Small scale structures of NLC observed by lidar at 69°N/69°S and their possible relation to gravity waves

► Temporal and spatial variability of NLC at 69°N and 69°S. ► Typical cloud duration of 5 h corresponds to 720 km horizontal extent. ► Multiple layer occurrence of ∼10% of the time, separated by 1.5-3 km. ► Layer tilt up to 2° on scales of 40 km, but no preferred orientation. ► Layer characteristics at 69 S affected by stratospheric dynamics.