A Mie scattering lidar was operated at Alert, NWT, Canada, for 9 weeks for the winter of 1984/85 in order to determine vertical profiles of Arctic haze. During the study period, the strong sulphate aerosol concentration maximum, representative of previous years, was not found due to a low pressure system which remained in the Baffin Bay for much of the winter. The relatively clean air is believed to be typical of southerly air flow to Alert. The vast majority of lidar profiles, which did not contain scattering from hydrometeors, showed little change in scattering structure with height. Several events of increased light scattering due to aerosols were noted and allowed examination of three possible mechanisms for the vertical movement of haze: motions following potential temperature isentropes, foehn (chinook) development and ice crystal precipitation scavenging. Abstract A Mie scattering lidar was operated at Alert, NWT, Canada, for 9 weeks for the winter of 1984/85 in order to determine vertical profiles of Arctic haze. During the study period, the strong sulphate aerosol concentration maximum, representative of previous years, was not found due to a low pressure system which remained in the Baffin Bay for much of the winter. The relatively clean air is believed to be typical of southerly air flow to Alert. The vast majority of lidar profiles, which did not contain scattering from hydrometeors, showed little change in scattering structure with height. Several events of increased light scattering due to aerosols were noted and allowed examination of three possible mechanisms for the vertical movement of haze: motions following potential temperature isentropes, foehn (chinook) development and ice crystal precipitation scavenging.