Traditional Culture Encyclopedia - Weather inquiry - What is the second sentence of "Spring in May came back late"?

What is the second sentence of "Spring in May came back late"?

Spring returns late in May, and weeping willows do not hang silk in February.

Weather and climate in ancient poetry

The climate difference between the north and the south in eastern China. In May, the ice and snow have not melted, and there is no spring scenery.

In the Tang Dynasty, Zhang Jingzhong's "Bian Ci" also wrote:

Spring is not too late in Wuyuan, and weeping willows are not hung in February.

That is, today's riverside ice opens, and it is the time when Chang' an flowers fall.

Wuyuan is today's Wuyuan County, Inner Mongolia Autonomous Region, and there is no willow in February. By the time the glaciers along the river thawed, Chang 'an City had fallen.

How to explain this phenomenon? It turns out that we feel that the temperature of the climate does not change directly with the angle of sunlight, but with the heat released by the earth receiving sunlight.

Since the beginning of spring, the earth has accumulated enough heat after almost two months. Therefore, the most scientific method is the climatology method, which takes the temperature as the standard and takes five days as the waiting period. The average temperature is below 10 degrees Celsius in winter, above 22 degrees Celsius in summer, and between 10 and 22 degrees Celsius in spring and autumn. According to this standard and referring to phenological changes, we can see that the arrival of spring is early and late, and the stay time in different regions and heights is long and short.

Spring in Fujian and Zhejiang mostly begins in late February, in the Yangtze River valley in March, and in Beijing and Tianjin until early April. Spring in Heilongjiang often comes around the long summer, but there is no spring at all in the alpine areas above 4000 meters in the north and 4300 meters in the south of the Qinghai-Tibet Plateau.