Abstract: I will present the Met Office’s operational dispersion model, NAME (Numerical Atmospheric-dispersion Modelling Environment), a hybrid Eulerian-Lagrangian model which is used operationally for a wide range of applications ranging from emergency response to routine forecasting. I will give an overview of the mathematical and physical basis of the model, describe its functionality and list some of its most widely used applications. The latter includes the transport of pollutants, viruses, Saharan dust and volcanic ash. I will focus on the latter and discuss some of the issues surrounding the modelling of buoyant sources in NAME. If time allows I will present some more theoretical work on the dispersion of pairs in turbulence which is related to the concentration variance.