Cosmic rays, aerosols, clouds, and climate: Recent findings from the CLOUD experiment

The Cosmics Leaving OUtdoor Droplets (CLOUD) experiment was created to systematically test the link between galactic cosmic rays (GCR) and climate, specifically, the connection of ions from GCR to aerosol nucleation and cloud condensation nuclei (CCN), the particles on which cloud droplets form. The CLOUD experiment subsequently unlocked many of the mysteries of nucleation and growth in our atmosphere, and it has improved our understanding of human influences on climate. Their most recent publication (Gordon et al., 2017) provides their first estimate of the GCR-CCN connection, and they show that CCN respond too weakly to changes in GCR to yield a significant influence on clouds and climate.