Our idealized atmosphere is described with a constant buoyancy frequency $N_{d}$, a constant surface temperature $T_{0}$, a uniform unidirectional windspeed $U_{0}$, and a constant relative humidity $RH_{0}$. Our results are limited to $N_{d}>0.011s^{-1}$, $RH_{0}=0.95$ and $T_{0}=273K$, so that both conditional and convective instabilities are suppressed.
Based on around 50 runs to steady states, we demonstrate that moist processes, such as diabatic heat release and precipitation can modify mountain flow stagnation. The dynamical, and thermodynamical features of this modification are diagnosed and discussed based on model output and theoretical formulation. It is found that the dynamical structure of moist air flow can be critical to both orographic cloud formation and precipitation. Fundamental issues such as spill-over and rain shadow, flow-over and flow-splitting or blocking, and precipitation efficiency are addressed. Interesting findings include: Windward precipitation increases with mountain height until flow splitting occurs. Further increasing the mountain height may decrease precipitation; Windward precipitation increases with windspeed to a critical value which is determined by mountain width and height and air stratification. For stronger wind, local precipitation may decrease; The precipitation efficiency is influenced by the ratios of different time scales, such as time scales for a parcel drifting across the topography, for growing of snowflakes, and for hydrometers falling, etc.
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