Ammonia vapor was released into the atmosphere with the objective of measuring downwind concentrations in the plume. Three ammonia vapor source characteristics-- elevation, concentration, and velocity--were experimentally varied to investigate their influence on the downwind concentration. The tested ammonia source characteristics were as follows: elevations 2.0 m (6.5 ft) and 8.1 m (26.5 ft), concentrations 100% and 1% by volume, and vertical velocities 10 m/s (32.8 ft/s) and 50 m/s (164 ft/s). Ammonia vapor detectors were placed at 24 m (80 ft), 48 m (160 ft), and 96 m (320 ft) downwind at elevations of 2.0 m (6.5 ft) and 8.1 m (26.5 ft). The database obtained consists of 81 releases. The data indicate that ground-level ammonia vapor concentrations are reduced with the experimental increases in elevation, concentration, and upward velocity by factors of 0.2, 0.5, and 0.8, respectively. The experimental data are compared to predictions from a plume dispersion model.

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