Today, we usher
The last of the twenty-four solar terms
【Big Cold】
Spring aquatic in the depths of solid ice
The great cold means the end of the four hours
It also heralds the beginning of the new year
Today, the Chinese Teacher Invited 10 Teachers,
Use the knowledge of various subjects to talk about the big cold,
Let's get a boost in knowledge together
Chinese teacher
Students, do you know how the literati of ancient times wrote about Da Han? Today we will taste and read these poems related to the great cold -
"The Great Han Yin"
【Song Dynasty】 Shao Yong
The old snow has not yet subsided, and the new snow has been crowded.
Frozen silver bed in front of the steps, ice stalactites at the eaves.
The sun is shining, and the wind is raging.
The population has its own tongue, and the words cannot be spit out.
Cold language: The old snow in front of the door has not yet melted, and the new snowflakes have swept in, what a cold word!
"Years of Cold Knowledge Pine Cypress"
【Song Dynasty】 Huang Tingjian
Pine cypress is born unique, green through the four hours.
After the heart is hidden, there is a great cold knowledge.
Bleak frost night, wheels and streams.
Or to accommodate the ant nest, not to see the axe late.
Shake the thousand autumns and be quiet, and be sad.
Zheng Gongfu Zhenguan was no longer seen.
Cold language: Pine and cypress are evergreen in all seasons, cold seasons, ice and snow, it is necessary to focus on winter recuperation and maintain spiritual tranquility.
"You Ciyun"
[Song Dynasty] Chen
The old man is not more in tune with the world, so he says that idleness is thriving.
Slightly wet and easy to dry sand soft road, cold but warm snow sunny days.
I have never been to the temple, and I have used the plum mountain to find myself.
Laughing asked matsube people Tsurushi, Ru knows what year it is today.
Cold language: A rare encounter with great cold and warmth, the aroma of Ciyun Temple has already wafted in, and I suddenly do not know what year it is.
"Bitter Cold Chant"
【Tang Dynasty】Mengjiao
The sky is cold and green, and the north wind is called dry mulberry.
Thick ice without cracks, short days with cold light.
Knocking stones must not be fired, and the strong yin is seizing the sun.
Tune the bitterness and say nothing, and freeze into this chapter.
Cold language: the sky is cold, the north wind is whistling, the ice surface is solid, the daylight is cold, so cold.
Math teacher
Students, everyone knows that the time of the great cold is around January 20 of the solar calendar, but do you know how the date of the great cold is calculated? come! Above formula ——
Calculation formula: [Y*D+C]-L
Interpretation of the formula: Y = the last 2 digits of the number of years, D = 0.2422, L = leap years, 21st century C = 20.12, 20th century C = 20.84.
For example, the 2021 Winter Day = [21×0.2422 + 20.12] - [(21-1)/4] = 25-5 = 20, January 20, 2049 Cold Date = [49×0.2422 + 20.12] - [(49-1)/4⌋] = 31-12 = 19, January 19.
English teacher
Students, today is the last of the twenty-four solar terms of the lunar calendar - "Great Cold".
Major cold - The last of the 24 traditional Chinese solar terms.
The arrival of the great cold is also the time to welcome the Spring Festival. People are busy buying new things, making cured meats, and preparing new year goods. "Great Cold" represents the end of the 24 solar terms, which also means the end of winter.
When this day arrives, it’s time to welcome the Spring Festival. People get busy with buying new things, salting the meat and preparing New Year good. “Major Cold” represents the end of 24 solar terms and also marks the end of winter.
Political teacher
The great cold is the last and coldest festival of the year, and the folk proverb has clouds, "the great cold reaches its peak, and the day warms up later." ”
Winter is almost over, will spring be far away? Chinese summed up from ancient philosophy the philosophy of life that "things must be reversed, and no poles must come", which embodies the truth that the two sides of the contradiction are transformed into each other under certain conditions. Now people also like to say "bottoming out", if you are now at the bottom of life, don't be anxious, endure it again, the willow is in front of you.
The cycle of twenty-four solar terms, and so on, embodies the alternating transformation of qualitative change and quantitative change, and also reflects the truth that people give full play to their subjective initiative and understand objective laws.
History teacher
According to the "Three Rites and Righteous Sects" quoted in the "Time-Granting Tongkao Tianshi", "The great cold is the middle, and the upper form is in the small cold, so it is called great... The reverse pole of the cold is called the great cold. ”
There are three seasons for the great cold
Wait for | Chicken milk
On the day of the great cold, "chicken milk", chickens are wooden animals,
Sensing the spring breeze in advance,
Start hatching the chicks;
Second waiting for | Birds are fierce
Birds such as falcons,
In a state of extreme predatory ability,
In search of food to replenish energy against the cold;
Three waits for | Mizusawa belly is strong
In the last five days of the year,
The ice in the waters freezes all the way to the center of the water,
And the strongest, thickest.
In addition, the ancients have another saying about the "three weathers" of flowers---- one waiting for Ruixiang, two waiting orchids, and three waiting mountain alum (growing in the Jiangnan area), can also be used as an important symbol of the great cold.
Geography teacher
Every year around January 20, when the sun reaches 300° ecliptic longitude, it is a great cold.
