The aim of CLACE was to gain insight into the physical and chemical properties of ice nuclei by making measurements of ice and liquid cloud particles, ice nuclei and composition measurements of the residual particles found within these different particle types at a high altitude alpine field station in the Swiss Alps. The CLACE 4 project is one of a series of projects led by the Aerosol Research group of The Paul Scherrer Institute, and is based at the Jungfraujoch High Alpine Research Station in Switzerland. The CLACE-4 project led by the University of Manchester was funded by NERC.