## 4 Discussion  
The analysis shown above indicates that millimeter radar is a powerful tool with which to study the fine structure of orographic clouds and precipitation because of its high temporal and spatial resolution. In this case, the vertically pointing K-band MRR presented the temporal evolution of precipitation and the differences in rain microphysics during different precipitation segments well. The Ka-band cloud radar also showed the fine structures of clouds in an ambient condition with vertical wind shear well. The measurements clearly indicated that the cloud formation and evolution were strongly controlled by the vertical wind shear based on the reflectivity and radial velocity. A combination of millimeter radar measurements and high-resolution simulation effectively revealed the role of vertical wind shear in the process of cloud development, including the inhibitive impact of the vertical wind shear on the development of convective cells and the formation of multi-layer clouds. However, one limitation of millimeter radar measurement is its relatively small detection range; thus, the results shown in this paper are only relevant for the clouds in the sample area. It can be seen from the satellite measurement (Figure 2a) and model simulation (Figure 10a) that the clouds covered the entire area of the Tian Shan Mountains in this case and the spatial variability was large, suggesting that the clouds that formed at different locations had different characteristics. Therefore, clouds formed outside of the radar detection range might interact with vertical wind shear differently. For example, Figure 14  
Figure 13: Modeled cross-section of (**a**) the tendency of convective stability, (**b**) the vertical wind shear term, and (**c**) the divergence term of the convective stability tendency at 9:00 UTC along the east black line in Figure 10. S and N below each panel indicate south and north of the cloud radar; (**d–f**) and (**g–i**) are the same as (**a–c**) but for 10:00 and 11:00 UTC, respectively. shows the thermodynamic conditions along the west black line shown in Figure 10, where a deeper level of convection occurred. The vertical wind shear at \(\sim\)4 km was weak, and the convergence induced between the southerly and northerly flow was strong (Figure 14a). As the vertical wind shear was balanced by the upslope wind, continuous convection could be triggered. Thus, the convection was as deep as 9 km and the vertical velocity was nearly 15 m s\({}^{-1}\). The tendency of convective stability (Figure 14b) was influenced by both the vertical wind shear and divergence in similar magnitudes, and both of them had a negative impact on the stability below 4 km (Figure 14c,d). The divergence was strong above 9 km due to the stable atmosphere (Figure 14a,d), preventing the upward development of convection. A previous study conducted using the WRF model also indicated that deep convective clouds may form over the Tian Shan Mountains despite the presence of strong vertical wind shear [10]. The impact of vertical wind shear on cloud development over the Tian Shan Mountains could be more complicated than that over a plain. Firstly, the convective precipitation had a diurnal variation over the Tian Shan Mountains. [PERSON] et al. [36] showed that during summer, the peak precipitation rate was found over the mountain ridge in the late afternoon and moved northward as time went on. Therefore, the heights of the vertical wind shear level relative to the convection initiated near the surface may vary diurnally. For wind shear close to the surface, an inhibiting impact on the convection initiation could be expected if the shear was strong enough, while if the shear was well above the surface, convective clouds could develop to a higher level, thus interacting with vertical wind shear in a different way. Additionally, the vertical wind shear was often influenced by gravity waves induced by the Tian Shan Mountains. An example of this is the lee wave of the southerly cross-ridge flow.