When does the day get shorter in the 24 solar terms?

Among the 24 solar terms, the days become shorter after the autumnal equinox. The days in the northern hemisphere are getting shorter and shorter. At the autumnal equinox, the day and night in the northern hemisphere are the same. From the autumnal equinox to the winter solstice, the day is shorter than the night, and the day in the northern hemisphere is the shortest. From the solstice of winter, the days in the northern hemisphere get longer and longer until the vernal equinox.

Because the heat in the near-surface layer is still accumulating at this time, and it has not reached its maximum. The solar term from summer solstice is the solar term with the largest annual rainfall in the eastern part of the basin, which is often controlled by subtropical high in the future, resulting in summer drought. In order to enhance drought resistance and win a bumper harvest in agriculture, it is an important measure to capture and store pre-dormant rainwater in these areas.

After the summer solstice, the ground is heated strongly and the air convection is strong, and thunderstorms are often easy to form in the afternoon to evening. This kind of hot thunderstorm comes and goes, and the rainfall range is small. People call it "dividing fields in summer and rain".

In Sichuan, Liu Yuxi, a poet of the Tang Dynasty, skillfully used this weather to write a famous poem "Rising in the east and descending in the west, the road is sunny and sunny".