There are large gaps in the knowledge of the relationship between aerosols and clouds, which makes it the largest uncertainty factor in climate models. Annica Ekman, Department of Meteorology, and Paul Zieger, Department of Environmental Science, have received funding for the project ”Clouds and climate transitioning to post-fossil aerosol regime: CleanCloud” from Horizon Europe. The project aims at substantially increasing the knowledge about the interplay between aerosols and clouds and improving the representation of related processes in climate models.