Abstract: By using the Ningxia summer torrential rain days data, the Yinchuan sounding data and the NCEP/NCAR reanalyzed data, the evolutional characteristics and the cause of Ningxia torrential rain days are analyzed under the background of climate warming. The results show that both annual torrential rain days and annual mean temperature displayed a consistent trend, which means that with increase in annual mean temperature, the annual torrential rain days also increased obviously. Further analysis results indicate that atmospheric potential instability has been grown in the daytime in both July and August after the climate warming (1986) of Ningxia, but in the nighttime it has been grown in July but decayed in August. Therefore, the climate warming not only caused more obvious diurnal variation of the vertical distribution of atmospheric temperature in Yinchuan, but also resulted in the increase of torrential rain days and in more obvious diurnal variation of the torrential rain in Ningxia.

Key words: climate change, torrential rain days, atmospheric circulation, formation mechanism, Ningxia