A practical puff model based on the Monin-Obukhov similarity theory is
presented. The model uses approximate solutions for the dispersion of
a cloud of passive contaminant released from instantaneous sources an
d where particular importance is given in describing the interaction b
etween wind shear and vertical diffusion. The model performances are e
valuated against tracer ground-level concentrations released near the
ground and at a height of 115 m.