What does the autumnal equinox mean? What does the autumnal equinox mean?

Introduction: The arrival of the autumnal equinox means that people should start to add clothes to keep warm. The arrival of the autumnal equinox rings the bell of this autumn, and the climate of the whole country will drop greatly. The coolness that belongs to autumn has really come. Autumn, the most suitable season for travel, first of all, we must understand the meaning of the autumnal equinox, so what is the meaning of the autumnal equinox solar terms? What does the autumnal equinox mean? Follow me to have a look!

What does the autumnal equinox mean?

The autumn equinox has two meanings. The first floor means that day and night are the same, and the second floor means that autumn is equally divided, and the weather gradually turns from hot to cold.

On the day of the autumnal equinox, the point of direct sunlight reaches the longitude 180 (autumnal equinox), almost directly to the equator of the earth, and the length of day and night is the same all over the world (regardless of the refraction of sunlight by the atmosphere and the dim shadow in the morning). After the autumnal equinox, the direct point of the sun continued to move from the equator to the southern hemisphere, and the days in the northern hemisphere began to shorten and the nights became longer, that is, the days in a day began to be shorter than the nights; The southern hemisphere is the opposite. Therefore, the autumnal equinox is also called the landing point. At the North Pole and South Pole, on the day of the autumn equinox, the sun is on the horizon all day.

In the same solar term, every year is 6 hours or 5 hours later than the previous year, and the leap year is 24 hours earlier. In this way, the date reflects that the same solar term remains unchanged or lags behind the previous year 1 day; The leap year remains unchanged or is earlier than the previous year 1 day. In this way, the starting point of the same solar term has three different Gregorian calendar dates. Take the "autumnal equinox" as an example, there are three situations: September 22nd, September 23rd and September 24th.

Autumn equinox meteorological change

According to the lunar calendar, "beginning of autumn" is the beginning of autumn and ends with "the first frost". The "vernal equinox" is exactly half of the 90 days from beginning of autumn to the first frost. Since the autumnal equinox, the climate has three main characteristics: the direct sunlight continues to move from the equator to the southern hemisphere, and the phenomenon of short days and long nights in the northern hemisphere will become more and more obvious, with shorter days and longer nights (until the winter solstice reaches long nights and short days); The temperature difference between day and night gradually increases. The situation in the southern hemisphere is just the opposite. After the autumnal equinox, the direct sunlight moves south, the days in the northern hemisphere become shorter, the nights become longer, and the temperature drops, which is of universal significance throughout the country.

At the autumnal equinox, the Yangtze River basin and its vast northern area have entered autumn, and the daily average temperature has dropped below 22℃. The cold air mass in the north began to have some influence. The rainy season has just ended in most areas, with a cool breeze blowing gently. Autumn is crisp and the sky is high and the clouds are light. After the autumnal equinox, the direct sunlight moved to the southern hemisphere, and the northern hemisphere got less and less solar radiation, but the ground lost more heat and the temperature dropped significantly. Agricultural proverbs say: "An autumn rain is a cold", "The white dew is divided into autumn nights, and one night is cold".

Agricultural activities in autumn equinox

The characteristics of rapid cooling in autumn make "Sanqiu solar terms for health" particularly tense in the busy autumn harvest, autumn ploughing and autumn planting. The autumnal equinox is a good time to harvest cotton and tobacco leaves from green to yellow. Winter wheat has been planted in North China, and the Yangtze River basin and vast areas in the south are busy harvesting late rice and ploughing the land to prepare for rape sowing. Drought and lack of rainfall or continuous rainfall in autumn equinox are the main unfavorable factors affecting the normal operation of Sanqiu, especially the continuous rainfall will make the upcoming crops lodging, mildewing or sprouting, resulting in serious losses. "Sanqiu" is a great help, and the word "early" is the key. Timely harvest of crops in autumn can avoid the harm of first frost and continuous rain, and timely sowing of crops in winter can make full use of heat resources before winter, cultivate strong seedlings to survive the winter safely, and lay the foundation for high yield in the coming year.