24 solar terms Traditional Day

How are the 24 solar terms determined?

The earth revolves around the sun at 5: 48: 46 every 365 days and rotates once every 24 hours. Because the orbital plane of the earth's rotation is not the same as the equatorial plane, but maintains a certain inclination angle, the position of direct sunlight on the earth is different all year round. In the northern hemisphere, when the sun is directly at 23.5 degrees north latitude, it is called summer solstice in astronomy; When the sun shines directly at 23.5 degrees south latitude, it is called the winter solstice; The solstice in summer and the solstice in winter mean that it is halfway between summer and winter. Twice a year, when the sun shines directly on the equator, it is the vernal equinox and the autumnal equinox, in the middle of spring and autumn. The day is as long as the night. The solar terms reflecting the changes of the four seasons are: beginning of spring, Spring Equinox, Long Summer, Summer Solstice, beginning of autumn, Autumn Equinox, beginning of winter and Winter Solstice. Among them, beginning of spring, Changsha, beginning of autumn and beginning of winter are called "Li Si", which means the beginning of the four seasons. There are five solar terms reflecting temperature changes: slight summer heat, great summer heat, summer heat, slight cold and severe cold. There are seven solar terms reflecting weather phenomena: rain, Grain Rain, white dew, cold dew, first frost, light snow and heavy snow. There are four solar terms reflecting phenological phenomena: Jing Zhe, Qing Ming, Xiaoman and Mang Zi.

Beginning of Spring

Since the Qin Dynasty, beginning of spring has been the beginning of spring in China. Beginning of spring is divided from astronomy, but in nature and people's minds, spring is warm and flowers are fragrant. Spring is growth, cultivation and sowing. In climatology, spring refers to the period when the average temperature is between 10℃ and 22℃. Speaking of beginning of spring, people obviously feel that the days are getting longer and the sun is getting warmer. Temperature, sunshine and rainfall are often at the turning point of the year and tend to rise or increase. The growth of crops in early spring is accelerated, and the water consumption for bolting rape and jointing wheat is increased. Irrigation and topdressing should be done in time to promote growth. Agricultural proverbs remind people: "When it begins to rain in spring, get up early and go to bed late." Da Chun also began to prepare for farming. Although "spring" has been established, frost will still appear in most areas of the basin. In a few years, there will be a scene of "snow can't reach spring, so it flies through trees". These climatic characteristics should be taken into account when arranging agricultural production. Where is the information that people often look for in spring? The buds protruding from the wicker are "softer than gold and softer than silk"; The eager grass in the soil is waiting for "they grow taller in the spring breeze"; In order to win a new harvest, people who work hard in the fields are creating real spring with their hands.

Rain Water

The rainy season means that it begins to rain and the rainfall gradually increases. In the Yellow River valley, the birthplace of the 24 solar terms, it was cold before the rain, but it was snowing and raining unpleasantly. After the rain, the temperature can generally rise above 0℃, with less snow and more rain. However, in the warm climate of Sichuan Basin, even in the dead of winter, rainfall is not uncommon. During this period, the average climate temperature in our province is mostly above 10℃, peaches and plums are in bud, and cherries are in full bloom. It is indeed a climatic spring. In addition to a few years, the frost period has come to an end. It is timely to graft fruit trees and plant trees. After the dry winter, there are many droughts in spring all the year round, especially in the west of the basin. In agriculture, attention should be paid to moisture conservation and timely irrigation to meet the water supply at jointing and booting stage of wheat and at the critical stage of bolting and flowering of rape. The mountainous area of western Sichuan Plateau is still in the dry season, with low temperature and high wind speed, which is prone to forest fires. In addition, the invasion of cold wave will cause strong cooling and snowstorm, which will do great harm to the old, weak and young animals. These should pay special attention to prevention. Time flies and the seasons remind people. "A year's plan lies in spring". The management of Koharu and the preparations for Da Chun should be carried out quickly, so as to make this year better than previous years.

