New particle formation in the free troposphere: A question of chemistry and timing

TLDR

Many tropospheric particles form in situ, but the fraction and precise mechanisms remain uncertain. The study combined laboratory, field, and modeling work to show neutral nucleation exceeds ion‑induced nucleation by more than tenfold, with size‑dependent growth rates and a limited time window for new particle formation. High‑altitude observations revealed that roughly half of tropospheric particles are newly formed by condensation of highly oxygenated multifunctional compounds. Bianchi et al.

Abstract

From neutral to new Many of the particles in the troposphere are formed in situ, but what fraction of all tropospheric particles do they constitute and how exactly are they made? Bianchi et al. report results from a high-altitude research station. Roughly half of the particles were newly formed by the condensation of highly oxygenated multifunctional compounds. A combination of laboratory results, field measurements, and model calculations revealed that neutral nucleation is more than 10 times faster than ion-induced nucleation, that particle growth rates are size-dependent, and that new particle formation occurs during a limited time window. Science , this issue p. 1109