New Particle Formation in the Atmosphere: From Molecular Clusters to Global Climate

TLDR

New particle formation initiates cloud condensation nuclei and influences health, air quality, weather, and climate, yet fundamental chemical mechanisms and impacts of SO₂, NOₓ, and organic compounds remain poorly understood. The review aims to chart the history of NPF, synthesize recent progress, and identify future research directions, including developing instruments for 3–20 nm particle composition and improving parameterizations across diverse atmospheric conditions. The authors review the literature, summarizing historical developments, recent advances, and outlining challenges and future research directions in NPF. Recent advances include sub‑nanometer instrumentation, laboratory studies of multicomponent nucleation (e.g., CERN’s CLOUD chamber), global observations of NPF across diverse environments, and refined theories and parameterizations for atmospheric models.

Abstract

Abstract New particle formation (NPF) represents the first step in the complex processes leading to formation of cloud condensation nuclei. Newly formed nanoparticles affect human health, air quality, weather, and climate. This review provides a brief history, synthesizes recent significant progresses, and outlines the challenges and future directions for research relevant to NPF. New developments include the emergence of state‐of‐the‐art instruments that measure prenucleation clusters and newly nucleated nanoparticles down to about 1 nm; systematic laboratory studies of multicomponent nucleation systems, including collaborative experiments conducted in the Cosmics Leaving Outdoor Droplets chamber at CERN; observations of NPF in different types of forests, extremely polluted urban locations, coastal sites, polar regions, and high‐elevation sites; and improved nucleation theories and parameterizations to account for NPF in atmospheric models. The challenges include the lack of understanding of the fundamental chemical mechanisms responsible for aerosol nucleation and growth under diverse environments, the effects of SO 2 and NO x on NPF, and the contribution of anthropogenic organic compounds to NPF. It is also critical to develop instruments that can detect chemical composition of particles from 3 to 20 nm and improve parameterizations to represent NPF over a wide range of atmospheric conditions of chemical precursor, temperature, and humidity.