How did Xiaoxue's solar terms come from?

Every year165438+1October 22nd and 23rd, when the sun reaches 240 degrees of the longitude of the Yellow River, it is light snow. Twenty-four solar terms: "In the middle of June of 5438+00, it rained and was blown thin by cold air, so it condensed into snow. The words of the villain are not prosperous. " During this period, the weather gradually became cold, and the average first snow period in the middle and lower reaches of the Yellow River was basically the same as the Light Snow Festival. Although it began to snow, the amount of snow was generally small, and it was frozen at night and turned around by day. If the cold air is strong and the warm and humid airflow is active, it may snow heavily. For example, on June 5438+0993165438+1October 15 ~ 20, there were heavy snowstorms in some winter wheat areas in the north.

Light snow is a solar term, because there are few snows and the amount of snow is not large, so it is called light snow. It can be seen that light snow indicates the beginning time and degree of snowfall. Light snow, like rain and Grain Rain, is a solar term that directly reflects precipitation.

The meaning of "light snow" in light snow solar terms is different from that in daily weather forecast. Xiaoxue solar term is a climate concept, which represents the climate characteristics during Xiaoxue solar term. The light snow in the weather forecast refers to the snow with less snowfall intensity. Meteorologically, when it snows, the horizontal visual distance is equal to or greater than 1000m, the ground snow depth is less than 3cm, and the snowfall in 24 hours is 0. 1? The snowfall between 2.4 mm is called "light snow".

In ancient China, light snow was divided into three stages: "When the rainbow disappeared; Second, the weather is rising and the atmosphere is falling; It was blocked three times and became winter. " The yang in the sky rises and the yin in the ground falls, which leads to the impassability between heaven and earth and the disharmony between yin and yang, so everything loses its vitality, and the heaven and earth are blocked and become a cold winter.

Before and after the light snow, agricultural production in most areas of China began to enter winter management and farmland water conservancy capital construction. The north wind is blowing and snowflakes are floating, and the area north of the Yellow River has reached Mengdong. At this time, the first snow will appear in northern China. Although the amount of snow is limited, it reminds us that it is the season to keep out the cold and keep warm. Before and after the light snow solar term, the weather is often cold and gloomy, and people's mood will also be affected by it at this time, especially those friends with depression are more likely to aggravate their illness, so in this solar term, friends must learn to recuperate themselves in days with less light.

"Xiaoxue" is in the second half of the solar calendar 1 1 and the second half of the lunar calendar in October. "Light Snow" is a festival that reflects weather phenomena. The ancient book "Qunfangpu" said: "A light snow will snow when it is cold, but the ground is not cold and the snow is not heavy." That is to say, due to the cold weather, in the "light snow" festival, the form of precipitation changed from rain to snow, but at this time, because the ground is not very cold and the amount of snow is not large, it is called light snow. With the coming of winter, the climate is getting colder and colder. Not only the dew on the ground turns into frost, but also the rain in the sky turns into snowflakes. After the snow fell, the earth was covered with white clothes. However, because the weather at this time is not too cold, the snow is often half frozen and half melted, or melts immediately after landing, which is called "wet snow" in meteorology; Sometimes rain and snow fall together, which is called "sleet"; Sometimes white ice particles as big as rice grains fall, which is called "rice snow". The precipitation in this solar term is still relatively scarce, which is far from meeting the demand of winter wheat. Morning fog is not just the last solar term.

Light snow indicates the beginning time and degree of snowfall. Snow is the product of cold weather. Light snow solar terms, the northern part of the southern region began to enter winter. "There is no rain in the lotus, but there are frost branches in the chrysanthemum", which has already shown the scene of early winter. Due to the barrier of Qinling Mountain and Daba Mountain in the north, the invasion of cold air is blocked and the severity of cold wave is reduced. The "warm winter" in South China is remarkable. The number of snowfall days in the whole year is mostly less than 5 days, which is much less than that in the middle and lower reaches of the Yangtze River at the same latitude. There is little chance of snowfall before the heavy snow. Even in the middle of winter, you can rarely see the charming scenery of "blowing open the petals of ten thousand pear trees". Because the surface temperature in South China is often above 0℃ in winter, it is more difficult to snow than to snow. Occasionally, although the sky is buzzing, there is no "broken jade" on the ground. In the cold northwest plateau, it usually begins to snow all the year round 10. The number of snowfall days in the northwest of the plateau can reach more than 60 days a year, and snowfall is possible in some alpine regions all year round.

Interpretation of the formula: Y= two digits after the number of years, D=0.2422, L= leap year, 2 1 century C=22.36, and 20th century =23.08.

For example, the date of light snow in 2088 = [88× 0.2422+22.36]-[88/4] = 43-22 = 2 1.165438+1October 21light snow. Exception: 1978 plus 1 day.