This report describes the experimental results obtained by the Risø team during the URAHFREP field trials. Understanding dispersion of industrial Releases of Anhydrous Hydrogen Fluoride and the associated Risk to the Environment and People. The purposeof the field trials was to study the possible influence of HF thermodynamics on the dispersion of atmospheric HF clouds. In order to test if the lift-off or enhanced mixing created by the HF release was strong enough compared to the naturally fluctuationsthe HF releases were accompanied by passive smoke release, made shortly after to obtain a reference to the HF release. The instrumentation included various types of HF sensors, thermocouple arrays, a fully instrumented release rig, a passive smokemachine, a meteorological mast and a lidar backscatter system. This report deals exclusively with the meteorological data and the lidar data. The trials cover a range meteorological conditions. These include neutral conditions with relatively highwindspeed and low humidity as well as unstable conditions with low windspeed and high humidity, the most favorable conditions for lift-off to occur. The lidar was used to scan vertical cross-plume slices 100 meter downwind of the source. A comparison ofplume characteristics for HF clouds and passive smoke clouds has been made. The analysis shows no sign of any difference between the dispersion of HF and passive smoke except for one release, where a positive buoyancy effect cannot be excluded. Anenhanced mixing effect of HF was not observed.