Radon detectors at Bern and Jungfraujoch were used to monitor the transport of radon-rich boundary layer air from the Swiss Plateau to the Alpine ridge. Radon was successfully used to discriminate between different types of vertical transport, using the shape of the diurnal cycle to identify days with upslope mountain winds. For many air-mass properties, however, the total land-surface influence (indicated by the radon concentration) was more decisive than the type of vertical transport.