Acidity Workshop at the US Environmental Protection Agency in North Carolina, USA during May 2019 leading to the publication by Pye et al. (2020). Pictured (left to right): Jeff Collett, Maria Kanakidou, John Walker, Havala Pye, Nicole Riemer, Andrew Ault, Athanasios Nenes, Simon Clegg, Rahul Zaveri, Andreas Tilgner, Mary Barth, Jim Kelly, Faye McNeill, and Andreas Zuend. Coauthors not pictured: Becky Alexander, Kathleen Fahey, Christopher Hennigan, Harmut Herrmann, I-Ting Ku, Thomas Schaefer, Guoliang Shi, Tao Wang, Rodney Weber, Jia Xing. Photo courtesy EPA and A. Nenes.
Many of us learned about acidity, or pH, in high school chemistry. We learned that acids like HCl could dissociate into H+ and Cl- and the activity of those H+ ions defined the acidity. In the atmosphere, the same basic definition of acidity, or pH on the molality scale, applies to aqueous phases like suspended particles and cloud droplets. Atmospheric acidity regulates what kinetic reactions are ...[Read More]