We developed PAPPUS, a trajectory model for wind dispersal of plant diaspores under field conditions. The model considers the effects of topography, turbulence (including thermal updrafts), and different weather conditions on the dispersibility of diaspores by wind. In the model, the plant species are characterized by the initial release height and the falling velocity of their diaspores. The common problems in modeling turbulence, which limit the applicability of existing models in predicting long-distance dispersal, are avoided by measuring the high-frequency fluctuations of the wind vector and using these data to simulate the course of the wind vector in the model. Using PAPPUS, we simulated dispersal distance spectra and compared them with those observed during field experiments executed in open habitats. Within a broad range of landscapes and under different weather conditions, the results of the model represent the observed spectra reasonably well. Additionally, we compared the observed dispersal di...