Atmospheric Aerosols: Some Highlights and Highlighters, 1950 to 2018

The science of atmospheric aerosols began more than a century ago; it has experienced major advancements after the mid-twentieth century with motivation from diverse public interests and concerns for environmental protection. At least six generations of mentored investigators have involvement in these advancements. Since the 1950s, important knowledge has emerged in the theory of the dynamics of suspended particles and advanced measurements. Important developments in the theory of atmospheric aerosols include: (a) nucleation and growth mechanisms, (b) formalization of particle dynamics in the Knudsen regimes, (c) characterization of the mechanisms for the particle-size distribution, (d) identification of chemical processes for atmospheric particle sources, and (e) model integration of particle physical and chemical processes with meteorological processes. Important advances in measurements have included: (a) semicontinuous determination of particle-size distributions, (b) new methods for sampling and analysis of mass concentration and composition, (c) methods for continuous characterization of aerosol chemical properties, and (d) development of direct sensing techniques using optical properties. Examples of breakthroughs in these areas are given in the text. Illustrations of achievements in each of the areas are included in the paper. The survey is completed with comments on the generational nature of investigator contributions to aerosol science.