Frank Stratmann

TL;DR: First results from the CLOUD experiment at CERN are presented, finding that atmospherically relevant ammonia mixing ratios of 100 parts per trillion by volume, or less, increase the nucleation rate of sulphuric acid particles more than 100–1,000-fold and ion-induced binary nucleation of H2SO4–H2O can occur in the mid-troposphere but is negligible in the boundary layer.

TL;DR: Measurements of new particles observed immediately after their formation at atmospherically relevant sulfuric acid concentrations suggest that freshly formed particles contain one to two sulfuric Acid molecules, a number consistent with assumptions that are based on atmospheric observations.

TL;DR: It is shown, in experiments performed with the CLOUD (Cosmics Leaving Outdoor Droplets) chamber at CERN, that sulfuric acid and oxidized organic vapors at atmospheric concentrations reproduce particle nucleation rates observed in the lower atmosphere.

TL;DR: It is suggested that this new atmospherically relevant oxidation route is important relative to oxidation by the hydroxyl radical, at least at moderate concentrations of that radical.

TL;DR: Investigating the formation of extremely low volatility organic compounds (ELVOC) from O3 and OH radical oxidation of several monoterpenes and isoprene in a series of laboratory experiments shows that biogenic SOA formation in general, and ELVOC in particular, play crucial roles in atmospheric CCN production.