Awakening of Insects

Reflecting the awakening of natural phenology, it refers to the sudden movement of spring thunder, which awakens the animals dormant in the soil and hibernating. At this time, the temperature rose rapidly, and spring thunder gradually appeared in most areas of the Yangtze River Basin. In the eastern part of the basin of our province and the southern part of Liangshan Prefecture, the first sound of spring thunder can also be heard in the perennial rain and stormy waves; In the northwest of the basin, except for a few years, it usually doesn't thunder until Qingming, which is the latest area where thunderstorms begin in our province. By the time of the earthquake, most parts of China had entered the busy season of spring ploughing. Really: the season waits for no one, and every moment is worth a thousand dollars. The average temperature of the startled solar term in our province is generally 12℃ to 14℃, which is more than 3℃ higher than the rain solar term, and it is the solar term with the fastest annual warming. The sunshine time has also increased significantly. However, due to the alternation of cold and warm air, the weather is unstable and the temperature fluctuates greatly. In the Yangtze River basin in the southeast of the basin, the temperature in the warning period is stable above 65438 02℃ in most years, which is beneficial to the sowing of rice and corn. The average daily temperature in other areas is lower than 12℃ for more than three consecutive days, so it is not allowed to sow blindly early. Although the temperature rises rapidly, the increase of rainfall is limited. The total rainfall in the middle and northwest of the basin is only about 10 mm, and after years of winter drought, spring drought often begins to appear. At this time, the booting stage of wheat and flowering stage of rape are in a period of high water demand and are sensitive to water demand. Spring drought often becomes an important factor affecting the output of Koharu. Afforestation should also consider this climate feature, plant logistics and water, and strive to improve the survival rate of saplings. In the season of fright, the spring is bright and everything is revived. Through careful observation and accumulation of phenological knowledge, it will help to arrange farming activities according to local conditions.

Spring Equinox

The vernal equinox is one of the solar terms reflecting the changes of the four seasons. In ancient China, beginning of spring, Changxia, beginning of autumn and beginning of winter were used to indicate the beginning of the four seasons. The vernal equinox, summer solstice, autumn equinox and winter solstice are in the middle of each season. On the vernal equinox, the sun shines directly on the equator, and the time between day and night is equal all over the earth. Therefore, the ancient vernal equinox and autumnal equinox are also called "equinox", and there is a folk proverb that "vernal equinox and autumnal equinox are equally divided day and night". After the vernal equinox, the overwintering crops in most parts of China entered the spring growth stage. There is an agricultural proverb in Central China, "Wheat starts at the vernal equinox, and every moment is worth a thousand dollars". The temperature in all parts of our province continues to rise, but it is generally not as fast as the spring equinox. In late March, the average temperature in the north of the basin was mostly 13℃ to 15℃, and in the south of the basin was mostly 15℃ to 16℃. Most of the plateau has been melted by snow, and the ten-day average temperature is about 5℃ to 10℃. The temperature in the valley areas such as Jinsha River and Anning River in the southwest of our province is the highest, with an average of 18℃ to 20℃. Except in marginal mountainous areas, the average daily temperature in the basin has steadily increased to above 65438 02℃ in the past seven or eight years, which is beneficial to planting crops such as rice and corn, and is also very suitable for afforestation. However, before and after the vernal equinox, strong cold air often invades the basin, and the temperature drops obviously, and the lowest temperature can be as low as 5℃. Sometimes a small stream of cold air comes one after another, forming a low temperature and rainy weather that lasts for several days, which is not good for agricultural production. According to this feature, we should make full use of the weather forecast, grasp the cold tail and warm head, and sow in time.

Qingming Festival

Qingming is a solar term representing phenology, which means sunny weather and lush vegetation. Tomb-Sweeping Day has folk customs such as climbing mountains, eating cold food and sweeping graves. As the saying goes, "Qingming breaks snow, Grain Rain breaks frost." When the weather is clear, the climate in the basin is warm and the spring is strong. However, before and after Tomb-Sweeping Day, cold air still invaded from time to time, even making the average daily temperature lower than 12℃ for more than three consecutive days, resulting in rotten seedlings of middle rice and dead seedlings of early rice. Therefore, it is necessary to avoid warm tail and cold head when sowing and transplanting rice. In the western Sichuan Plateau, livestock are weak under the influence of severe winter and insufficient forage, so it is necessary to guard against the harm of strong cooling weather after spring to old, weak and young livestock. "There are many rains during the Qingming Festival" is a portrayal of the spring rain in the south of the Yangtze River by Du Mu, a famous poet in the Tang Dynasty. But as far as Sichuan is concerned, this is not the case. Especially in the west of the basin, it is often in the spring drought period, and the rainfall in early April is generally only 10 to 20 mm, which is less than half of that in the south of the Yangtze River. Although there are many spring rains in the eastern part of the basin, the rainfall in early April is generally only 20 to 40 mm, and the natural precipitation is not enough for agricultural production, so it must be replenished by storing water years ago. In addition, April is the month with the most hail in Liangshan Prefecture in a year, so the prevention of hail disaster should be strengthened.

