Manuscript about the first frost and the first frost.

1, the first frost is the last solar term in autumn and the transition from autumn to winter. In the first frost season, everything is finished, everything goes to heaven, the sun goes to the ground, and the yin begins to condense. The cold weather began with the first frost. [Yi Zhoushu Zhou Yue]: "Autumn and March are empty: summer, autumn equinox, first frost." In Lun Heng, Wang Chong of the Eastern Han Dynasty said: "Clouds and fog are also signs of rain, while summer is dew, winter is frost, temperature is rain, cold is snow, and rain and dew are frozen, all from the ground, not from the sky." Whether it is dew or frost, "it comes from the ground, not from the sky." How can it be called first frost? In fact, the name "first frost" is just a metaphor.

2. Because "frost" is a manifestation of cold weather and large temperature difference between day and night, it is named "first frost", which means "sudden drop in temperature and large temperature difference between day and night". The "first frost" solar term reflects the climatic characteristics of the cold weather, but it does not mean that it will be "frost" when entering this solar term. In fact, "frost" didn't fall from the sky. The "frost" is the condensation of water vapor on the ground when it meets cold air due to the change of temperature difference. The solar term "first frost" has nothing to do with "first frost".

3. The "first frost" solar term is characterized by cold weather in the morning and evening, hot weather at noon, large temperature difference between day and night, and obvious autumn dryness. On the national average, the first frost is the season with the largest temperature difference between day and night in a year. After entering the first first frost solar term, the cold air activities affecting our country became more and more frequent, and the temperature difference between day and night increased rapidly. Especially in Jiangnan and South China, the temperature fluctuation is more and more obvious; Some areas in northwest and northeast China have shown the scene of "cold wind and fallen leaves" in early winter.

4. The first frost period is generally from the end of June 10 to1early October 10. With the dry and cold air gradually dominating the whole country, warm and humid air is marginalized, and many weather with the characteristics of summer and early autumn exits, and the weather is relatively simple. Before and after beginning of winter, there were often strong winds and cool weather, and some places entered winter in a short time.