By Scientists have sussed out a new source for the seeds of clouds. When the stratospheric layer of Earth’s atmosphere dips a toe into the underlying troposphere, the resulting chemical mixture becomes a fertile environment where tiny new particles, including the microscopic aerosols around which clouds begin to coalesce, can form.
The data were collected by two NASA campaigns, each including multiple airborne measurements, in different regions of the northern hemisphere in 2016, 2017 and 2018. These data confirmed that this mechanism, called stratospheric air intrusion, is not only a source of new particles but also may be the most productive place for these particles on Earth, Jiaoshi Zhang, an aerosol scientist at Washington University in St. Louis, and colleagues report in the July 12 Science.