Grain Rain

As the saying goes, "Rain gives birth to a hundred valleys". With sufficient and timely rainfall, cereal crops can thrive. Grain Rain solar terms have such a meaning. Grain Rain season, Sichuan Basin, "young flowers fall, cuckoos cry at night, peonies bloom, and cherries are ripe. The natural scenery tells people that it is late spring. At this time, the temperature in the basin rose rapidly. Generally, the average temperature in late April has reached 20℃ to 22℃, which is more than 2℃ higher than that in mid-April, except for the northern and western parts of the basin. In the eastern part of the basin, there is often a high temperature of more than 30 degrees for a day or two, which makes people feel very hot. The low-altitude valley area in southwest Sichuan is used for entering summer. The climatic characteristics of high temperature in spring in the basin are beneficial for Da Chun to take early measures. The suitable planting temperature of Polygonum cuspidatum is 65438 08℃ to 22℃, which can be satisfied at this time. Experience in the old arid area of the river basin proves that planting Osmunda japonica early after Grain Rain can seal vine leaves before summer drought, enhance drought resistance and obtain high and stable yield. At this time, the eastern part of the basin in our province is full of rain. The rainfall in late April of the year is about 30 to 50 mm. The first rainstorm usually occurs in this period, which is beneficial to rice planting and the growth of corn and cotton at seedling stage. However, the rainfall in most other areas of the basin is less than 30 mm, so irrigation measures should be taken to alleviate the impact of drought. The mountainous area of the western Sichuan Plateau is still in the dry season, and the precipitation is generally only 5 to 20 mm. The rainfall around Grain Rain in the basin often "sneaked into the night with the wind, and moistened things silently" because the frequency of "late rain" was the highest in April and May. It often rains at night in Sichuan, and the river sill is clear, which is very suitable for crop growth and harvest.

Early summer

As the name implies, long summer refers to the beginning of summer. However, the temperature varies from place to place, and the time of entering summer is actually inconsistent. According to the climatological standard that the five-day average temperature in summer is higher than 22℃, the southern Sichuan basin just entered summer before and after the long summer; The temperature in other basins is about 20℃, and it is still in the late spring season when "there is no one outside to ask the flowers to fall, and Ran Ran is covered with greenery all over the world"; The low-altitude valley in southwest Sichuan felt the heat of summer as early as mid-April, and the temperature in long summer has reached above 24℃, which can be described as hot summer. Yi Wei has a long summer's theory of "seeing with electricity" But as far as Sichuan is concerned, even in the northwest of the basin, where the first thunderstorm is the latest, the perennial thunderstorm begins in the middle of April, so it is not necessary to wait until the long summer. After the long summer, it is the critical period of water demand for large-scale cultivation of mid-season rice in the basin. The early and late arrival of rainstorm and the amount of rainfall are closely related to agricultural production. At this time, if there is no heavy rain, those farmland without water irrigation can't rake pears and sow seeds. According to the statistics of climate data, the average rainstorm for many years in the east of the basin began in the middle and late April and in the west in the middle and late May. The rainfall in the southeast of the basin in May is100-200mm, and that in the northwest is 75-100m. In the western and central parts of the basin, the rainstorm started late, with little rainfall, and summer drought often appeared. During this period, just like harvesting crops in early spring in the basin and planting crops in Da Chun, special attention should be paid to the influence of changeable weather. Harvest in time in sunny days and sow in rainy days. Even in rainy days, the harvest in Koharu should be protected from germination, mildew and drought, and the harm of low temperature below 20℃ to early rice should be prevented.

