Liusong dynasty belongs to the(old period of historical(limate evolution on the whole } but there was a fluctuation of temperature during this period the temperature was relatively low during the early years and during the middle and later periods of Yuanjia,it rose to the highest and dropped to the lowest in the period of Taishi} but in the end of Liusong dynasty the temperature rose again This kind of fluctuation presented through various kinds of(limatic; description is also reflected by the characteristicof floods and droughts at that time.  Generally speaking incold period . the time occurging floods in a year is later than that in warm period.  The time and precipitation of Meiyu were controlled by the fluc;tuation} and it would influence the(ondition of floods and droughts this is the(onc;entrated expression of temperature fluctuation