The weakest convective instability is at the occluded stages of cyclone 气旋锢囚期对流不稳定最弱。
In the violent stages of development of cyclone , the convective instability becomes weak greatly 在气旋强烈发展期对流不稳定大大减弱。
The north of the low - layer of rain belt was mainly convection instability . so the northern inertia - gravity wave was not easy to develop and to spread 雨区的北部低层以对流不稳定为主，因此向北的重力惯性波不易发展传播。
In a word , convective instability strong baxoclinicity barotropic advection of potential vorticity and latent heat release are factors which activize this explosive development of cyclone 总之，对流不稳定、强斜压性和正压位涡平流、潜热释放是本次气旋发展的启动因子。
At the same time , the disturbance of the low - level jet might be the triggering condition for heavy rain . but the surface occluded front crossing qinling mountains and strengthening , maybe the direct reason 同时，由于冷空气是从中层侵入西北地区东部，这样就形成了较强的对流不稳定层结，有利于对流降水的发生。
So we found that convection instability could inspire inertia - gravity wave . symmetry instability was benefited for spread of inertia - gravity wave and further influenced the development and motion of precipitation 可见对流不稳定可激发重力惯性波，对称不稳定可使重力惯性波发展与传播，从而影响到降水的发展与活动。
By the analysis of the relationship among convective instability , symmetric instability and snowstorm , we found that the convective instability level is under 800hpa . snow belt is located in the negative value region of moist potential vorticity and verified the theory of symmetric instability 最后分析了这场暴雪中西北和东北地区的对流和对称稳定度，个例分析表明，暴雪产生在低层对流不稳定的情况下。
It is the important mechanism that middle - level dry and cold air current sunk , low - level warm and wet air current ascended . level direction energy sharp section is important to blaze middle scale hypo - circumfluence . severe convection weather was brought by layer - knot latent instability 上层干冷、下层暖湿的位势不稳定层结可以使对流层中低层出现明显的逆温层，有利于不稳定能量积累，此次天气过程产生的对流不稳定能量大，形成的上升气流深厚。
We analyzed the meso - scale disturbance field and found that the development and spread of inertia - gravity wave had a close relationship with the development and spread of the rain belt . at the initial stages of precipitation , convection instability was strong in the low level above rain region . convection instability could inspire inertia - gravity wave 对中尺度扰动场分析发现重力惯性波的发展和传播与雨带的发展与传播有密切的联系：在降水初期，雨区上空低层的对流不稳定较强，对流不稳定可激发出重力惯性波。
The result indicates that , in the course of the rainstorm in huoshan , there are obvious low - level jet of great intensity , infection of mesoscale shear line , enhancement of plus vorticity which increases intensity of convergence , improves ascending velocity and brings on precipitation , and quick enhancement of helicity which provides the basis to forecast , in addition , convergence of moisture flux and analyzed potential vorticity which reflects baroclinic convective instability sufficiently indicate the characteristics of the rainstorm 结果表明：此次霍山暴雨发生前后，存在明显的大强度低空急流，并受到中尺度切变线的影响，而且正涡度的加强引起了辐合加剧，提高了上升速度从而引起降水，同时暴雨发生前螺旋度的迅速增强，也为预报提供了根据，另外水汽通量的辐合以及分析位涡反映出的斜压对流不稳定都充分体现了这次降水的特点。