Grain Buds

Most of the 24 solar terms can be defined by their names, but Xiaoman is somewhat puzzling. Originally, Xiaoman means that summer crops such as wheat are full of milk and seeds. Agricultural proverbs in Sichuan basin give Xiaoman a new meaning: "Xiaoman is not satisfied, he thinks about it"; "Little people are full of discontent, regardless of mangoes." The word "full" is used to describe the amount of rain, and it is pointed out that if there is not enough water in the field when it is full, the ridge may crack and even rice cannot be planted when it is planted. Because "transplanting rice in long summer and planting rice in small fields" and "seedlings rushing into small fields in autumn", small fields are suitable for rice planting. The severity of summer drought in the basin is directly related to the rice planting area. Planting sooner or later is closely related to the yield of rice. In the central and western parts of the basin, there are often droughts in winter and spring, and heavy rains come late. In some years, the rainstorm didn't come until June, or even as late as July. In addition, the annual rainfall in the small solar term is not much, with an average of only about 40 mm, and the natural rainfall can not meet the water demand for planting seedlings, which makes the summer drought in the central part of the water-deficient basin more serious. As the saying goes, "storing water is like storing grain" and "preserving water is like storing grain". In order to resist drought, in addition to improving cultivation measures and speeding up afforestation, it is especially necessary to pay attention to water storage and moisture conservation in the first year. However, we should also pay attention to the possible continuous rainy weather, which will affect the harvest and drying of spring sowing crops. In the mountainous area of western Sichuan Plateau, at this time, many crops have entered the rainy season, and the crops are growing vigorously and thriving.

Grain in Ear

The awn seed is a symbol of the maturity of awned crops such as wheat and a solar term reflecting agricultural phenology. By the time of the awning, the wheat harvest season in Sichuan Basin has passed, and the transplanting of mid-season rice and sweet potato is coming to an end. In most areas, the mid-season rice has entered the green stage, and the seedlings are green and full of vitality. The poem "The east wind dyed 3,000 hectares, and the herons kept coming and going" vividly described the beautiful scenery of the field at this time. In the awning season, the medium rice that has not been transplanted in the basin should be planted quickly; If it is postponed again, the vegetative growth period of rice will be shortened due to the increase of temperature, and the growth period will be easily affected by drought and diseases and insect pests, and the yield will inevitably be low. Osmunda japonica should be transplanted before summer at the latest; If sowing is too late, not only the drought will worsen, but also the temperature will drop in Qiu Lai, which is not conducive to the expansion of potato chips and the yield will be significantly reduced. This is the truth of the agricultural proverb "busy planting".

Summer solstice

On the solstice of summer, the sun shines directly on the Tropic of Cancer, which is the longest day of the year in the northern hemisphere. It takes about fourteen hours from sunrise to sunset in all parts of Sichuan. Although the summer solstice has the longest day and the highest sun height, it is not the hottest time of the year. Because the heat in the near-surface layer is still accumulating at this time, and it has not reached its maximum. After the summer solstice, due to the vigorous growth of crops, the rapid growth and spread of weeds, pests and diseases, and the golden season of grass, fertilizer and livestock flourishing in plateau pastoral areas, agricultural production in our province has entered the field management period. At this time, the rainfall in the western part of the basin increased obviously, which gradually changed the distribution trend of rainfall in the basin from the east to the east since the spring. If there is a summer drought, it is generally expected to be lifted at this time. In recent 30 years, the number of large-scale floods in the western part of the basin in late June is small, but the degree is serious. Therefore, special attention should be paid to preparing for flood control. The solar term from summer solstice is the solar term with the largest annual rainfall in the eastern part of the basin, which is often controlled by subtropical high in the future, resulting in summer drought. In order to enhance drought resistance and win a bumper harvest in agriculture, it is an important measure to capture and store pre-dormant rainwater in these areas. 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 "dividing fields in summer and rain". In Sichuan, Liu Yuxi, a poet of the Tang Dynasty, skillfully used this weather to write a famous poem "Rising in the east and descending in the west, the road is sunny and sunny".

Minor Heat

Trees are shady and summer is hot. The average summer temperature in Sichuan Basin is about 26℃, which is already midsummer and quite hot, but it is not the hottest time yet. In mid-July, in the low-altitude valley area in the southeast of the basin, there may be a concentrated period in which the daily average temperature is higher than 30℃ and the daily maximum temperature is higher than 35℃, which is unfavorable for heading and flowering of hybrid rice. In addition to fully considering this factor in the layout in advance, corresponding remedial measures should be taken for those that have been planted. In the northern Sichuan Plateau, frost and snow can still be seen at this time, which is equivalent to the scene of early spring in the basin. Around the summer, the western part of the basin enters the season with the most rainstorm, and the number of rainstorm days in July and August can account for more than 75% of the whole year, usually about 3 days. Mountain torrents often occur in places with large relief, and even cause mudslides. However, in the eastern part of the basin, due to the frequent control of subtropical high, the weather is sunny and hot, and after experiencing a slight summer heat, it began to enter the summer drought period. The climatic characteristics of the waterlogging in the east and west of this basin in our province are closely related to the abundance and shortage of agriculture. We must take drought and flood control measures as soon as possible to minimize the harm. Around the summer heat, all parts of our province entered the season with the most thunderstorms. Thunderstorm is a disastrous weather phenomenon, often accompanied by strong winds, heavy rain and sometimes hail, which is easy to cause disasters and must be prevented.

