Credit: Unsplash/CC0 Public Domain How are cold air masses advancing in the United States connected to fertilizers carried by "flying rivers" from Africa that nourish the soils of the Brazilian Amazon? An article published in Geophysical Research Letters reveals an atmospheric connection between these distant regions. Scientists discovered that synoptic systems—large-scale meteorological phenomena spanning thousands of kilometers—such as cold waves in the U.S. and high-pressure anomalies in the South Atlantic, modify heavy rainfall along the tropical belt of the Atlantic Ocean. During the wet seasons, these changes determine whether the Amazon receives air laden with particles from Africa or air free of these aerosols. "Clean" days (with fewer particles) were preceded by peak precipitation in the ocean. Until now, the reason for these fluctuations was unclear, and it was assumed that the influence stemmed from changes in wind direction.…