When we talk about natural processes—especially atmospheric—nothing is too small to be irrelevant. Recently, researchers in Brazil and the United States found that nanoparticles of pollution play an outsize role in cloud formation and disruption, altering rain cycles even in pristine forest areas.
The study, published in Science Advances, showed that human-made aerosols smaller than 10 nanometers, previously thought to be too tiny to act as cloud condensation nuclei or have any influence on climate processes, can become climatically active as they swell on their way to the upper layers of Earth’s atmosphere.
The team used a Gulfstream 1 research airplane from the U.S. Department of Energy to fly about 5 kilometers above Manaus, Brazil, an urban patch of 2 million residents surrounded by the Amazon rain forest, on 13 and 17 March 2014. The plan was to find out how aerosol-cloud interactions played out not only over urban areas but also over relatively unperturbed forest regions.
—Name, Science Writer