The Summer Solstice is one of the 24 solar terms. It is on the 21st or 22nd of June each year. On the summer solstice, the daytime in the northern hemisphere reaches the peak of the year. For the Tropic of Cancer and its northern region, the sun elevation is also the highest of the year at noon. In the Beijing area, the daytime can be as long as 15 hours. The solar radiation obtained in the northern hemisphere of this day is the most, nearly double that of the southern hemisphere.
Astronomer said that the summer solstice is the turning point of the sun, and after this day the sun will take a "back road," and the direct sunlight point will gradually begin to move southwards from the Tropic of Cancer. The daytime in the Northern Hemisphere will begin to gradually become shorter. After the summer solstice, the height of the sun at the noon began to decrease day by day on the Tropic of Cancer and its northern region. At the same time, after the summer solstice, the stars in the night sky gradually turned into a summer one.
The summer solstice is not only an important solar term, but also an important traditional Chinese folk festival. The summer solstice is one of the oldest festivals in China.
During the summer solstice, it was time to harvest. Since ancient times, there have been celebrations of harvest as well as sacrifies to ancestors in order to pray for the relief of disasters and an abundant year. Therefore, the summer solstice,as a holiday, included in the ancient ritual ceremony code.
Although the summer solstice shows that the hot summer has arrived, it is not the hottest time. The temperature continues to rise for several days after the summer solstice. It takes about twenty to thirty days to reach the hottest day.