The relationships among cloud microphysics, chemistry, and precipitation rate in cold mountain clouds

A study was conducted to examine the relationships among air pollutant load ings, cloud microphysics, and snowfall rates in cold mountain clouds. It wa s hypothesized that variations in pollutant loadings would be reflected in shifts in the cloud droplet size distribution. A field program was conducte d at Storm Peak Laboratory (SPL) at an elevation of 3210 m MSL in northwest ern Colorado. Cold precipitating clouds were sampled during January, 1995. Cloud water was collected and analyzed for major ion and trace element chem istry. Cloud droplet concentrations and size were measured continuously usi ng a PMS FSSP-100. The results indicate a direct relationship between clear -air equivalent (CAE) sulfate concentrations in cloud water and cloud dropl et concentrations, an indirect relationship between droplet number and drop let size, a direct relationship between droplet size and snowfall rate, and an indirect relationship between CAE sulfate concentration and snowfall ra te. (C) 2000 Elsevier Science Ltd. All rights reserved.