Formation of new aerosol particles in the atmosphere and its impact on climate

Aerosol particles in the atmosphere are important because of their impact on climate. One of these effects relates to the fact that cloud droplets form on aerosol particles (so-called cloud condensation nuclei, CCN), and that an enhanced number concentration of CCN results in an increased reflection of the formed clouds, exerting a cooling on our planet. About 50% of the particles are not directly emitted as particles but are formed in the atmosphere from gaseous precursors. According to the Svensmark hypothesis this process is most influenced by the Sun’s interaction with galactic cosmic rays and therefore the latter is responsible for the major part of today’s warming. This presentation will give insight into the CLOUD experiment at CERN, which was set up to test the Svensmark hypothesis.