Drop size distribution (DSD) is an essential property for characterizing precipitation processes that can sometimes lead to more intense rainfall in different climate regions. In previous studies, remote sensing instruments like vertically pointing radars and/or wind profilers obtained a stationary distribution with a breakup signature. However, these observations do not explain how the underlying microphysical processes in convective clouds that generate more rain occur or how environmental conditions affect these processes. This study, with its novel approach, aims to statistically investigate DSD��s characteristics within convective clouds using data from a ground-based optical disdrometer and a C-band polarimetric weather radar in eastern Japan. Convective clouds were extracted using a cell-tracking algorithm and operational C-band polarimetric weather radar data, and their environmental conditions were characterized by using upper-air sounding data. The signals of coalescence and accretion are likely to occur at 2?4 km height within the convective clouds, while the signals of breakup and autoconversion are likely to occur below 2 km height. These microphysical characteristics are found to be related to environmental parameters. Specifically, larger drop sizes are associated with higher instability, while a higher number concentration is linked to higher water vapor conditions. These factors influence the precipitation intensity regarding the DSD parameters when a DSD approaches a stationary distribution on the ground. The findings of this study indicate that the DSD approaching a stationary distribution can be identified even from the DSD parameters retrieved from the C-band polarimetric radar variables, and provide valuable insights for predicting and understanding intense rainfall events.