Among the 24 solar terms, which solar term has the longest day?
Twenty-four solar terms are formulated according to the change of the position of the sun on the ecliptic, which can reflect the changes of seasons and phenology, and have been used by the ancients in China for a long time to guide agricultural activities.
On the day of summer solstice, the sun moves to 90 degrees of the yellow meridian, and the position of the sun directly on the ground reaches the northernmost point of the year, almost directly on the Tropic of Cancer. At this time, the daylight hours in all parts of the northern hemisphere reach the longest in the whole year. For the Tropic of Cancer and its northern area, the summer solstice is also the highest day of the year at noon.
The solstice in summer is the turning point of the sun. After this day, I went back. The direct sunlight point moved southward from the Tropic of Cancer, and the daylight in the northern hemisphere became shorter and shorter day by day. After the summer solstice, the height angle of the sun at noon will also decrease day by day in the Tropic of Cancer and its northern area. At the same time, after the arrival of the summer solstice, the stars in the night sky gradually became summer stars.
The ancient Chinese divided the twenty-four solar terms into three phases, namely, "the first phase of staghorn solution; Second, wait for cicadas to start singing; "Third-class Pinellia ternata" means that at this time of year, antlers begin to fall off, cicadas begin to sing, and Pinellia ternata and hibiscus gradually flourish and bloom. "Some creatures that love Yin began to appear, while positive creatures began to decline.
Like the winter solstice, the summer solstice is also a solar term reflecting the changes of the four seasons. Astronomy stipulates that the summer solstice is the beginning of summer in the northern hemisphere. Because the heat radiated from the sun to the ground is still more than the heat radiated from the ground to the air, and the temperature will continue to rise in the future, there is a saying that it is not too hot from summer to the sun.