Major Heat

Hot in summer means hot. Explanation is the hottest solar term in a year. Generally speaking, the summer solar term is the period with the most sunshine and the highest temperature in a year in the basin, the period with the most abundant rainfall, the most common thunderstorm and the most concentrated high temperature days above 30℃ in the west of the basin, and the period with the most frequent high temperature above 35℃ in the east of the basin. The high temperature around summer is a sign of normal climate, because in Da Chun, higher temperature is beneficial to the flowering and filling of crops. However, if the temperature is too high, it will inhibit the growth of crops and the seed setting rate of rice will decrease obviously. After the western part of the basin was flooded, light, heat and water were at the peak of a year, which promoted each other and formed good climatic conditions for crop growth in Da Chun, but attention should be paid to flood control and drainage. In the eastern part of the basin, high temperature and long sunshine are often accompanied by little rain, which will not only limit the exertion of light and heat advantages, but also aggravate the adverse effects of drought on crops in spring and summer. In order to resist summer drought, we should not only pay attention to early water storage, but also improve crop cultivation measures based on "early" according to the climatic characteristics in the eastern part of the basin, so as to achieve advantages and avoid disadvantages. The sultry summer is the season when jasmine and lotus are in full bloom. The more fragrant jasmine is, the more fragrant it is, giving people a clean and fragrant enjoyment. Noble lotus flowers, not afraid of the hot sun and showers, gather in the morning and evening. The poet praised it as "reflecting the different colors of lotus flowers in the sun", and the vibrant midsummer is gestating a bumper harvest.

Beginning of Autumn

"It's cool on beginning of autumn Day" obviously associates beginning of autumn with cool weather. It can be seen that beginning of autumn is the beginning of cool autumn. Because of the different latitudes and altitudes, it is practically impossible to enter autumn at the same time in beginning of autumn. According to the climatological standard that the five-day average temperature is between 10℃ and 22℃, in China, except those places with high altitude in north latitude, beginning of autumn is still in hot summer, and even in most parts of Northeast China, there is no autumn scenery with cool breeze and yellow leaves fluttering. For the Sichuan Basin located in the middle subtropical zone, the summer heat is still heavy in August all the year round. Statistics of climate data show that the basin will not enter autumn until the middle and late September. It is impossible to say when autumn begins in the plateau mountainous area where winter is all the year round or winter is long without summer, and spring and autumn are connected. After beginning of autumn, at the jointing and booting stage of late rice in our basin, cotton bolls cracked and vomited, which could not relax field management at all; Mid-season rice and summer corn enter the stage of filling maturity, so it is necessary to guard against the harm of hail, strong wind and heavy rain. The eastern and western parts of the basin should continue to do a good job in drought and flood control respectively. In the basin behind beginning of autumn, although the season is still midsummer, "beginning of autumn is full of yellow in ten days" and a golden "autumn" is coming.

The heat is over

Summer is a solar term reflecting the temperature change. "Chu" means to hide and die, and "early summer" means that the hot summer has passed. The average temperature in our basin is generally about 65438 0.5℃ lower than that in early autumn. In late August of some years, the average daily temperature in the west of the basin may be lower than 23℃ for more than three consecutive days, which will affect the flowering of hybrid rice. However, because the summer heat in the basin is still basically controlled by the summer monsoon, the highest temperature in the west of the basin is often higher than 30℃, and the highest temperature in the east of the basin is higher than 35℃. Especially in the low-altitude areas along the Yangtze River, in the year when the summer drought lasted, the "autumn tiger" was felt. The western Sichuan Plateau has entered the summer and autumn season, with an altitude of more than 3,500 meters, showing the scene of early winter, withered grass and increasing frost and snow. Summer is the early stage of the transformation of rainfall distribution in our province from more in the west to less in the east. At this time, the rainfall in the central part of the basin is often the second highest in a year, which is more than that in hot summer or white dew. Therefore, in order to ensure farmland water use in winter and spring, we must do a good job of water storage in this period. There will be continuous rainy weather in the plateau from summer to autumnal equinox, which is not good for agriculture and animal husbandry production. At this time, our basin is also a busy season for harvesting mid-season rice. Generally, during the summer solar term, the sunshine in the basin is still sufficient, except for the western part of the basin, there are not many rainy days, which is beneficial to the middle rice cutting and cotton bolling. But in a few years, as Du Fu said in his poem, "The dog days have passed and the sun has turned into rain", the autumn rain will come early. Therefore, we should pay special attention to the weather forecast, make full preparations, seize every sunny day, seize the opportunity, and do a good job of grabbing a bumper harvest and basking in the sun.

