Feats of formation

Aerosols – a suspension of small solid and liquid particles in the air – directly affect the Earth’s energy budget by scattering and absorbing solar radiation, and indirectly by acting as cloud condensation nuclei (CCN) that infl uence cloud properties and precipitation. The aerosol indirect radiative forcing (IRF) – largely determined by CCN concentrations – is a major source of uncertainty in interpreting climate change over the past century and projecting future change. Recent studies show that tropospheric CCN abundance and aerosol IRF are sensitive to the particle formation and growth processes. In order to gain high fi delity predictions of current and future climate, particle formation and growth have to be adequately understood and properly represented in the climate models.