What is the autumnal equinox? What are its characteristics?

The autumnal equinox is the sixteenth of the twenty-four solar terms, and the time is generally from September 22 to 24 of the Gregorian calendar every year; It is characterized by cold weather, falling temperature and equal day and night.

1, the weather turned cold.

The autumnal equinox solar terms are the solar terms that transition from early autumn to late autumn. By this solar term, most parts of the country have begun to enter the cool autumn. The cold air in the south meets the gradually decaying warm and humid air, and the rainfall will take away the heat on the ground and lower the surface temperature. Therefore, after the autumnal equinox, the weather will gradually cool down and the temperature difference at night will gradually widen.

2. The temperature drops

After the autumnal equinox, the direct point of the sun began to enter the southern hemisphere from the equator, and the northern hemisphere began to have shorter days and longer nights, and the day began to be shorter than the night in a day.

3. Distribute day and night equally

On the day of the autumnal equinox, the time between day and night on the earth is almost equally divided, with each day and night accounting for about 12 hour, which is also the origin of the name "autumnal equinox". At this time, the sunshine in the northern and southern hemispheres is relatively uniform, the temperature around the earth is gradually suitable, and the difference between cold and summer that people feel begins to narrow. After the autumnal equinox, the days get shorter, the nights get longer, the weather gets colder, the temperature drops, and people begin to transition from hot summer to cool autumn.

The phenomenon and custom of autumnal equinox;

1, phenological phenomenon

There are three stages in the autumnal equinox: the first stage is when the thunder stops, the second stage is when the insect bites, and the third stage is when the water dries up. The ancients thought that it thundered because the yang was strong and the yin began to flourish after the autumnal equinox, so it stopped thundering. Some insects unearthed at the vernal equinox will return to the soil after the autumnal equinox to prepare for winter. The water vapor is not so abundant and will start to dry up gradually, so the air is getting drier and drier.

2. Farming customs

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.