## 3 Results
### Characteristics of the Atmospheric Stability Indices  
Since the atmospheric stability indices mentioned in Section 2.2 are related to the characteristics of parcel heights, representative height indices such as the convective condensation level (\(CCL\)), lifting condensation level (\(LCL\)), level of free convection (\(LFC\)), and equilibrium level (\(EL\)) are presented here first. Among them, \(CCL\) refers to the height of an air mass heated sufficiently near the ground and then adiabatically uplifted until condensation. \(CCL\) is generally produced from surface heating and thermal convection, which is often used to identify the cumulus layer. \(LCL\) refers to the height when a dry adiabatic air mass is lifted to humidity saturation. \(LCL\) is often used to identify the cloud bottom caused by terrain and windward systems. \(LCL\) value is generally less than or equal to \(CCL\). \(LFC\) indicates the height of the turning point of the difference between the gas temperature and the ambient temperature from negative to positive. \(LFC\) represents the height when the difference between parcel temperature and ambient temperature changes from negative to positive in the process of gas mass lifting. Then, as the air parcel becomes hotter than the surrounding air, the air parcel continues to rise to the point at which the temperature again becomes equal to the ambient temperature, which is called \(EL\). The \(EL\) value is generally used to estimate the tops of convective clouds, especially thunderstorms. Figure 6 shows the statistical characteristics of the parcel height (from 8:00 to 20:00 monsoon season) under different weather conditions. The \(CCL\) values were higher on snowy days after 11:30 and higher on sunny days before 11:30. The average \(CCL\) values (and corresponding \(RMS\)s) were 513.29 hPa (15.05 hPa) and 543.17 hPa (14.01 hPa), respectively. The minimum value of \(CCL\) appeared at approximately 15:30 (UTC+8), which indicated that the overall cloud height continuously increased during the period of 8:00-16:00 (UTC+8). For \(LCL\) and \(LFC\), a similar trend was observed except for the sampling time at approximately 17:50 (UTC+8). That is, from 08:00 (UTC+8) to 20:00 (UTC+8), both the \(LCL\) and \(LFC\) values decreased to the valley value (approximately 15:00, UTC+8) and generally increased to their maxima. This can be attributed to the daytime solar radiation and heating effect. The average \(LCL\) value of the sunny environment was almost consistent with the \(LFC\) value: 513.29 hPa and 515.38 hPa, respectively. For snowy days, the average value of \(LCL\) was 23.86 hPa greater than that of \(CCL\) because the surface temperature had not yet risen to a critical value, that is, the convective temperature, before the air parcel began to rise vertically due to positive buoyancy. The average \(LFC\) on snow was 50 hPa larger than that on sunny days, indicating that there exists a positive correlation between the probability of precipitation events and \(LFC\). The \(LFC\) value given in Figure 6 (d) denotes the height difference between \(EL\) and \(LFC\). There was little difference in \(LFCEL\) between sunny and snowy days, with averages of 236.62 hPa and 244.19 hPa during the daytime. However, there was obviously a difference between the rainy and sunny \(EL\) over the QTP during the summer monsoon [31]. In summer, the \(EL\) values on sunny and cloudy days were almost the same, less than those on rainy days. In Figure 7, the statistical characteristics of four different stability indices, _CAPE_, _DCAPE_, _CIN_, and _MVV_, under different weather conditions during the EAWM, are presented. During the EAWM of the QTP, the _CAPE_, _DACPE_ and _MVV_ showed a trend of first increasing and then decreasing, and the corresponding moments of peak were 14:00, 15:30 and 13:30, respectively. The _CAPE_ values under snowy conditions were larger than those on clear days, especially during the period of 13:00-19:00 (UTC+8).