researchers compared the data with meteorological observations.

"We found that fossil power stations have for many years become the strongest individual sources of ultrafine particles worldwide," Hacker said. "They massively influence meteorological processes and may cause extreme weather events, including intensive rain events. By redistributing rainfall events, this can lead to drier than usual conditions in some places and to unusually heavy and persistent strong rainfall elsewhere."

The paper said UFPs that influence clouds and precipitation are as little as 100 nanometers in diameter and have an enormous impact on environmental processes. For perspective, a sheet of paper is 100,000 nanometers thick.

Particles that originate from wildfires, dust storms, volcanic eruptions and nature itself are not in the nanometer range, so they don't fall under the UFP category.