Abstract: The "thermal forcing" of the two-step terrain from the Tibetan Plateau to the Loess plateau can be treated as a monsoon effect derived from an "amplified sea-land temperature difference", which has an unpredictable effect on the dynamic "driving" of changes in regional and even global atmospheric circulation systems. The Qingzang plateau is featured by the highest concentration of low cloud cover and the most active convective activity in Asia. This special turbulence-convection triggering mechanism provides a key energy driving source for the cloud water resources of the "Asian Water Tower". The unique "thermal forcing" and "two-step water pump" effects of the Qingzang plateau provide a dynamic mechanism for strong "convergence" of water vapor flows from low-latitude oceans and even across hemispheres. During active monsoons, the "large triangular sector", a key influence area of water vapor transport and some other areas in the low-latitude tropical ocean are important water vapor source areas for the atmospheric water cycle of the "Asian water tower", and the source areas can be traced across the equator to the southern Hemisphere. In summer, the cross-equatorial airflow in the southern and northern hemispheres is characterized by lower-level southerly flow and upper-level northerly flow. They occur in the equatorial region corresponding to two major terrains, respectively: East Asia (90°E) and North America (90°W). The extreme value areas of these two cross-equatorial reversed airflows coincide with the positions of the Qingzang plateau in Asia and the Rocky Mountains in North America, respectively. From the perspective of planetary-scale circulation characteristics, it also confirms that the topographic features of the Qingzang plateau and the Rocky mountains at different heights are responsible for the formation of the vertical-latitudinal and vertical-meridional circulations across the hemispheres. The study reveals the crucial "window effect" of the Qingzang plateau in global energy and water vapor transport, manifesting the key role of thermal forcing in the energy and water cycle processes of the Qingzang plateau, namely the "Asian water tower". Significant correlation of convective activities over the Qingzang plateau with global stratospheric water vapor transport in the Antarctic and Arctic is identified, highlighting the linkage of the "three poles". The coupling mechanism of high-level divergence and low-level convergence driven by the heat source over the Qingzang plateau leads to a strong "convergence" effect of multi-scale water vapor transport over long distances on the Qingzang plateau, forming the thermal forcing and the "self-triggered feedback" effect of energy and water cycle on the Qingzang plateau. The glaciers, snow, and lakes scattered on the "Roof of the World" store abundant water resources, which can to some extent serve as a "water tower storage pool". The Qingzang plateau maintains an important feedback loop with global atmospheric energy and water cycle processes. This land-ocean-cryosphere atmospheric energy and water exchange mechanism can depict a systematic image of multi-layer water cycle between the Qingzang plateau and the Earth's atmosphere.