The first rainy season in South China is a unique climate phenomenon. It is hypothesized that the
particular topographic characteristics (e.g. mesocale mountains) give rise to such a phenomenon. 10
years' Tropical Rainfall Measuring Mission (TRMM) precipitation radar (PR) data such as rainfall
frequency and vertical profile regarding two different kinds of rainfalls (i.e. stratiform and convective
rainfall) are comparatively considered. It is discovered that terrains play an important role in the
determination of the occurrence and intensity of rainfall, even these almost neglected mesoscale
mountains. The above is also confirmed by 6 years' Atmospheric Infrared Sounder (AIRS) temperature
and humidity data.