Which of these factors does NOT influence dispersion modeling according to the Pasquill-Gifford model?

The Pasquill-Gifford model identifies several critical factors that influence the dispersion of pollutants in the atmosphere, including wind direction, release height, and atmospheric stability. The model's design focuses primarily on how pollutants disperse due to environmental conditions rather than the ambient pressure surrounding the release point.

Wind direction is crucial as it determines the path that pollutants may take after they are released. Understanding this direction is fundamental for predicting where contaminants may settle or drift. Release height plays a significant role as well; pollutants released from different heights will disperse differently due to variations in atmospheric layering and turbulent mixing.

Stability class refers to the atmospheric conditions that dictate how pollutants mix with ambient air. It accounts for temperature inversions and other thermal structures that can prevent or enhance mixing, significantly affecting how far and in what manner pollutants will disperse.

In contrast, atmospheric pressure, while a fundamental meteorological parameter, does not directly impact dispersion modeling in the context of the Pasquill-Gifford model. This model's primary concern is with how specific meteorological and physical parameters influence dispersion rather than with pressure variations, which are relatively static and do not significantly alter the diffusion processes described by the model.