It comes to the conclusion that the strong clear air turbulence is caused by the energy transition of the baroclinic atmosphere,the activity of northwest jet and the momentum downward transfer.

So this kind of storm was called NE jet storm.

Based on a new climate variability theory “Energy complement each other and balance between westerly jet in winter and subtropical high in summer ”presented by the author in this paper, the flood and drought prediction in China from 1997 to 2001 had been completed.

The significant impact of heating fields on the upper-tropospheric westerly jet has been revealed in much previous research,but little effort has been paid on differentiating the relative contribution of various heating fields over tropical and subtropical regions.

In this paper, westerly jet, storm track and baroclinic wave packets of upper troposphere in the Northern Hemisphere at summer of 1980?1998 are analyzed by using NCEP/NC.

Due to the dynamic effect of the cold air in the north and the thermal effect caused by the southwest jet, the temperature of surface raised, the humidity enhanced and the gradient piled up, then the developed convection lead to downward momen.

In this study,the monthly wind and temperature fields from ECMWF(European Center for Medium-Range Weather Forecasts) reanalysis dataset ERA40 are used to investigate the characteristics and variabilities of the East Asian-western Pacific westerly jet stream(WJS) in winter seasons.