In 1987, dispersion experiments and extensive meteorological measurments were carried out at an overburden tip called ''Sophienhoehe'' near the Research Centre J¿lich. In addition to classical instruments like radiosondes, a tethered ballon, towers, and sonic detection and ranging, free-flying ballons, so-called tetroons, were used. Three tetroons were launched during nighttime and six tetrons during daytime conditions. Measurements from a selected field experiment formed the basis for a simulation of a tetroon flight using the flow over terrain with natural and anthropogenic heat sources (FITNAH) mesoscale model. Our verification study showed that the tetroon trajectory was well simulated. Some differences can be explained by the model results. This case study showed that FITNAH is a model which can simulate stable air flow in a very realistic way, and it further showed that tetroon flights have the potential to be a valuable tool to evaluate flow simulations. It is planned to do similar comparison for the daytime flights. ¿American Geophysical Union 1990