The Tianshan Mountains (TM), a critical water tower in arid Northwest China, govern regional atmospheric hydrology through concentrated orographic clouds. Yet, systematic characterization of their 3D cloud structures remains limited. Here, by leveraging 12 years of CloudSat/CALIPSO observations (2006–2017), we unveil the spatiotemporal anatomy of TM cloud systems. We report that total cloud frequency peaks over the MTM (55.74%), declining toward both the WTM (53.03%) and ETM (47.12%), with two distinct vertical cloud fraction maxima at 4–7 km and 7–12 km. Ice clouds dominate the phase composition (40.79%). Among cloud types, As is most prevalent (26.35%), followed by Sc and Cu (~12%); Ci accounts for 7.00% overall but increases markedly eastward, reaching 9.96% over the ETM. While westerly uplift sustains vigorous cloud development (Cu, Ns) over the WTM and MTM, progressive moisture depletion downstream suppresses low-cloud formation, thereby shifting cloud regimes toward high-level Ci dominance over the ETM. Seasonally, total cloud frequency peaks in summer (65.46%) with enhanced supercooled water content, contrasting with an autumn minimum (44.17%). Radar reflectivity decays eastward, indicating weakening precipitation intensity and diminishing hydrometeor content. These patterns, primarily governed by orographic modulation of westerly moisture transport, pinpoint optimal windows (May–September) and locales (WTM and MTM) for cloud seeding. Our findings establish the first 3D cloud climatology over the TM, providing a satellite-validated framework for precipitation enhancement and water-cycle management in arid Asia.

CloudSat/CALIPSO satellites; Cloud properties; Tianshan Mountains, Characteristics of horizontal and vertical distribution; Seasonal variations