This paper reports a kind of vertical wind disturbances which appear daily in the afternoon of mid-summer in the troposphere. A detailed analysis was made of wind data monitored by the MU radar (35 ¿N, 136 ¿E, Shigaraki, Shiga, Japan) for about five days in July 1987 as a typical example. The disturbances propagate upward up to (sometimes over) the tropopause level with a speed of 0.4--1.8 m s-1 as a packet. The timing of generation and propagation suggests that they are convective motions of cumulus clouds generated by solar heating on the ground. A map of cloud-top height with high horizontal resolution of about 1 km provided by a satellite of NOAA-9 supports this inference. The structures near the tropopause and spectral characteristics are shown. ¿ American Geophysical Union 1992