The CLOUD-DOC Marie Curie Doctoral Training Network is a multi-site network of 12 Ph.D. students at 12 partner institutions across Europe. The network investigates various aspects of the interactions of cosmic rays with aerosols and clouds, which bears on the possibility of a "solar indirect" contribution to climate change. Besides the individual research of the Ph.D. students at their hosting institutions, the major focus of the network will be sets of common experiments on ion-induced nucleation and ion-aerosol interaction carried out at CERN. These experiments are conducted at an aerosol chamber that is exposed to a CERN elementary particle beam where the effects of cosmic rays on aerosol and cloud formation can be efficiently simulated.