Based on precipitation observation information and NCEP reanalysis data during 1981-2018, the causes of abnormal precipitation in spring sowing period in northern Hubei Province were analyzed by using synthetic diagnostics and atmospheric energy spectrum methods. The results show that in abnormally less precipitation years, the subtropical high was weaker and its position was southerly, and the polar vortex was weaker too. The perturbation kinetic energy over mid-latitude was weak in meridional direction, while the zonal transfer position was southerly, and the angular momentum transferred obviously to the south, the energy exchange between north and south was weak. Thus the intersection of cold and warm air was not obvious over the north of Hubei, and it was divergent in the lower troposphere, which was not conducive to the frontogenesis. In abnormally more precipitation years, both the subtropical high and polar vortex were stronger, the plateau trough was more actively. The perturbation kinetic energy over mid-latitude was stronger in meridional direction, while the zonal transfer position was northerly，the angular momentum transferred obviously and the energy exchanged frequently between the south and north. Thus the intersection of cold and warm air was obvious over the north of Hubei, it was convergence in the lower troposphere, which was conducive to the frontogenesis.

Based on the monthly precipitation observation data at 21 weather stations in North China, global reanalysis data from NCEP/NCAR and circulation indexes data from National Climate Center of China from 1955 to 2014, the variation tendency, mutation and periodic characteristics of cyclonic wind shear frequency in low level in North China were analyzed by using the trend analysis, Mann-Kendall test and wavelet analysis methods, and the influence factors of cyclonic wind shear were preliminary discussed. Results show that the frequency of low-level cyclonic wind shear in North China decreased significantly during 1955-2014, the mutation of cyclonic wind shear frequency appeared in 1967, and there was quasi-3-year period oscillation during 1955-1965 and 1992-2000, while the 4-year period oscillation was significant during 1980-1992. The mutation and periods characteristics of low level cyclonic wind shear frequency were basically coincide with the precipitation in the same periods in North China. The turning change of low-level cyclonic wind shear was obvious in North China, which was mainly caused by the more significant adjustment of atmospheric circulation in the previous year.

Based on conventional observation data，NCEP reanalysis data，satellite images and radar mosaic products，and combined with WRF mesoscale simulation，the severe convective weather which occurred in the south of Shanxi on 22 May，2013 was analyzed． The results show that during this weather process，lasting transport of positive vorticity advection over Hetao area played a significant role in formation，maintenance and development of the cut － off vortex on 500 hPa level． Both the low － level cold advection from the front and more stronger warm advection from the back made the vortex develop continually，and excited isolated cloud clusters nearby． The vertical structure with high － level divergence and low － level convergence above the cloud clusters made the upward motion strengthen continuously． Consequently，the isolated cloud clusters maintained and developed． These meso － and meso － scale clusters were the direct cause leading to this severe convective weather． The dry frontogenesis caused by surface continuous strengthening of water vapor from the sea at the back of high pressure system and the invading of dry air at the front of ridge，was an important triggering mechanism of the strong convective weather． From the radar mosaic products of composite reflectivity，this process resulted from the development and merging of convective cells． The evolution of these cells went through a process from convective cell，merging，ribbon echo，bow echo to weakening and vanishing ，and the whole process was divided into two stages，when the area，intensity and moving speed of echoes were different，the characteristics of convective weather were different too． Obvious differences among three types during this process existed in temperature and humidity profiles and environmental parameters，which could be served as judging the severe convective weathers．

As a major driving factor of environment change，characteristic analysis of climate change is very important for environment detection． In this paper，by taking the Ejin delta in the lower reaches of the Heihe River as the research area，on the basis of temperature and precipitation data during 1960 － 2012 from Ejin meteorological station，the characteristic of climate change over the past 53 years was analyzed firstly by using the methods of Mann － Kendall test，regression analysis and accumulative anomaly，and then Mann － Kendall test and R/S analysis were used to predict the future climate change trend． The results were as followed:The temperature in the Ejin delta increased and precipitation appeared non － remarkable trend over the past 53 years． There were remarkable differences in different decades， the temperature increased most from the 1980s to the 1990s，while precipitation appeared fluctuating change with less － more － less． A dryer and warmer climate trend would be obvious in the 21st century，and the warm winter phenomenon would be significant． Combining the data of GIMMS － NDVI，the East Juyan Lake area and runoff at the Zhengyi gauge station，through the Pearson correlation analysis， we concluded that warm and dry climate trend and the runoff reduction of the Heihe River led to shrink and salinization of the West and East Juyan Lakes，and the vegetation degradation． While the increase of the East Juyan Lake area from 2003 was the result of ecological conveyance water project in 2002，rather than the warming － wetting trend of climate．