2012 年 27 巻 1 号 p. 34-40
Cloud condensation nuclei (CCN) activity of aerosol particles is important in determining the cloud formation processes, their properties, and their fate. In particular, organic material (OM) occupies a significant portion of aerosol particles, while their CCN activity is still difficult to predict. This review focuses on CCN activity of OM. A theoretical background is provided based on the Köhler theory. CCN activities of pure compounds are summarized to provide a detail comparison with the theory and experiments, including the limitations in the current experimental procedures. It is discussed how recent advances in laboratory experiments improved our understanding on CCN activity of secondary OM. Observations are always necessary to understand atmospheric aerosol particles. CCN activity of OM derived from observations is also discussed. Finally, open questions for future research are provided.