When is the dragon in the climate and solar terms?

On June 2 1 or 22 of the Gregorian calendar every year, when the sun moves to 90 degrees of the yellow meridian, it is a summer solstice solar term. From summer to the sun, the sun directly reaches the northernmost point of the year, almost directly to the Tropic of Cancer (23 27' north latitude), and the daytime in the northern hemisphere is the longest, and the farther north it is, the longer it is. 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. At this time, the precipitation has a great influence on agricultural output, and there is a saying that "raindrops are worth tens of millions in summer solstice". 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. From summer to around, early rice heading and flowering in the south of Huaihe River, field water management should be fully water heading, wet irrigation, dry and wet, which not only meets the water demand of rice fruiting, but also can ventilate and nourish roots, ensure maturity and improve grain weight. As the saying goes, "Summer broadcast is not allowed for noon", we should pay close attention to the completion of summer broadcast, strengthen the management of broadcast content, and strive for full seedlings. After the seedlings emerge, they should be spaced, fixed and transplanted in time to make up for the deficiency. During the summer solstice, all kinds of weeds in farmland grow as fast as crops. They not only compete with crops for water, fertilizer and sunlight, but also parasitize various germs and pests. Therefore, the agricultural proverb says, "If you don't hoe the roots and weeds in the summer solstice, it's like raising a poisonous snake to bite you." Grasping intertillage and hoeing is one of the important measures to increase production from summer solstice. Generally, cotton has germinated, and its vegetative growth and reproductive growth are vigorous. Attention should be paid to ridging, intertillage and ridging in time, and ditch cleaning and drainage should be done in the field in rainstorm areas to prevent the harm of waterlogging and rainstorm. "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. After the summer solstice, the temperature will continue to rise for some time, and about twenty or thirty days is the hottest weather.

Twenty-four solar terms refer to twenty-four seasons and climate, which is a supplementary calendar made by China in ancient times to guide farming. As early as the Qin and Han Dynasties, the 24 solar terms had been completely established.

Since the main political, economic, cultural and agricultural activity centers in China are mostly concentrated in the Central Plains of the Yellow River Basin in history, the 24 solar terms were established on the basis of the climate and phenology in this area.

Twenty-four solar terms can reflect the changes of seasons, guide agricultural activities and affect the food, clothing, housing and transportation of thousands of families. April 20 14, the Ministry of Culture of China officially began to declare the "24 solar terms" to UNESCO's "Intangible Cultural Heritage of Humanity".

The 24 solar terms are formulated according to the position change of the sun on the ecliptic (that is, the orbit of the earth around the sun), so the dates of the solar terms are basically fixed in the current Gregorian calendar, with the first half of the year being 6 days and 2 1, and the second half being 8 days and 23 days, with a difference of 1 ~ 2 days.

Climatic characteristics of the twenty solar terms;

Beginning of spring: It refers to the solar terms that begin in spring.

Rain: At this time, when winter goes and spring comes, the temperature begins to rise and the air humidity keeps increasing, but the cold air activity is still very frequent.

Scare: refers to the hibernating creatures in hibernating soil that start to move in winter. It was cold and warm before and after the shock, and the temperature and wind changed greatly.

Vernal equinox: the sun shines directly at the equator, and the length of day and night is almost the same. Overwintering crops in vast areas of China will enter the spring growth stage.

Qingming: The temperature rises and the weather gets warmer.

Grain Rain: More rain is good for grain growth.

Long summer: Everything grows and prospers.

Xiaoman: Summer crops such as wheat are full, but immature. Miscanthus: At this time, the sun moves to 75 degrees of the Yellow Meridian. Crops with awns, such as wheat, are mature enough to collect seeds. Summer solstice: The sun shines directly on the Tropic of Cancer, resulting in the phenomenon of "the sun arrives in the north, the day is long and the shadow is short", so it is called "summer solstice". Slight heat: The intense heat marks the hot season in most parts of China.

Summer heat: just before and after the middle section. This period is the hottest period in a year in China's vast areas, but there are also abnormal years, "there is no heat in summer" and there is more rain.

Beginning of autumn: The vegetation begins to bear fruit, which is the harvest season.