White Dew

Dew is water droplets formed by condensation of water vapor on the ground or near-earth objects due to temperature drop. So the Millennium actually indicates that the weather is getting cold. In the climate of 24 solar terms in the basin of our province, the White Dew has the obvious characteristics of rapid temperature drop, the beginning of rain in Mao Mao and the sudden decrease of sunshine, which profoundly reflects the seasonal changes from summer to autumn. The average temperature of the basin in the perennial white dew period is about 3℃ lower than that in summer, and the average temperature in most areas (5 days) has been continuously reduced to below 22℃. According to the standard of dividing four seasons by climatology, the time series begins to enter autumn. Autumn rain in the basin mostly occurs from the white dew to the first frost, with the most in the middle and lower reaches of Minjiang River and Qingyi River, and relatively less in the middle of the basin. The agricultural proverb "There are too many white dew, walking around every day" can't predict the weather by whether it rains on the day of the white dew, but there will always be a period of continuous rainy weather before and after the white dew festival. Moreover, since then, rainfall in the basin has been characterized by low intensity, frequent rainy days and continuous rainfall. Accordingly, the sunshine in the basin during the white dew period is about half that in summer, and the decreasing trend continues until winter. The above-mentioned climatic characteristics of the Millennium season are not conducive to heading and flowering of late rice, but also affect the harvesting and sunning of middle rice, so there is a saying in agricultural proverbs that "the Millennium is sunny and the rice is as white as silver". Only by fully understanding the Millennium climate characteristics and taking corresponding agricultural technical measures can the harm of autumn rain be alleviated or avoided. On the other hand, we should also seize the rainwater to store water, especially the Bailu in the east of the basin is another solar term with more rainfall after Xiaoman and summer solstice. Don't miss the good opportunity.

Autumn Equinox

The autumnal equinox is a solar term representing seasonal changes. On the day of the autumnal equinox, the sun is located at longitude 180 degrees, and the sunlight is almost direct to the equator, and day and night are almost equal. At this time, the waiting temperature in Sichuan basin generally dropped below 22℃, and it entered a cool autumn. "An autumn rain and a cold". The cold air from the south meets the warm and humid air that gradually decays, which leads to repeated rainfall and the temperature drops again and again. In the northern part of the western Sichuan Plateau, the daily minimum temperature has dropped below 0℃, and you can already see the magnificent snow scene flying all over the sky and the earth wrapped in silver. After the autumnal equinox, the rainfall in our province is obviously reduced, and heavy rain and heavy rain generally rarely appear; However, rainy days increase, rainy days are frequent, and the night rain rate is high. Li Shangyin, a famous poet in the Tang Dynasty, famously said, "It rains late in autumn pond", which vividly describes the climate characteristics of rainy nights in autumn in Sichuan. It is rainy in autumn in the basin of our province and Liangshan Prefecture, and the wet damage is serious, which has a great influence on autumn harvest, autumn ploughing and autumn planting. It is necessary to grasp the sun, control soil moisture and prevent waterlogging, and do a good job in the quality and progress of Sanqiu production. At the same time, we should make full use of the meteorological conditions of rainy autumn and good soil moisture, seize the opportunity to do a good job in afforestation, and strive to improve the survival rate of saplings.

