Dispersion in low wind speed conditions is governed by meandering that disperses plumes over wide angular sectors, thus g.l.c. are lower than predicted by Gaussian models. It was proposed to model these dispersion situations in homogeneous conditions with two coupled Langevin equations, based on low wind speed turbulence analysis. Their parameters were derived from the autocorrelation functions of horizontal wind that exhibit an oscillations and large negative lobes. We propose a new equation system for: general case of inhomogeneous turbulence; total velocity; for the windy situations (based on the 'Thomson simplest solution') and verify that these new solutions satisfy the 'well-mixed condition'.
Keywords: LWS, low wind speed, dispersion modelling, Langevin equations, meandering, well-mixed condition, air pollution, pollutant dispersion, air quality, turbulence analysis