Journal Article

Cloud Activation Characteristics of AirborneErwinia carotovoraCells

DeMott, Paul J., Franc, Gary D.

1998

Overview

Several strains of plant pathogenic bacteria,Erwinia carotovora carotovoraandE. carotovora atroseptica, were observed to be active as cloud condensation nuclei (CCN). The CCN supersaturation spectra of bacterial aerosols were measured in the laboratory and compared to the activity of ammonium sulfate. Approximately 25%–30% of the aerosolized bacterial cells activated droplets at 1% water supersaturation compared to 80% activation of the ammonium sulfate aerosol. Physical and numerical simulations of cloud droplet activation and growth on bacteria were also performed. Both simulations predict that aerosolized bacteria will be incorporated into cloud droplets during cloud formation. Results strongly support the hypothesis that significant numbers of the tested bacterial strains are actively involved in atmospheric cloud formation and precipitation processes following natural aerosolization and vertical transport to cloud levels.

• Publisher: American Meteorological Society
• Subject: Aerosols / Bacteria / Clouds / Crystals / Precipitation / Quaternary ammonium compounds / Scavenging / Snow / Sulfates / Supersaturation