The shear of basic flow in low latitudes is obvious, among which vertical shear plays an important role The effects of vertical shear on the low\|frequency waves and the interaction between different modes are demonstrated, and it is shown that there is selection in the effects on different mode

Based on the NCEP/NCAR 40-year reanalysis dataset, analysed is the relationship between vertical shear of zonal wind in equatorial lower stratosphere and ENSO variability.

The NCEP/NCAR and JTWC(Joint Typhoon Warning Center) reanalysis data are used to investigate the trends of the frequency,distribution and oscillation periods of maximum wind speed and environmental-wind vertical shear of tropical cyclones over the Northwestern Pacific from May to October,1974 to 2004.

And the liquid water content index of atmosphere,lower horizontal helicity,vertical wind shear of v-component,the difference between 0 ℃ layer altitude atmosphere pressure and 570 hPa,the difference between-20 ℃ layer altitude atmosphere pressure and 370 hPa show important significance for the prediction of occurrence,development and region of severe convective weather.

The results show that the squall line occurred under an unstable stratification,in which it was dry and cold at the upper level,wet and warm at the lower troposphere;its triggering mechanisms include the upper-troposphere jet,ground shear,vertical wind shear,and dry air intrusion in the middle troposphere;its energy sources include the weak ABL water vapor transportation and energy accumulation.

The strong vertical wind shear, low level jetstream and low level confluence is beneficial for the heavy rain development.

It is shows that there is a medium-intensity vertical wind shear and a weak echo area in the hailstorm.

Results show that∶strong vertical wind shear,higher K index,and plentiful water vapor transportation in local area,boundary layer jetstream and instability atmospheric stratification are favorable for the heavy rain.