Kinetic mean-field models for mass aggregation, such as coagulation equations, have so far mostly been studied in their homogeneous version without space dependence. In this project, we plan to investigate inhomogeneous versions of these models with emphasis on physically relevant situations where spatial dependence competes with aggregation and critically changes the structure of solutions. In the first funding period, we plan to study a kinetic model for the onset of rain showers and inhomogeneous versions of the classical Becker-Döring model for phase transitions.