Scientists bear witness to birth of an ice cloud

Scientists bear witness to birth of an ice cloud Scientists have witnessed the birth of atmospheric ice clouds, creating ice cloud crystals in the laboratory and then taking images of the process through a microscope, essentially documenting the very first steps of cloud formation. The team witnessed a process known as ice nucleation in unprecedented detail, taking time-lapse movies of the first few seconds when a

particle attracts water vapor, forming ice crystals that become the core of icy cirrus clouds—the high, wispy clouds that act much like a blanket for our planet.how clouds form and what they do has a major influence on our climate and is a focus of scientists studying our planet. Clouds can reflect the sun's light, keeping the planet cool, or absorb the Earth's radiation, heating the planet. The latter is the case for ice clouds created under the conditions in this study. The complex chemistry of airborne particles that serve as the birthplace of the ice crystals adds additional challenges. "This is one of the most critical but least understood parts of the process of how cold clouds form," said first author Bingbing Wang, a scientist formerly with EMSL, the Environmental Molecular Sciences Laboratory at the Department of Energy's Pacific Northwest National Laboratory. "The fundamental process of how ice grows is relatively well understood, but ice nucleation—that moment when the first group of molecules comes together—remains a big challenge," said Wang, who is now a professor at Xiamen University in China. To take a close-up look at the initial steps, Alexander Laskin, a leader of the EMSL group, brought together scientists from Stony Brook University, Lawrence Berkeley National Laboratory, and PNNL, as well as the resources of two DOE Office of Science User Facilities: EMSL and the Advanced Light Source, which is at the Berkeley Lab. The team, with Daniel Knopf leading the Stony Brook group and Mary Gilles leading the Berkeley group, describes the work in the Nov. 21 issue of Physical Chemistry Chemical Physics.