Hot summer: "hot summer" means the end. When the summer heat draws to a close, the weather will get cool. As it is autumn harvest, precipitation is very precious. The Millennium: As the direct point of the sun moves southward obviously, the temperature drops rapidly and the weather is cool. Water vapor close to the ground at night forms white dew on vegetation, hence the name "white dew". Autumnal equinox: The point of direct sunlight returns to the equator, forming equal length of day and night. Cold dew wind: At this time, the direct point of the sun began to move south, the temperature in the northern hemisphere continued to drop, the weather was colder, and the dew was chilly, hence the name "cold dew wind".

First frost: The first frost period in the Yellow River basin is generally in the late period of 10, which coincides with the "first frost" solar term, and frost is very harmful to growing crops.

Beginning of winter: Winter has begun.

Xiaoxue: The cold air force in the north is strengthened, the temperature drops rapidly, and snowflakes appear in the precipitation. However, this is the first snow stage, with less snow and fewer times. Most of the Yellow River Basin snows after the "light snow" solar term. Heavy snow: at this time, the direct point of the sun is close to the tropic of Capricorn, and the days in the northern hemisphere are short and the nights are long. Winter solstice: At this time, the sun shines almost directly on the tropic of Capricorn, and the southern solstice, short day and long shadow form in the northern hemisphere, which is the shortest day of the year. After the winter solstice, the days in the northern hemisphere became longer and the temperature continued to drop, entering the "March 9" with the lowest annual temperature. Slight cold: At this time, the climate began to get cold.

Great cold: it's freezing, the coldest time of the year.

Several methods of dividing the four seasons;

The four seasons in temperate and subtropical regions are spring, summer, autumn and winter. One revolution of the earth around the sun is a year on the earth, and the solar heat received by the earth at different positions in the orbit is different, which leads to the seasonal change of alternating cold and summer on the earth. There are several ways to divide the four seasons:

1. Astronomical division method From the astronomical phenomenon, the change of four seasons is the seasonal change of the length of day and night and the height of the sun. In a year, the season with the longest day and the highest sun height is summer, the season with the shortest day and the lowest sun height is winter, and the transitional season between winter and summer is spring and autumn. Therefore, the astronomical division of the four seasons is based on the vernal equinox (March 2 1), summer solstice (June 2 1), autumn equinox (September 2 1) and winter solstice (February 2 1). Namely: spring from the vernal equinox to the summer solstice, summer from the summer solstice to autumn, autumn from the autumn equinox to the winter solstice, and winter from the winter solstice to spring.

2. The meteorological division method of meteorological department: March-May is usually spring, June-August is summer, 9-1 65438+1October is autumn, 12- February is winter,1,April, July and the following year.

3. In the ancient classification, beginning of spring (February 4th or 5th) is beginning of spring, Changxia (May 5th or 6th) is long summer, beginning of autumn (August 7th or 8th) is beginning of autumn, and beginning of winter (165438+1October 8th or 9th) is beginning of winter.

In China, it is customary to use the month of the lunar calendar to divide the four seasons. Lunar calendar1~ March is spring, April-June is summer, July-September is autumn, and 10 ~ 12 is winter. The first day of the first month is the first day of the year and the first day of spring, so it is also called the Spring Festival.

In China, weather temperature is also used as a standard to divide the four seasons. The average temperature is above 22℃ in summer, below 10℃ in winter and between 10℃ and 22℃ in spring and autumn. Due to the different climates, the length of the four seasons is different. The four seasons divided in this way can better represent the local actual seasonal cold and warm conditions. With this division method, we have found many places where there is no summer in winter, no winter in summer, all seasons are spring or all seasons are incomplete.

The standard of dividing the four seasons in the meteorological sense of Shanghai;

1. After entering beginning of spring in spring (around February 4th), if the average daily temperature is ≥ 10℃ for five consecutive days, it will be the first day of beginning of spring. (Annual average: March 25th) 2. Long summer (around May 5th) is summer, with the daily average temperature ≥22℃ for five consecutive days, and the first day is the first day of summer. (Annual average: June 2nd summer) 3. After beginning of autumn (around August 7th) entered autumn, the average daily temperature appeared < 22? C, it's autumn. Its first day is the first day of autumn. (Annual average: September 27th) 4. After entering beginning of winter in winter (165438+1around October 7th), the average daily temperature for five consecutive days is < 10? C, it's winter. Its first day is the first day of winter. (Annual average:165438+1October 28th)