(a) Use the wind speed and direction from the time of puff creation to determine that puff's movement. Note that to be consistent with the derivation of the Gaussian puff model, we assume that wind speed and direction are constant during each puff's lifetime but can vary from one puff to the next. This assumption is reasonable in practice, as each puff persists for only a few seconds to minutes on a typical oil and gas production site and new puffs are created frequently.