Based on the IPCC report, 1 aerosol-cloud interactions are still the largest uncertainty in our understanding of our global climate. By aerosol photo-chemical properties and their ability to act as precursors for cloud condensation, these atmospheric particles play an important role. Approximately half the number of cloud droplets are anticipated to be formed from newly formed aerosols. Hence, understanding the new particle formation (NPF) process of aerosol particles is crucial. NPF is thought to occur via the formation of atmospheric molecular clusters that potentially grow to larger sizes unless they are lost via coagulation with larger particles. A molecular cluster can be viewed as an aggregate of not-covalently bound molecules and as an intermediate between isolated molecules and a bulk system. The physicochemical properties of clusters are size-dependent and differ from bulk systems containing the same substances. By definition, micro-scale aerosol particles can, to a large extent, be considered bulk systems, as the portion of surface molecules compared to the whole cluster becomes negligible with the increasing cluster size. The transition between clusters and bulk systems