The HYSPLIT model is tool that explains how, when and where potentially harmful materials are atmospherically transported, dispersed & deposited. This understanding is essentially important in responding and preventing disaster. The expansion: Hybrid Single-Particle Lagrangian Integrated Trajectory
The HYSPLIT model is a complete system for computing simple air parcel trajectories to complex dispersion and deposition simulations.
The dispersion of a pollutant is calculated by assuming either puff or particle dispersion. In the puff model, puffs expand until they exceed the size of the meteorological grid cell (either horizontally or vertically) and then split into several new puffs, each with it's share of the pollutant mass. In the particle model, a fixed number of particles are advected about the model domain by the mean wind field and spread by a turbulent component. The model's default configuration assumes a 3-dimensional particle distribution (horizontal and vertical).