Cold Dew

In ancient times, dew was considered as a sign that the weather turned cold. The solar term of the Mid-Autumn White Dew is "dew condensation and white". It is cold in season and autumn, and it is already "dew gas is cold and will condense" into frost. At this time, the temperature in all parts of our province continued to drop. The average daily temperature in the basin is below 20℃. Even in the areas along the Yangtze River, it is difficult for the mercury column to rise above 30℃, while the minimum temperature can be reduced to below 10℃. Except for a few valley lowlands, the five-day average temperature in the western Sichuan Plateau is generally lower than 10℃, which is winter according to the standard of four seasons climate division. The frost and snow in Wan Li are quite different from the autumn colors in the basin. During the perennial cold dew, the rainfall in the basin is also decreasing day by day. Most of the western part of the basin is about 20 mm, and the eastern part is generally about 30-40 mm. It rains frequently, day and night, which affects the emergence of "Sanqiu" and becomes a disastrous weather in our basin. The climatic characteristics associated with the rain in Mao Mao are: high humidity, more clouds, less sunshine and more cloudy days, and the number of foggy days has obviously increased since then. However, whether the autumn rain seriously affects the progress and quality of "Sanqiu" directly. To this end, on the one hand, we should use the weather forecast to harvest and sow in sunny days; On the other hand, according to local conditions, we should take various effective farming measures such as deep ditch and high compartment to reduce wet damage and improve sowing quality. In the plateau area, before and after the cold dew is one of the most serious seasons of snow damage. Snow jams traffic and harms animal husbandry production, so we should pay attention to prevention.

Frost's Descent

The solar term of the first frost means that the weather is getting colder and first frost begins. In the south latitude Sichuan Basin, the average temperature is about 65438 06℃, and there are three solar terms before the first frost day. In the southern valley of the basin, frost can only be seen in the dead of winter. Of course, even at the same latitude, the temperature and humidity of the air close to the stratum are different due to the difference of altitude and topography, and the first frost period and frost day are also different. From a scientific point of view, the saying that "dew becomes frost" is not accurate. The frozen dew formed by dew freezing is hard small ice beads. Frost refers to the phenomenon of crop freezing injury caused by the sudden drop of temperature, and its harmful temperature varies with crops, varieties and growth periods. To form frost, the temperature of the ground or ground objects must drop below 0℃, and the water vapor content in the air on the ground should reach a certain level. Therefore, there may not be frost in first frost, and there may not be frost in first frost. However, due to the low temperature during frost, if the temperature continues to drop, it will easily lead to frost. After the first frost, a large number of Dioscorea zingiberensis were collected and excavated in our basin. If the harvest is too early, the lump will not fully expand, which will affect the yield; But if the harvest is too late, it may be damaged by early frost, and the block will be frozen and deteriorated, so it is very important to dig it out in time. Su Shi, a great writer in the Northern Song Dynasty, said in a poem: "There are thousands of trees to eliminate pornography, and only Furong is alone." The climate in Sichuan Basin is mild. During the first frost, the fields are lush, orange-yellow-orange-green, autumn chrysanthemums are in full bloom, and hibiscus trees are in full bloom, making the rich "Tianfu" even more gorgeous.

Beginning of Winter

Speaking of "winter", it will naturally be associated with cold. "Stand and build" means that winter begins from now on. On that day in beginning of winter, the water began to freeze and the ground began to freeze. Nowadays, people often regard the biting north wind and cold frost and snow as symbols of winter. Rare frost and snow in our basin. Therefore, in climatology, beginning of winter is not fixed as beginning of winter, but the seasons are divided by temperature, that is, the five-day average temperature is lower than 10℃ as winter, which is more suitable for the phenological landscape at that time. In early winter, this basin is still in the peak season in Sanqiu, and the average temperature is generally between 65438 02℃ and 65438 05℃. The rain has passed in Mao Mao. Climatic conditions are suitable for rape transplanting. Wheat with short growth period and strong elasticity should also be sown, because there are many strong cold air attacks in the later period of beginning of winter, and the temperature often drops greatly. If the temperature after sowing is low and the seedling emergence is slow, the yield will be affected. When the daily average temperature is lower than 15℃, the growth of Osmunda japonica has gradually stopped and should be harvested in time. Early frost has appeared in early winter in some years in the northwest of the basin. In order to avoid freezing injury, the pit should be dug as soon as possible. At this time, the plateau area is already in the dry season, the humidity is rapidly decreasing, and the wind speed is gradually increasing, so we must be highly alert to forest fires.

