On the vernal equinox, the sun shines almost directly on the equator of the earth, and the whole world is almost as long as day and night. At the vernal equinox, the direct point of the sun is on the equator, and the first ray of sunshine will be seen on this day, and the corresponding South Pole will also bid farewell to this day's sunshine. After the vernal equinox, the position of direct sunlight moves north.

2. Air pressure conditions

During the spring equinox and solar terms, the East Asian trough is obviously weakened, and the trough ridge activity in the westerly belt is obviously enhanced. From Mongolia to the northeast, there are often low-pressure activities and cyclone development. Low-pressure movement causes cold air to go south, and it is windy and windy in the north.

3. Weather duration

At the vernal equinox, theoretically, the length of the world from day to night is equal. After the vernal equinox, the days in the northern hemisphere are getting longer and shorter, and the nights in the southern hemisphere are getting shorter and shorter.

4. Temperature and precipitation

During the vernal equinox, the daily average temperature in all parts of China rose steadily to above 0℃ except the alpine mountain area and the area north of 45 north latitude.

According to the climate law, the precipitation in Jiangnan increased rapidly at this time, and it entered the period of "peach blossom flooding" in spring; In the northeast, north and northwest regions where "spring rain is as expensive as oil", precipitation is still very little, so resisting the threat of spring drought is the main problem of agricultural production.

Folk activities are generally considered as the official start of an outing. Activities include:

(1) Flying kites, women and children flying kites. And write a blessing on the kite, hoping that the gods in the sky can see it.

(2) Drinking with fragrant flowers: men, women and children use fragrant flowers.

(3) Picking wild vegetables in the wild: Zhu's "Ten Miscellaneous Books in Spring": I am not in the mood to pick wild vegetables when writing and playing the piano. In terms of diet, there are spring vegetables, spring soup and spring wine.

The extended data vernal equinox is the midpoint of 90 days in spring. One of the 24 solar terms, around March 20 of the Gregorian calendar every year, when the sun is located at 0 (vernal equinox) of the yellow meridian. On the vernal equinox, the sun shines directly at the equator of the earth, and the seasons in the northern and southern hemispheres are opposite. The northern hemisphere is the vernal equinox and the southern hemisphere is the autumnal equinox. The vernal equinox is a new year in Iran, Turkey, Afghanistan, Uzbekistan and other countries, with a history of 3,000 years.

Twenty-four solar terms: "in mid-February, half a minute, that is, half of 90 days, so it is called minutes." Autumn is synonymous. " "Spring and Autumn Stories Yin and Yang in and out" said: "The vernal equinox, Yin and Yang are also half-phase, so it is cold and summer day and night."

The vernal equinox is also a festival and ritual celebration. The ancient emperors had a system of offering sacrifices to the sun in spring and the moon in autumn. The ritual of the Zhou Dynasty was to offer sacrifices on the altar.

Book of Rites: "Altar." Ying Da Shu by Confucius: "Also called vernal equinox". In the Qing Dynasty, Pan Rongbi wrote "Ji Sheng at the age of Emperor Jingdi": "The vernal equinox and autumn are divided into national gifts, and scholars should not worship them.

References:

Baidu encyclopedia-vernal equinox