How do people judge the beginning and end of the rainy season?

In the middle and lower reaches of the Yangtze River in China, Taiwan Province Province, south-central Japan, South Korea and other places, there will be continuous rainy weather in June and July every year. Because it is the mature period of plums in Jiangnan, it is called "Meiyu", and this period is called Meiyu season. In the rainy season, the air humidity is high and the temperature is high, so clothes are easy to get moldy, so some people call the rainy season "moldy rain". After the rainy season, the weather began to be dominated by the Pacific subtropical high and officially entered the hot summer.

There are many folk proverbs about plum rains in China, such as "No east wind on March 9th, no rainstorm in Huangmei", "March 9th" refers to the solar calendar 65438+1October 9th-17, and "Huangmei" refers to the solar term (June 6th-20th). This proverb means that if there is no east wind during the third nine-year plan period, or there is little east wind, the solar term rainfall of mango will be less. The first day of March 9 is about 150 days from the first day of the solar term of mango. According to the rhythm of 150 days, there will be a similar repeating process every 150 days. Therefore, there is a corresponding relationship between the easterly wind and the precipitation of mango solar terms. There are many proverbs that use winter weather characteristics to predict plum rains. For example, "there is more snow in the twelfth month, and the water is yellow and plum", which means that the snow in the twelfth month is positively related to the plum rain. "Cold water is dry, summer water is dry", and "dry" means less rain. As the saying goes, if there is less rain in winter, there will be less plum rain. This is because the weather often has stages. Persistent drought is often caused by the relative stability of a weather situation conducive to drought. However, due to the constant movement of the atmosphere, the above-mentioned relatively stable state will always be destroyed and will turn to the opposite side under certain conditions. "Peach blossom water must dry plum", and "Peach blossom water" refers to the Tomb-Sweeping Day air or precipitation when peach blossoms open in April. "Dried Huangmei" means that the rainy season of awn seeds is less or the rainy season starts later. In the lower reaches of the Yangtze River, if there is more rain in Tomb-Sweeping Day or peach blossom period in April, which is commonly known as "peach blossoms are exhausted", the rainy season of mango will be less, or the rainy season will start later. "Peach blossoms fall in the mud and wheat hits the dust; Peach blossoms fall in the dust and wheat hits in the mud, which is similar to this meaning. Too much peach blossom water often indicates that the Pacific subtropical high is stronger than normal in spring, and the warm and humid airflow is active. In the atmosphere of Tomb-Sweeping Day where peach blossoms are open, cold air from north to south often meets and confronts in Jiangnan and Shanghai, resulting in too much peach blossoms. In June, during the solar term, the subtropical high forces often update relatively weakly, or jump slowly to the north, resulting in less plum rains or starting late, resulting in an inverse correlation between the rainfall in the two periods. " Spring water overflows and summer water dries up "and" flooding "means that there is more rain than normal. As the saying goes, if there is more rain in spring, there will be less plum rain in summer, which is easy to dry. It is the same as "peach blossoms must be dried plum blossoms", and it uses spring rain to predict plum rains. If there is a spring breeze, there must be a summer rain. Spring breeze refers to the east wind (mostly southeast wind), and summer rain refers to plum rain. The proverb means that when there is a lot of easterly wind in spring, there is usually a lot of plum rain in summer. "Xiaoman is not satisfied, Huangmei doesn't care", which shows that Xiaoman has a positive correlation with the solar terms of mango, that is, Xiaoman has less rain, which means that the solar terms of mango will also have less rain, or Huangmei will be late. This is because the Xiaoman solar term is the turn of spring and summer. If there is less rain during this period, it reflects that the subtropical high is weak and located in the south. In the solar terms of the canopy, the subtropical high generally does not increase rapidly. Even if there is a certain intensity, the southwest airflow at its northern edge will not extend to the lower reaches of the Yangtze River, so there will be less rainfall in the lower reaches of the Yangtze River. The precipitation in Xiaoman solar term is also called "dry Huangmei" in the lower reaches of the Yangtze River, "positive Huangmei" in Mang solar term and "sweet Huangmei" in summer solstice solar term. Therefore, it is called "Huangmei doesn't care" if there is little rain on the mountain or the plum rain falls late (it doesn't start until the summer solstice). These people's experience of seeing the sky is verified by local meteorological data, and the accuracy rate is 70% to 80%. In other words, if it is predicted ten times, it will be correct seven or eight times. This shows that the proverb about plum rain is credible.