The sensitive Doppler radar (49.92 MHz) at Jicamarca (12.0°S, 76.9°W) is used to investigate short-period atmospheric waves at the altitudes of 13–25 km. The dominant short-period waves observed are largely buoyancy, or Brunt-Väisälä, oscillations, the periods of which are about 5 min in the lower stratosphere and about 11 min in the upper troposphere. The buoyancy oscillations are, on the average, convected with the mean horizontal wind. It is also confirmed that the partial reflection is relatively dominant in these altitudes compared with turbulent scatter. These features are not found around the tropopause, where a vertical shear of horizontal winds of the order of 5 m s−1 km−1 is observed.