A pure rotational Raman (PRR) lidar based on a second-harmonic generation Nd:YAG laser is built for measuring the atmospheric temperature at altitudes of 5-30 km. A double-grating polychromator is designed to extract the wanted PRR signals and suppress the elastically backscattered light. Measured examples present the overall lidar performance. For the 1-h integrated lidar temperature profiles, the 1σ statistical uncertainty is less than 0.5 K up to ∼17 km, while it does not exceed 2 K at altitudes of 17-26.3 km. Based on 38 nights of high-quality lidar temperature data, the temperature variability is studied. It is found that the variability differs between the nights with inversion layer and those without it. On the nights without inversion layer, the local hour-to-hour temperature variability was mostly less than 1 K at altitudes of 5-17 km. At altitudes of 17-23 km, it grew to 1.2-2.4 K. On the nights with inversion layer, in the middle and upper troposphere, the significant variability was found to occur only at the inversion-layer altitudes. At other tropospheric altitudes off the inversion layer, the variability was generally less than 1 K. The statistical results indicate that the temperature variability mostly was stronger in the presence of inversion layer than in its absence.