The origin of the summer heat of the 24 solar terms.

1, the origin of solar terms: "Dou Zhixin is light in summer, when the weather is already hot and it has not reached the silt pole, hence the name". On a small summer day, the sun reached 105 degrees. At noon, measure the shadow of the sun with a standard measuring tool. The length of the shadow is 2 feet 4 inches, which is equivalent to 0.58 meters today. Compared with the solstice in summer, the days are getting shorter. At night, observation shows that the perch of the Big Dipper points in an unknown direction, that is, southwest. This stage is usually in June of the lunar calendar, also known as the last month. It's already very hot, but it's not the hottest time yet, so it's called Xiaoshu.

2. The summer solstice is the eleventh solar term in the twenty-four solar terms of the lunar calendar, and the fifth solar term in summer indicates the official start of the last month of summer; On July 7th or 8th every year, when the sun reaches longitude 105, it is a summer solar term. Twenty-four solar terms: June Festival? Summer, summer, size, small at the beginning of the month, big in the month, and still small today. "Summer heat, which means hot, is slightly hot. The ancients thought that the summer heat period was not the hottest time of the year, so it was called summer heat. There is also a solar term ballad: "Little summer is not hot, but big summer lasts for three days. "It is pointed out that the hottest period of the year has arrived, but it has not yet reached an extremely hot level. As the saying goes, "the heat is at three volts." The dog days in China generally appear on the 28th day after summer, which is the so-called "summer is the first night". "

People often say that "the heat is at three volts". According to the China calendar, the third Geng day from summer to the future is declination, in which the first declination is 10, the first declination is 20 days from the summer solstice, and the latest is 30 days, and the summer solstice is 16. "After long summer, it's three minutes hot every day", and the period from long summer to beginning of autumn happens to be "long summer", that is, "dog days", which is the highest temperature in the whole year. There is a folk saying that "summer heat comes one after another, and it is too hot to hide" and "steaming in summer heat". "In summer, rain and heat are in the same season." Rain and summer are interdependent. Pang Zhu, a poet in the Jin Dynasty, wrote in his poem "Celebrating Summer": "If you are afraid of summer shortage, you will retreat. Young slaves were recommended as pillows, and yellow milk was promoted to the church. Birds are singing in the dark, and the rain carries the fragrance of lotus leaves. Nothing in the evening, step _ West Chamber. "

4. In ancient China, the summer heat was divided into three periods: "First, it was warm and windy; Second, wait for crickets to live in space; The third waiting eagle began to crow. " In summer, there is no cool wind on the earth, and all the winds carry heat waves; The words describing crickets in the Book of Songs in July are "Wild July, August, September at home, October in bed." August mentioned in this paper is June in the summer calendar, which is a short time in summer. Because of the heat, crickets leave the field and go to the corner of the yard to escape the heat. In this solar term, the eagle is in the cool high air movement, because the ground temperature is too high.

5. There is a folk saying called "Little summer and big summer, steamed and eaten". Because of sweating, exhaustion and fatigue, people can't ignore the maintenance of their bodies. At this time, the Meiyu in the Jianghuai Basin is coming to an end, and the temperature in long summer has risen and entered the summer drought period; However, when North China and Northeast China entered the rainy season, tropical cyclones were active frequently, and the number of tropical cyclones landing in China began to increase. After the summer, the south should pay attention to drought resistance and the north should pay attention to flood control. Crops all over the country have entered a vigorous growth period, and it is necessary to strengthen field management.