What are the phenological characteristics of the autumnal equinox solar terms? Ant manor.

Expand knowledge:

Autumnal equinox:

1, Introduction

The autumnal equinox is the sixteenth solar term among the twenty-four solar terms and the fourth solar term in autumn. Fight refers to unitary; The sun reaches the yellow meridian180; Celebrated on September 22-24 of the Gregorian calendar every year. On the day of the autumnal equinox, the sun shines almost directly on the equator of the earth, and the length of day and night is equal all over the world.

The autumnal equinox means "equally divided" and "equally divided", which means equally dividing autumn except day and night. After the autumnal equinox, the position of direct sunlight moves south, and the days in the northern hemisphere become shorter, the nights become longer, the temperature difference between day and night increases, and the temperature drops day by day.

The autumnal equinox used to be the traditional "Moon Festival", and the Mid-Autumn Festival evolved from the "Autumn Moon Festival".

2. Astronomical calendar

On the day of the autumnal equinox, the point of direct sunlight reaches 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.

3. Agricultural activities

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.