Lagrangian Puff Model

A Lagrangian puff model calculates how gas released from a chimney or a leak spreads on the wind by breaking it up not into one long continuous plume, but into a series of small puffs. Picture the smoke from fireworks: instead of drifting away as a single unbroken cloud, it separates into individual puffs that each get carried off by the wind and gradually fade.

What sets this approach apart is that it doesn't run its calculations on a fixed grid. Instead, it follows each puff directly, tracking how its position and concentration change over time. That makes it comparatively good at reproducing short, localized releases even when wind direction and speed keep shifting moment to moment.

This kind of calculation is especially useful for interpreting the hazy gas traces seen in satellite or camera imagery. To tell whether such a shape is really gas that has spread naturally on the wind, or just some unrelated surface feature that happens to look similar, you first need a baseline understanding of how gas disperses in wind.