The spring breeze is green again and meteorological knowledge on the south bank of the river

"The spring breeze turns the south bank of the river green again" comes from Wang Anshi's poem. At that time, the poet looked at the south of the Yangtze River and looked for the return of spring, and he felt emotional in his heart. The ancients first collectively referred to frost, snow, ice, thunder, etc. as phenology. Although phenology and climatology can be called sister sciences, the observation of phenology is much earlier than that of climate. The difference between the two is that climatology is the observation and recording of changes in cold, warm, sunny, rainy, and wind and clouds in a place, and infers its causes and trends. Phenology records the growth and decline of plants and the comings and goings of animals throughout the year to understand climate change and its impact on animals and plants. Observing climate records the local weather at that time, such as wind, rain, cold and heat, etc. on a certain day in a certain place; while phenological records, such as willows green, peach blossoms blooming, swallows beginning to come, etc., not only reflect the weather at that time, but also reflect The accumulation of weather over a past period. Many great poets in my country's Tang and Song Dynasties were concerned about the people's livelihood and collected a large number of bamboo branches and folk songs from various places; on the other hand, they loved nature and were good at understanding the hints of birds singing and fragrance of flowers. They imitated these folk songs and bamboo branches and wrote verses. The moon, dew, wind, clouds, flowers, and birds are a language of nature. Through this language, we can understand the essence of nature, that is, the laws of nature, and poets can better grasp the meaning of such language. Therefore, it can be written into poetry and passed down to future generations. From the perspective of natural rhythms, phenology is about the changes and cycles of the moon, dew, wind, clouds, flowers, and birds throughout the year. Great poets of the Tang and Song Dynasties made great contributions to the singing of phenology. In his later years, Wang Anshi wrote a poem: "The spring breeze is green again on the south bank of the Yangtze River. The weather is high in Beidian. When will the bright moon shine on me again?" After verification by later generations, when Wang Anshi wrote this poem, it was originally written as "The spring breeze is coming to the south bank of the river again." After repeated After careful consideration, I felt that the word "arrive" was not satisfactory, so I changed it several times before writing the word "green". Li Bai and Wang Anshi all used the word green in their poems to symbolize the arrival of spring. Today, in phenology, the greening of flowers and trees has become one of the important indicators of the arrival of spring. The greening of trees is a very important indicator of early spring, that's for sure. However, various trees bloom at different times. Which tree's blooming time can be regarded as an indicator of early spring? Judging from the chants of Tang and Song poets, willow is the most valued. The reason why Yangliu Drawing Green was chosen as the representative of early spring is no accident. Firstly, because willow trees bloom early; secondly, because it is distributed over a wide area, from Wuling in Nanling in the south to outside the pass in the north. It is not afraid of wind and sand, nor is it too low-lying.