Analyze the natural causes of drought in Yunnan in winter and spring?
Winter and spring are seasonal drought periods in Yunnan, with scarce natural precipitation and large evaporation, which is prone to meteorological drought. According to experts' analysis, due to the special topographical conditions and the distinct climatic characteristics of dry and wet seasons, the regional distribution of precipitation in Yunnan is quite different and uneven during the year, which leads to the occurrence of drought in Yunnan with obvious regional and inter-annual characteristics.
Regionally, Lijiang, Dali, Chuxiong, Kunming, Zhaotong, Qujing, Honghe and Wenshan are often drought-prone areas, especially in the dry-hot valley areas along the north of Dali, Chuxiong, Dongchuan and Jinsha River, with the highest drought frequency and the most serious drought phenomenon. From the seasonal point of view, the inter-seasonal long-term persistent drought has the greatest impact, especially in winter and spring, which has the most serious impact on agricultural production, with the frequency of 65%, followed by summer drought with the frequency of 28%.
In addition, cold air has been located in the northeast since the middle and late of 65438 10, and the middle and low latitudes in East Asia are mainly controlled by relatively gentle westerly airflow, which is not conducive to the transportation of warm and humid airflow, resulting in continuous sunny and hot weather and rapid development of drought in our province. Experts explained that Yunnan is located in the famous Asian monsoon climate zone, and summer is mainly affected by the southwest monsoon. Because the southwest monsoon carries a lot of water vapor from the ocean, there is more precipitation in Yunnan and the climate is humid in summer.
In winter, Yunnan is mainly affected by the easterly airflow in the continental high-pressure front or the westerly airflow passing through the south side of the Qinghai-Tibet Plateau, which is relatively dry, with scarce precipitation and dry climate. Since the beginning of winter, the temperature in most parts of Yunnan is basically normal, and the precipitation is slightly less. The long-term sunny and hot weather has caused the meteorological drought in most parts of our province to develop rapidly from the beginning of February.