[en] In the Upper Rhine Valley near the Karlsruhe Nuclear Research Center 19 tetroons were tracked by radar during the years 1978, 1980 and 1982. The mean flight levels of the tetroons varied between 300 m and 1000 m, the maximum range of tracking extended up to 83 km. Some of the tetroons had been equipped with transponders. During the measuring campaigns additional meteorological data were supplied by the 200 m high meteorological tower erected on the site of the Nuclear Research Center, by a Doppler sodar and by radiosondes. The measured values received from the radar are used to calculate the trajectories of the tetroons. They are represented as profiles and in horizontal projections. The measured trajectories are compared with calculated ones. The latter have been derived from various models and a number of meteorological data measured at fixed locations. The trajectories are the basis for calculating horizontal dispersion parameters which are compared with results of own tracer experiments. (orig.)