Variations in Fog and Cloud Composition with Droplet Size and Their Influence on Aerosol Processing

EPA Grant Number: U915364
Title: Variations in Fog and Cloud Composition with Droplet Size and Their Influence on Aerosol Processing
Investigators: Moore, Katharine F.
Institution: Colorado State University
EPA Project Officer: Lee, Sonja
Project Period: August 1, 1998 through August 1, 2001
Project Amount: $77,370
RFA: STAR Graduate Fellowships (1998) RFA Text |  Recipients Lists
Research Category: Academic Fellowships , Air Quality and Air Toxics , Fellowship - Atmospheric Sciences


The objective of this research project is to characterize experimentally how fog/cloud formation affects local aerosol properties. The resulting data set should provide information regarding how fog/cloud processing impacts aerosol subject to the PM2.5 and PM10 standards, and be useful for model validation.


A new active cloudwater collector ("the CSU 5-Stage") has been developed to separate collected droplets into more fractions (five), than previously possible (two or three). The CSU 5-Stage has been used successfully in the field—yielding five chemically distinct droplet size fractions over sampling intervals as short as 1 hour. The current understanding of cloud droplet variation mechanisms does not explain all measured chemical concentrations. The CSU 5-Stage collector, operated as part of an integrated field sampling campaign, provides additional detail of spatial variations in cloudwater chemistry to enhance this understanding. Complementary physical and chemical measurements to fully characterize pre- and postcloud aerosol, the cloud itself, selected gas-phase species, and meteorological conditions are made simultaneously. Radiation fogs are particularly useful for isolating cloud effects on aerosol, and will be studied in the San Joaquin Valley and other, similar, locations.

Supplemental Keywords:

fellowship, atmospheric chemistry, fog chemistry, fog composition, radiation fog, cloud, aerosol, cloud processing, cloud composition, droplet size, fog, fog/cloud formation, droplet fractions, particulate matter, PM, PM10, PM2.5., RFA, Scientific Discipline, Air, Geographic Area, particulate matter, Southwest, Applied Math & Statistics, air toxics, Environmental Chemistry, Chemistry, State, Analytical Chemistry, Atmospheric Sciences, Engineering, Chemistry, & Physics, fog composition, atmospheric reactions, aerosol processing, San Joaquin Valley, atmospheric aerosols, aqueous phase atmospheric reactions, cloud composition variations, droplet size, aerosol, California, aerosols, aerosol sulfate

Progress and Final Reports:

  • 1999
  • 2000
  • Final