Minor Snow

Light snow indicates the beginning time and degree of snowfall. Snow is the product of cold weather. Light snow solar terms, the northern Sichuan Basin began to enter winter. "There is no rain in the lotus, but there are frost branches in the chrysanthemum", which has already shown the scene of early winter. Because there are barriers at the northern foot of Qinling Mountain and Daba Mountain to block the invasion of cold air and reduce the severity of cold wave, the basin is "warm in winter and cool in summer". The number of snowfall days in the whole year is mostly less than 5 days, which is much less than that in the middle and lower reaches of the Yangtze River at the same latitude. There is little chance of snowfall before the heavy snow. Even in the middle of winter, you can rarely see the charming scenery of "blowing open the petals of ten thousand pear trees". Because the surface temperature of the basin is often above 0℃ in winter, it is more difficult to snow than to snow. Occasionally, although the sky is buzzing, there is no "broken jade" on the ground. In the cold western Sichuan Plateau, snow usually starts at 65438+ 10 all year round. The number of snowfall days in the northwest of the plateau can reach more than 60 days a year, and snowfall is possible in some alpine regions all year round. During the light snow, the first frost can be seen in the northwest of the basin, so it is necessary to guard against the harm of frost to crops. The lowest temperature in Gansu and northern Afghanistan is around-15℃, so it is necessary to keep livestock warm and cold.

Major Snow

"Heavy snow" means that it begins to snow at this time. The winter climate in Sichuan Basin is mild, with little rain and snow. The average temperature is about 2℃ to 4℃ higher than that in the middle and lower reaches of the Yangtze River, and the rainfall accounts for only about 5% of the whole year. Occasionally it snows, mostly in 1 and February; Snow on the ground is hard to see once every three to five years. It is often an unforgettable pleasure to witness the snow-covered earth and the green trees wrapped in silver. "Xue Rui heralds a bumper harvest year" is an agricultural proverb widely circulated in China. In the north, a thick layer of loose snow is like covering wheat with a quilt to keep out the cold. The content of nitrogen compounds in snow is four times that of rain. Snow slowly melts and penetrates into the soil, which can increase the nitrogen in the soil and be easily absorbed and utilized by crops. The low temperature of snow water can freeze the overwintering pests on the surface and bring benefits to agricultural production. However, in the south, if the ground heat loses a lot on a sunny night after snow, there will be freezing damage, which will cause certain losses to crops such as peas and beans. The average temperature in our basin is still 8℃ to 9℃, and wheat and rape can still grow slowly, so it is necessary to strengthen field management to prevent freezing injury. During the heavy snow, the precipitation in the basin is mostly below 15 mm, and the western part of the basin is less than 5 mm, which is already a "dry winter" period. At this time, the climate of the basin is still foggy. Generally, 65438+February is the month with the most foggy days. Fog usually appears on cloudless nights or partly cloudy mornings. Meteorology calls it radiation fog. As the saying goes, "ten fogs and nine sunny days". Most of the fog will dissipate before noon, and the sunshine in the afternoon will be particularly warm.

Winter solstice

Winter solstice is a solar term divided by astronomy, which was called "short day" and "short day" in ancient times. From winter to the sun, the sun is located at 270 degrees of the Yellow Meridian, and the sun shines almost directly to the Tropic of Capricorn, which has the shortest day in the northern hemisphere. There is no 10 hour from sunrise to sunset in all parts of our province. From winter to the future, as the earth orbits the sun, the direct sunlight belt gradually moves northward, making the days in the northern hemisphere gradually longer and the nights gradually shorter. In winter solstice, although the height of the sun is the lowest, the sunshine time is the shortest, and the heat absorbed by the ground is less than the heat lost, the heat accumulated on the ground for a long time continues to be lost, and the temperature near the ground layer has not dropped to the lowest, so it is not the coldest time of the year. After the winter solstice, although the days are getting longer and shorter, the days are getting shorter and shorter, and the nights are getting longer and longer in the short term. The heat absorbed by the ground every day is still less than the heat lost, so the temperature did not rise immediately. The masses are used to counting nine from the solstice in winter, and every nine days is a "nine". Before and after "March 9th", the area was the least hot and the weather was the coldest, so it was said that "March 9th was cold". Astronomy regards the winter solstice as the beginning of winter, which is obviously late for most parts of China. During the winter solstice, the average temperature in the western Sichuan Plateau is generally below 0℃, while the average temperature in the Sichuan Basin is only about 6℃ to 8℃. In the low-altitude valley area of southwest Sichuan, even in the coldest local165438+ in early October, the average temperature is still above 10℃, so it can be said that autumn comes and spring comes, and there is no winter all year round.