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

1. During the summer solstice, the daytime in the northern hemisphere is the longest. From this moment on, the days in the northern hemisphere gradually shorten. At the autumnal equinox, day and night 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 winter solstice, the days in the northern hemisphere begin to get longer until the vernal equinox.

If your question is when the days are shorter than the nights in the northern hemisphere, it should be from the autumnal equinox to the vernal equinox.

If you want to ask about the shortest day, it is from the solstice in summer to the solstice in winter.

On the solstice of summer, the sun shines directly on the Tropic of Cancer, which is the longest day of the year in the northern hemisphere. It takes about fourteen hours from sunrise to sunset in all parts of Sichuan. Although the summer solstice has the longest day and the highest sun height, it is not the hottest time of the year. 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 in the Tang Dynasty, skillfully took advantage of this weather and wrote a famous poem, "Rising in the east and descending in the west, the road is sunny and sunny."