Causes of the Plum Rainy Weather Syndrome

We all know that plum rain syndrome often occurs in the southern Guangxi area. Plum rain weather is a typical weather in southern my country. Plum rain weather often causes rainy weather for a long period of time. So what exactly is plum rain weather syndrome? Let us now learn about the plum rain weather syndrome!

Causes:

The study found that the Eurasian continent between 20N and 40N is a zone alternately controlled by the subtropical high pressure and the westerly belt. On the west coast of the continent, in summer, the weather is clear and cloudless, and the climate is hot and dry, under the influence of the subtropical southerly pressure east of the sinking airflow. In winter, under the influence of the westerly belt, warm and humid air is brought from the Atlantic Ocean, resulting in more precipitation, making the climate mild and rainy. That is, it has a subtropical Mediterranean climate with dry summers and wet winters. The east coast of the continent is controlled by the western side of the subtropical high pressure in summer. The sinking air is originally drier, but it absorbs a large amount of water vapor from the warm and humid sea surface, thus bringing abundant precipitation and producing a subtropical humid climate. Due to the sharp contrast between land and sea here, a unique monsoon climate has been formed. Its notable characteristics are rainy summers and dry winters, with rainfall concentrated in the summer, which is exactly the opposite of the Mediterranean climate. If compared with the east coast of the UK at the same latitude, it is also completely different. There will be no long periods of rainy weather before and after the arrival of the summer monsoon in the mid-latitudes of the east coast of the United States. People have never felt the weather was hot and stuffy for a long time, and mold is unlikely to occur. It can be seen that the precipitation seasons are very different at the same latitude. Therefore, in the world, the plum rain season only occurs on both sides of the middle and lower reaches of the Yangtze River in my country, roughly from the east of Yichang, between 29 and 33 degrees north latitude, as well as in southeastern Japan and the southernmost part of the Korean Peninsula. In other words, plum rain is a weather and climate phenomenon unique to East Asia, and in my country it is a weather and climate phenomenon unique to the middle and lower reaches of the Yangtze River. The atmospheric circulation conditions for the formation of Meiyu front rainstorms generally include: ① There is a blocking high pressure or a stable high pressure ridge in the middle troposphere in the high latitudes of Asia, and the atmospheric circulation is relatively stable and seldom changes; ② The westerly circulation in the mid-latitudes is straight, and frequent short-wave activities provide cold air conditions for the Jianghuai region; ③ The western Pacific subtropical high pressure has an obvious westward extension and northward jump process, and the 500hPa subtropical high ridge line is stable between 20 and 25 degrees north latitude, and warm and humid air currents are transported from the edge of the subtropical high to the Jianghuai River basin. Under such circulation conditions, the Meiyu front lingers in the Yangtze and Huaihe River basins, often accompanied by southwest vortices and shear lines, and mesoscale systems are active on the Meiyu front. It not only maintains continuous precipitation during the plum rain season, but also provides sufficient water vapor for heavy rains. Meiyu front rainstorms are a special weather in a specific area formed by the interaction of circulation systems of different scales. The variability of atmospheric circulation causes the start of the Meiyu period to be earlier or later and the duration of the Meiyu period to be longer or shorter in each year. In some years, the Meiyu front is particularly active, with frequent rainstorms, causing floods and waterlogging disasters. In some years, the plum rain front is not obvious, resulting in an "empty plum rain season" and dry weather. In some years, the plum rain belt moves northward and then returns to the Yangtze and Huaihe River basins to maintain relative stability again, which is customarily called "inverted plum rain". After the plum rain season ends in the Yangtze and Huaihe River basins, the rain belt moves to North China, and the Yangtze and Huaihe River basins enter a period of high temperature and little rainfall.

The above content introduces us to the plum rain weather syndrome. Although we are in the north, we should go to the south to experience the rainy weather in the south and appreciate the unique customs and culture of the south. It is really a good place to travel. It is better to act than to be moved. Let’s make a plan now!