What does the effective plume height H represent in Gaussian plume modeling?

What does the effective plume height H represent in Gaussian plume modeling?

• A. The height of the atmospheric boundary layer.
• B. The vertical rise of the plume due to buoyancy and momentum (H = h + Δh).
• C. The geometric height of the stack.
• D. The height at which mean mixing occurs.

Answer: (B)

In Gaussian plume modeling, the effective plume height is where the plume’s centerline effectively sits after it rises as it exits the stack. It combines the actual stack height with a rise caused by the plume’s buoyancy and its exit momentum, written as H = h + Δh. This matters because the vertical position used in the dispersion equations determines how the plume dilutes as it spreads downwind, especially the peak ground-level concentrations. The rise Δh grows when the plume is buoyant or exits the stack with high velocity, and it can vary with atmospheric stability and wind speed, so a hotter, faster jet climbs higher before it begins lateral spreading. If the plume rises more, the effective height where dilution starts is higher, shifting concentration patterns downwind. This differs from simply the geometric stack height, which ignores how the plume actually lifts after leaving the stack, and it isn’t the height of the atmospheric boundary layer or a generic “mean mixing height.”

In Gaussian plume modeling, the effective plume height is where the plume’s centerline effectively sits after it rises as it exits the stack. It combines the actual stack height with a rise caused by the plume’s buoyancy and its exit momentum, written as H = h + Δh. This matters because the vertical position used in the dispersion equations determines how the plume dilutes as it spreads downwind, especially the peak ground-level concentrations.

The rise Δh grows when the plume is buoyant or exits the stack with high velocity, and it can vary with atmospheric stability and wind speed, so a hotter, faster jet climbs higher before it begins lateral spreading. If the plume rises more, the effective height where dilution starts is higher, shifting concentration patterns downwind.

This differs from simply the geometric stack height, which ignores how the plume actually lifts after leaving the stack, and it isn’t the height of the atmospheric boundary layer or a generic “mean mixing height.”