Saharan dust, convective lofting, aerosol enhancement zones, and potential impacts on ice nucleation in the tropical upper troposphere.

Dry aerosol size distributions and scattering coefficients were measured on 10 flights in 32 clear-air regions adjacent to tropical storm anvils over the eastern Atlantic Ocean. Aerosol properties in these regions were compared with those from background air in the upper troposphere at least 40 km from clouds. Median values for aerosol scattering coefficient and particle number concentration >0.

Clarifying the dominant sources and mechanisms of cirrus cloud formation.

Formation of cirrus clouds depends on the availability of ice nuclei to begin condensation of atmospheric water vapor. Although it is known that only a small fraction of atmospheric aerosols are efficient ice nuclei, the critical ingredients that make those aerosols so effective have not been established. We have determined in situ the composition of the residual particles within cirrus crystals after the ice was sublimated.

Predicting global atmospheric ice nuclei distributions and their impacts on climate.

Knowledge of cloud and precipitation formation processes remains incomplete, yet global precipitation is predominantly produced by clouds containing the ice phase. Ice first forms in clouds warmer than -36 degrees C on particles termed ice nuclei. We combine observations from field studies over a 14-year period, from a variety of locations around the globe, to show that the concentrations of ice nuclei active in mixed-phase cloud conditions can be related to temperature and the number concentrations of particles larger than 0.

Mixing of atmospheric gas concentrations.

Atmospheric gas concentrations were measured at 1 s intervals in the upper troposphere during a flight through and near the anvil of a storm. The observed very high correlations between the concentrations of CO and CH4 are interpreted as arising from the mixing of two distinct air masses with differing concentrations of each species, and is due to the nearly identical diffusivities of CO and CH4 in air. We find that the correlations depend on the period over which each concentration measurement was made.

Recovery and sporicidal resistance of various B. subtilis spore preparations on porcelain penicylinders compared with results from AOAC test methods.

Sporicidal test results obtained from carriers inoculated with 4 types of defined Bacillus subtilis spore preparations were compared with the standard AOAC sporicidal test using soil extract nutrient broth (SENB) B. subtilis 19659 spores. Recoveries of spores inoculated on penicylinders from B.