"The aim of the proposed Marie Curie Initial Training Network is to establish a multi-site network of early stage researchers (ESRs, here predominantly PhD students) at 9 partner institiutions across Europe to investigate 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 ESRs at their hosting institutions, the major focus of the network will be two sets of common experiments on ion-induced nucleation and ion-aerosol interaction carried out at CERN to which all ESRs contribute. 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. A comprehensive training programme is set up for the network participants. Additional to the experiments at CERN, the trainees are brought together by several network training events such as annual summer schools and workshops. Here, courses and lectures by world leading experts are taught spanning from ""aerosol chemistry and physics"" in general to specialized sessions on subjects such as ""ion-induced aerosol nucleation"" or ""influences of galactic cosmic rays on paleo-climate"". The summer schools and workshops are scheduled in addition to the national PhD programmes of their hosting institutions where a variety of courses is available to the ESRs . The summer schools will include training on complementary skills such as ""writing scientific publications"", ""preparing and presenting talks and seminars"", ""interaction with media"", ""commercializing scientific results"". A multitude of secondments are proposed in which individual ESRs visit other institutions of the network to conduct specific research tasks there that will broaden their research experience and skills."