Introduction of summer solar terms

Summer solstice solar terms introduce the origin and meaning of summer solstice.

Solstice is the earliest of the 24 solar terms. In the 7th century BC, the shadow of the sun was measured by civil soil gauge, thus the summer solstice was determined. According to "Zunxian Manuscript", "The sun arrives in the north, the days are long and the shadows are short, so it is called the summer solstice. At best, it is excellent. " On the day of summer solstice, the sun directly reaches the northernmost part of the year, almost directly to the Tropic of Cancer (23 26' north latitude), which is the longest place in the northern hemisphere. The farther north, the longer the day. For example, the daily length of Haikou in Hainan is a little more than 13 hours, Hangzhou is 14 hours, Beijing is about 15 hours, and Mohe in Heilongjiang can reach 17 hours. From summer to the future, the direct point of the sun began to move southward, the daytime in the northern hemisphere began to shorten gradually, and the noon sun height in the Tropic of Cancer and its northern area began to decrease day by day. There is a folk saying that "eating noodles in summer makes the day shorter", and Wei, a poet in the Tang Dynasty, also wrote in "Beichi Summer" that "the sun is cloudy and the night leaks from now on". At this time, the southern hemisphere is in the middle of winter.

In ancient China, the summer solstice was divided into three phases: "The first phase of staghorn dissolution; Second, wait for cicadas to start singing; Third-class Pinellia ternata. " Although Mi and Lu belong to the same family, the ancients thought they belonged to Yin and Yang. The deer's horn faces forward, so it belongs to Yang. On the solstice of summer, Yin Qi was born, and Yang Qi began to decline, so the front antlers began to fall off. Because mi belongs to yin, it falls in the corner of winter; After the solstice of summer, the male cicada fluttered and sang because of Yin Qi's feeling; Pinellia ternata is a shade-loving herb, named after it was born in swamps or paddy fields in midsummer. It can be seen that in the hot summer, some yin-loving creatures began to appear, while positive creatures began to decline.

China folks divide 15 days from summer to the future into three "hours", usually the first three days, the middle five days and the last seven days. During this period, the temperature in most parts of China was high, the sunshine was sufficient, the crops grew rapidly, and the physiological and ecological water demand was high. The precipitation at this time has a great influence on agricultural output, and there is a saying that "the rain from summer to the sun is worth a thousand dollars". In general, the precipitation in the middle and lower reaches of the Yangtze River and Huanghuai area can generally meet the requirements of crop growth. The Chronicle of Jingchu's Age says: "It rained on June 3rd, and the Tian family thought it was sweet, and the whole city congratulated each other." It can be seen that as early as 1000 years ago, people had a clear understanding of the characteristics of this rainfall.

What is the summer solstice?

What is the summer solstice?

The solstice in summer is the longest day and the shortest night in the northern hemisphere. On the day of the summer solstice, except the south pole of the Antarctic circle and the polar night area, the sunrise direction in all parts of the earth starts from the northeast and sets in the northwest.

Take Beijing as an example. In summer solstice, dawn begins at 2:42 am and gets up at 4:45 am. At night 19:46, 2 1:49 it was completely dark. The complete darkness lasted only about 5 hours, and the time when the sun was above the horizon was 15 hours. If we continue to go north, the night will be further shortened. In Nordic cities such as Stockholm, Helsinki and Oslo, the midnight sky is still bright, so you can read books under the night sky. When we reach the area north of 66.4 north latitude, we can see the midnight sun, which we think is a miracle. People there can enjoy sunbathing 24 hours a day.

Around the summer solstice, the earth is located near the perihelion, and its running speed is slightly slower, resulting in the sun spending 8 days more in the northern hemisphere than in the southern hemisphere in a year, so the summer in the northern hemisphere is slightly longer.

Characteristics of summer solstice

Characteristics of summer solstice

Although the summer solstice has the longest day and the highest sun angle, it is not the hottest time of the year. Because, close to the surface of the heat, at this time still continue to save, did not reach the maximum time. As the saying goes, "Hot days are in dog days", and the real hot weather is calculated by summer solstice and beginning of autumn. From mid-July to mid-August, the temperature is the highest in all parts of China, and the highest temperature in some areas can reach about 40 degrees.

"However, the summer solstice is not hot." "The summer solstice is already three years old." Although the summer solstice indicates that the hot summer has arrived, it is not the hottest time. The temperature will continue to rise for some time after the summer solstice, and it will be the hottest weather in about twenty or thirty days. 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 summer rain over the mountains. In the south, Liu Yuxi, a poet in the Tang Dynasty, skillfully used this weather and wrote a famous poem about the sunrise in the east and the rain in the west, saying that there is no sunny, only sunny.

There are tricks to replenish water from summer solstice.

In hot summer, a lot of sweating will cause dehydration of the body, affecting physiological function and exercise state. Studies have shown that if the amount of dehydration reaches 2% of body weight, the heat resistance of the body will be affected; When dehydration reaches 4%, it will affect muscle endurance; When dehydration reaches 10%, it will affect coordination ability and even make muscles spasm; The most serious situation of dehydration is to increase body temperature, circulatory failure and even death. During exercise, pay attention to the following items when replenishing water:

First, the temperature of drinking water should be appropriate. The water temperature should be controlled at 8℃- 14℃, because water at this temperature can quickly pass through the stomach.

Second, drink some water before exercise. You can drink 10- 15 minutes before exercise.

Third, hydration should follow the principle of drinking more. It is best to drink/kloc-0 for 20-30 minutes each time during exercise, and drink 1 50-200ml each time.

Fourth, add light salt water. If you lose more water and salt after exercise, you can drink some light salt water, or put more salt in the soup when you eat.