The Earth’s atmosphere and airborne microorganisms are interlinked in many ways. The atmosphere serves as a major conductor for the dispersal of microbial cells, which has been key for the early colonisation of continents and for the contemporary distribution of microorganisms. Microorganisms can survive stressful conditions in the atmosphere and may be able to maintain active metabolisms while airborne, which expands our understanding of the limits of life. Finally, microorganisms have key impacts on atmospheric processes, in particular the formation, optical properties and lifetime of clouds, by which they may impact the global climate. In this lecture, I will give insights into the ability of microorganisms to enter the atmosphere, survive and maintain their metabolic activity as well as impact atmospheric processes. These insights are based on field studies that we have performed in polar regions and on laboratory simulation studies, where we investigate microbial responses to simulated atmospheric conditions. These findings have implications for defining the limits of life as well as for the search for life on exoplanets.