Non-precipitating cumulus cloud study

This document describes the field experiment that was conducted in Kentucky during the period from July 20 to August 24, 1983. The objectives were to determine the vertical transport of acidic pollutants by cumulus convection and formation of acidic substances in non-precipitating clouds. The study is a research component of Task Group C (Atmospheric Processes) of the National Acid Precipitation Assessment Program. To examine the vertical transport, an SF/sub 6/ tracer was released from one aircraft, sampled by another aircraft, and sampled on the ground. The results show that pollutants from the boundary layer are lifted to the cloud layer. From there, they are intermittently transported both to the ground and to higher elevations, possibly in the vertical updrafts of towering cumulus clouds. A series of instrumented aircraft flights around the clouds were conducted to study the formation of acidic aerosols. The concentrations of SO/sub 2/, SO/sub 4/, NO/sub 3/, NH/sub 4/, NH/sub 3/, HNO/sub 3/ and trace metals were measured by filter techniques. Furthermore, NO/sub x/, O/sub 3/, light scattering, and basic meteorological parameters were measured in real-time. Detailed chemical composition of aerosols and NH/sub 3/ was also measured on the ground. Preliminary results show that the molar ratio of SO/sub 2//SO/sub 2/ + SO/sub 4/) at cloud tops is higher than at cloud bases. This indicates that sulfate aerosols were formed in the clouds. The NH/sub 3/ concentration shows higher values at nighttime than daytime and decreases sharply with increasing altitude. 3 references

Measured chromium distributions resulting from cooling tower drift

Useful data concerning the distribution of drift from a mechanical draft cooling tower were derived from field measurements despite the non-ideal conditions which were encountered. Observed chromium fluxes ranged from about 1 mg (m/sup 2/hr)/sup -1/ at a distance of 30 m from the tower to about 1% of that value at a kilometer. Air concentrations of chromium were fairly constant at about 50 ng m/sup -3/ to a distance of about 200 m downwind of the tower, apparently due to thorough mixing in the wake of the tower and a lack of lateral dilution of the effiuent from a crosswind line source. A simplified droplet trajectory model appears capable of estimating drift deposition flux within an order of magnitude. Neither that model nor the experimental data are sufficiently detailed to permit definitive assessment of cooling tower drift. The proper assessment of cooling tower drift deposition for general application would require a comprehensive investigation centered on an isolated cooling lower whose operational characteristics are well-defined and subject ulo cont rol. Documentation of the drift droplet spectrum and properties of the buoyant plume and the adjacent atmosphere are essential to such an effont. (auth

Sulphur deposition on the Italian area: a trajectory model study

2nonenoneCALORI G.; FINZI G.Calori, G.; Finzi, Giovann