Lei Sun and other researchers took cloud samples from an area of high elevation in Southern China to examine the chemical characteristics. In total, 141 cloud samples were collected during 44 cloud events over the observation period. (Sun 2015) The primary acidifying factors were sulfate and nitrate, like the many other tests for acid rain though there were some neutralizing elements like calcium and ammonium. They also detected many other very dangerous chemicals in high concentrations in these samples like Pb, Ba, As, and Cr –lead, barium, arsenic, and chromium respectively. The overall pH level came out around 3.79. The variation in cloud chemistry indicated that temperature, sandstorms, and long-range transport could affect the concentrations of species and the lives of many people. (Sun 2015) The data collection method used in this study would have been detached observation of the rainwater and various cloud samples taken from the area of study. Then the researchers needed to compare those findings with measurements taken in other regions of China and east Asia in general. This group studied southern China because it has been identified as the third largest region to be experiencing acid rain pollution after Europe and North America. The research question for this topic was how the chemicals effect the make up of clouds and why acidic clouds behave differently from a more neutral one.

Sun, Lei, et al. “Evaluation of the Behavior of Clouds in a Region of SevereAcid Rain Pollution in Southern China: Species, Complexes, and Variations.” Environmental Science and Pollution Research 22.18 (2015): 14280-14290.