Human emissions are creating new cloud-forming particles

Human activity is changing atmospheric chemistryEven in remote locations, that can change how and when clouds form.

“The Storm Peak Laboratory is a remote site in the Intermountain West,” says Gannett Haller, professor of atmospheric sciences. “Just because we only measured that doesn’t mean it’s not happening at all the other remote sites in the Intermountain West.”

For clouds to form, there needs to be something in the air, such as a grain of earth or salt, around which the water vapor begins to condense., These are some particles about one-tenth the diameter of the spider’s silk, which are called “cloud nuclei”.

As you can imagine, clouds play an important role in weather, reflecting solar energy and moving water from one place to another. So being able to realistically model those clouds could help increase the accuracy of the models that forecast changes in our climate.

To understand the connection between the formation of new aerosol particles and cloud condensation nuclei, recent graduate Noah Hirschhorn, Haller and their colleagues delved into a 15-year record of aerosol measurements at the Storm Peak Laboratory, led by the University of Utah. There is a facility. Haller and Steamboat Ski Resort in Colorado have elevations of over 10,500 feet (3,210 m).

“Given the Storm Peak Lab’s remote mountain location,” the authors write, “clear atmospheric conditions are common at the lab.”

Above the lab, however, are several power plants that emit sulfur dioxide, a gas that turns into sulfuric acid in the atmosphere, which can turn into particles and cause new particle formation events.

For about 20 years, the formation of new particles has been measured by people looking at three-dimensional graphs showing measurements of aerosol particles over time. The presence of a burst of new particles as well as some pattern of consistent growth of those particles form criteria for designating new particle formation events.

But Hirschhorn, Haller and other researchers, including U undergraduates Lauren Zuromsky and Christopher Rapp, developed an automated, statistics-based method for classifying new particle formation events. The new method improves the accuracy and efficiency of event detection and agrees well with manual detection methods.

Using this method, Researchers found new particle creation events occurred at Storm Peak on 50% of days between 2006 and 2021, But by comparing rates of new particle formation to the number of particles large enough to serve as cloud condensation nuclei, the authors found that new particle formation events increased by a factor of 1.36 in winter and the number of cloud condensation nuclei Is. 1.54 in the spring.

“Every other day we see gases condensing into nanoparticles that are large enough to absorb water and turn into cloud droplets,” Haller says.

“This provides a clear connection from a new particle formation event to cloud condensation nuclei,” says Hirschhorn. “The biggest direct benefit from this would probably be that climate modelers can connect with each other. It fills a lot of gaps.”

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