Work out plume dispersion estimate instantly with clear inputs, formula shown and shareable results.
The Gaussian plume model gives ground level concentration as Q / (pi u sigma_y sigma_z) times an exponential term for the stack height. Dispersion coefficients grow with distance and depend on atmospheric stability — the values here approximate neutral Pasquill class D conditions.
Gaussian plume
C = Q / (pi u sigma_y sigma_z) x exp(-H^2 / (2 sigma_z^2))
Dispersion modelling for regulatory purposes requires approved models, site-specific meteorology and terrain data. This is a screening estimate only.
Very stable conditions produce high concentrations far downwind, while unstable conditions can cause short-lived high ground level values from looping plumes. Screening must test a range of classes.
Physical height plus plume rise from buoyancy and momentum, which can add tens of metres for a hot high-velocity plume. It is the height that actually governs dispersion.