The Unevenness of Warm‐Season Precipitation Over the Steep Terrain in North China and Its Related Environmental Conditions

ABSTRACT The spatial unevenness of precipitation significantly impacts local hydrological cycles and exacerbates natural hazards. However, the underlying mechanisms governing such variability over complex terrains remain poorly understood. This study bridges this gap by employing a spatial unevenness index to investigate environmental conditions and fine‐scale characteristics of precipitation events with different spatial unevenness over the steep terrains in North China. Results show that strongly uneven precipitation events are associated with unstable atmospheric stratification and high convective available potential energy (CAPE). Both cold‐top–warm‐bottom temperature anomalies and wet‐bottom–dry‐top humidity anomalies enhance atmospheric instability. Under the thermodynamic influence of complex terrain, these events cluster along the mountains and predominantly occur in the afternoon, coinciding with diurnal peaks in both precipitation frequency and intensity. In contrast, weakly uneven precipitation events are mainly driven by synoptic‐scale forcing, featured with lower‐tropospheric convergence, upper‐tropospheric divergence, and strong large‐scale upward motion. Warm anomalies in the upper troposphere and abundant moisture transported by anomalous low‐level southerly winds are crucial to these events. Spatially, weakly uneven precipitation events spread extensively across North China, covering both mountains and plains. Maximum precipitation amount occurs at the foot of mountains, highlighting the blocking and uplifting effects of topography. For this type, precipitation amount and frequency peak in the early morning, whereas intensity peaks in the afternoon. These findings advance our understanding of precipitation unevenness and provide a scientific basis for improving flood forecasting and water resource management in complex terrains.