Since August 2002, temperature measurements from 1 to 105 km are performed at the Leibniz Institute of Atmospheric Physics in K¿hlungsborn (54¿N) with a combination of different lidars. Results from 14 nights in winter and 31 in summer are presented. Nightly mean profiles and fluctuations with a temporal and vertical resolution of 15 min and 1 km, respectively, are derived. In both seasons, wave energy propagates upward (phase propagates downward) with vertical phase speeds of -0.25 to -1.9 m/s. Phase speeds are generally larger in the mesosphere compared to the stratosphere because of decreasing static stability. Wave periods are found in the entire range of 1--8 hours (given by experimental constraints) with no preference for particular periods. The observed vertical wavelengths cover the entire instrumental range of 5--50 km, but the majority lies below 22 km in both seasons. In single nights, a few waves (up to three) dominate the wave spectrum and represent 45--65% of the entire variability. Wave amplitudes generally increase with altitude with a scale height of ~18--22 km, i.e., less than expected (14 km) for propagation conserving momentum flux density. The gravity wave energy loss changes with altitude and is different in both seasons. Local fluctuation minima ("nodes") are often observed, frequently colocated with convective instabilities. Temperature fluctuations are generally smaller in summer compared to winter (maximum values are 10 and 25 K, respectively). Applying gravity wave polarization relations to the mean winter and summer lidar temperature profiles, the difference of fluctuations is basically determined by the background conditions, especially at ~60--80 km.