At this time, the cold wave is frequent in the south, which is the cold period of the year in most parts of china, with strong winds, low temperatures, and snow on the ground, showing a cold scene of ice and snow, cold and frozen.
As the saying goes: "Flowers and trees are seasonal, birdsong is reported to the farm". Flowers, trees, birds and birds are all active according to the seasons, so their regular movements are regarded as an important symbol of distinguishing seasonal seasons.
The ancients believed that the Great Cold was the coldest time of the year. Some students wondered, during the winter solstice, the sun is the farthest away from the northern hemisphere at the point of direct sunlight, why not the coldest at the winter solstice? The reason is that the winter solstice is the day when the northern hemisphere absorbs the lowest amount of solar energy, but the surface heat storage takes time to release, so the temperature is reduced to the minimum until around the time of the great cold.
Physics teacher
Students, we have all heard a proverb: "small frozen soil, big frozen river", what is the physical process of freezing on the river? Is it okay to drop the temperature to 0°C? Not really.
When the temperature drops to 0 °C, the water turns into ice. But the reality is not so simple. On the one hand, the water in nature is not pure water, which dissolves a lot of substances, the freezing point of the water is reduced, and the water needs to be frozen below 0 ° C; on the other hand, when the temperature is just below zero degrees to 0 ° C, the water will not freeze, because the latent heat released when freezing is very large, if it is exactly the freezing point, the newly generated ice crystals will melt away quickly. Generally, the temperature of the river is below zero degrees Celsius before the phenomenon of freezing occurs.
Still water ice requires a lower temperature, and the laboratory has recorded that the temperature of distilled water has dropped to -20 ° C and no ice crystals have been seen. Generally, after the still water is cooled to 4 ° C, the water surface continues to cool, which can only cool the surface layer, and the bottom layer is still maintained at a temperature of 4 ° C for a long time.
There are two cases of river freezing: one is to start from the shore, first form the shore ice, develop to the center of the river, and gradually merge into an ice bridge, and the width of the ice bridge expands, so that the entire river surface is frozen. There is also a type of drift ice that forms an ice dam in a narrow river or shoal, and the ice freezes rapidly with each other and between the ice cubes and the river bank, and expands upwards against the current, freezing the entire river surface.
Curious students can take the time to observe it!
Chemistry teacher
It's the cold season again, and the Spring Festival is about to usher in! You must be tempted to set off fireworks and firecrackers, right? So what are the main ingredients of firecrackers? When fireworks explode in the air, why do they bloom with colorful sparks? Do you know?
The main ingredient of firecrackers is black powder, which contains sulfur, charcoal powder, potassium nitrate, and some also contain potassium chlorate. When making fireworks, it is made by adding magnesium, aluminum, antimony and other metal powders to gunpowder in a certain proportion, as well as strontium, barium, sodium and other metal compounds. Since different metals and metal ions take on different colors when burned, fireworks explode in the air and produce colorful sparks.
For example:
Aluminum-magnesium alloy emits a dazzling white light when burned;
Strontium nitrate and lithium emit a red light when burned;
Sodium nitrate emits a yellow glow when burned;
Barium nitrate emits a green glow when burned.
......
These are the secrets of fireworks, which chemically call "flame reactions."
Biology teacher
Teacher Zhong
There is a "Bergmann's rule" about the cold adaptation characteristics of organisms: the law of biological appearance in the cold zone is to reduce the ratio of surface area to volume as much as possible, thereby reducing the rate of heat loss. According to this law, any slender structure of the body is not conducive to adaptation to the cold climate.
In contrast, people in the tropics have relatively long hands and feet, longer limbs (especially distal limbs), and relatively short trunks, and tropical animals also have this tendency, which are anatomical features that are conducive to heat dissipation.
Now you know what body is more suitable for extremely cold weather! It seems that the big long legs have also become "vases" in extreme cold!
Pedi teacher
A new round of solar terms is about to begin, the footsteps of the 2022 Beijing Winter Olympics are getting closer and closer, and ice and snow sports are also occupying an increasingly important position in the lives of Chinese people. Ice and snow sports are full of infinite charm, participating in ice and snow sports can strengthen the body, temper the will, have a positive and optimistic attitude, form a brave and strong character and a spirit of hard work and enterprising. Students, I believe that you will be able to get happiness in ice and snow sports.
Warm-up activities before winter sports can not be less. Warm-up must be done fully in place, otherwise it is likely that because of the low temperature, the stretchability of the human muscles is reduced, the joints are relatively stiff, and muscle strains and joint sprains are caused.
Also pay attention to the thickness of sportswear. Clothes should not be too tight or too thick, and do not wear a mask. Winter exercise wear clothes should be light and soft, not too tight, you can start to wear more, warm up until the body is hot and begin to sweat, and then take off excess clothes.
Whenever the exercise is over, the body needs to change from a state of motion to a relatively static state, which requires cold body exercise. It is as important as warming up and is an indispensable part of the post-exercise period. Winter is the season of accumulation of collection,
In the coldest hour of the year,
May you all have a good rest,
Have a happy and healthy year,
Build up for the new year!
Content Source | Xinhua Net, Central Committee of the Communist Youth League, National Campus Football and Physical Health Arts Official, Poetry World, Wenhui Education, etc
Source: China Education News
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