Chemical composition and droplet size distribution of cloud at the summit of Mount Tai, China

A significant increase in cloud water acidity at Mount Taishan, China, was observed between 2014 and previous studies (2007–2008), with pH levels rising from 3.86 to 5.87. This shift was attributed to higher nitrate and ammonium concentrations, particularly the overcompensation of ammonium, which neutralized acidity. The study also revealed that cloud droplets at Mount Taishan were predominantly smaller than 26.0 µm, with most ranging between 6.0–9.0 µm, peaking at 7.0 µm. High liquid water content (LWC) broadened droplet size distribution and facilitated the formation of larger droplets. Additionally, higher PM2.5 levels correlated with increased soluble ion concentrations, smaller droplet sizes, and greater droplet numbers, suggesting a strong interaction between cloud droplets and atmospheric aerosols. The research highlights clouds as an important sink for soluble atmospheric materials and emphasizes the need to consider the dilution effect when estimating cloud-phase component concentrations.

Li, J., Wang, X., Chen, J., Zhu, C., Li, W., Li, C., Liu, L., Xu, C., Wen, L., Xue, L., Wang, W., Ding, A., & Herrmann, H. (2017). Chemical composition and droplet size distribution of cloud at the summit of Mount Tai, China. Atmospheric Chemistry and Physics, 17(16), 9885–9896. https://doi.org/10.5194/acp-17-9885-2017