Spring breeze is green. Jiang Nanan's meteorological knowledge

Spring Breeze and Green Jiang Nanan is from Wang Anshi's poem. At that time, the poet looked forward to the spring return of Jiangnan, and his heart was filled with emotion. The ancients first called frost, snow, ice and thunder 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 to observe and record the cold, warm, sunny and rainy weather in a place, and infer its causes and trends; Phenology is to record the growth and decline of plants and the life and death of animals in a year, so as to understand climate change and its influence on animals and plants. Observing the climate is to record the local weather at that time, such as windy, rainy, hot and cold. Phenological records, such as Liu Qing, Tao Hua and Yan Shilai, not only reflect the weather at that time, but also reflect the accumulation of weather in the past period. Many great poets in the Tang and Song Dynasties in China, on the one hand, cared about the sufferings of people's livelihood and collected a large number of Zhi Zhu ci and folk songs from all over the country; On the other hand, he loves nature and is good at understanding the hints of birds and flowers, imitating such folk songs and bamboo branches and writing poems. Moon, dew, wind, clouds, flowers and birds are a language of nature. Through this language, we can understand the nature, that is, the laws of nature, and poets can better grasp the meaning of this language, so they can write poems and pass them on to future generations. In the sense of natural rhythm, phenology is a cyclic process of moon, dew, wind, clouds, flowers and birds in a year. Great poets in 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 in Jiang Nanan is green, the weather in Gaobeidian, when will the bright moon shine on me?" Later generations verified that when Wang Anshi wrote this poem, it was originally written as "Spring Breeze Comes to Jiang Nanan Again". After repeated deliberation, he thought that the word "Zhi" was inappropriate and changed it several times before writing the word "Qing". Li Bai and Wang Anshi use green words to symbolize the arrival of spring in their poems. Today, in phenology, the flowering of flowers and trees has become one of the important signs of the arrival of spring. To be sure, the greening of trees is a very important indicator in early spring. However, all kinds of trees paint green at different times. What kind of tree can be regarded as an indicator of early spring? Judging from the chanting of poets in Tang and Song Dynasties, Liu Yang is the most valued. It is no accident that willow was chosen as the representative of early spring. First, because willows bloom early; Secondly, because it is widely distributed, it is everywhere from Wuling in Nanling to Beiguan. It is not afraid of wind and sand, and it is not too low-lying.