Relationship between sunshine and solar terms

Simply put, the summer solstice in the northern hemisphere is the longest, the winter solstice is the shortest, and the vernal equinox is moderate. From summer solstice to winter solstice, the temperature drops, and vice versa.

At noon, the height of the sun (basically corresponding to the sunshine intensity) is the highest in summer solstice and the lowest in winter solstice north of the Tropic of Cancer.

Therefore, for most parts of China, the sunshine duration from summer solstice is the longest (like the whole country) and the sunshine is the strongest (south of the Tropic of Cancer, and the strongest is close to summer solstice). The solstice in winter is the shortest day and the weakest sunshine year in China.