There is little scientific knowledge about snow.

The precipitation that falls on the earth's surface in the form of solid in the atmosphere is called atmospheric solid precipitation.

Snow is one of the most extensive, universal and main forms of atmospheric solid precipitation. There are many kinds of atmospheric solid precipitation, including beautiful snowflakes, hail that can cause great harm, and snow graupel and ice particles that we don't often see.

Snowflakes form in the sky. How does water vapor in air movement form snowfall? Is the temperature below zero enough? No, if water vapor wants to crystallize, there must be two conditions to form snowfall: one condition is that water vapor is saturated. The maximum amount of water vapor that air can hold at a certain temperature is called saturated water vapor.

The temperature at which air reaches saturation is called dew point. When saturated air is cooled to a temperature below the dew point, the excess water vapor in the air becomes water droplets or ice crystals.

Because the saturated water vapor content of ice surface is lower than that of water surface, the water vapor saturation required for the growth of ice crystals is lower than that of water droplets. That is to say, water droplets can grow only when the relative humidity (relative humidity refers to the ratio of the actual vapor pressure in air to the saturated vapor pressure of air at the same temperature) is not less than 100%; As for ice crystals, they tend to grow when the relative humidity is less than 100%.

For example, when the temperature is -20℃ and the relative humidity is only 80%, ice crystals can grow. The lower the temperature, the less humidity is needed for the growth of ice crystals.

Therefore, in the high-altitude and low-temperature environment, ice crystals are more likely to be produced than water droplets. Another condition is that there must be condensation nuclei in the air.

Some people have done experiments, if there is no condensation nucleus, the water vapor in the air will only condense into water droplets if it is supersaturated to a relative humidity of more than 500%. But such a large supersaturation phenomenon will not exist in the natural atmosphere.

So without condensation nuclei, it is difficult for us to see rain and snow on the earth. Condensation nuclei are tiny solid particles suspended in the air.

The ideal condensation nuclei are those particles that absorb the most water. Such as sea salt, sulfuric acid, nitrogen and other chemicals.

So we sometimes see clouds in the sky, but there is no snow. In this case, people often use artificial snowfall. Snowflakes that don't condense in the sky all fall from the sky. How can there be non-condensing snowflakes in the sky? 1in the winter of 773, a newspaper in Petersburg, Russia reported a very interesting news.

According to news reports, at a dance, due to the large number of people and the burning of hundreds of candles, the ballroom was hot and stuffy, and the ladies and gentlemen in poor health almost fainted in front of the God of Joy. At this time, a young man jumped on the windowsill and smashed the glass with one punch.

As a result, an unexpected miracle appeared in the ballroom. Beautiful snowflakes danced in the hall with the cold airflow outside the window and fell on the hair and hands of people who were dizzy with heat. Someone rushed out of the ballroom curiously to see if it was snowing outside.

Surprisingly, the sky is dotted with stars and the crescent moon is as silver as water. So, where did the snowflakes in the hall come from? This is really a puzzling question.

Is anyone playing any magic tricks? But no matter how clever a magician is, he can't play with snowflakes in the hall. Later, scientists solved the mystery.

It turns out that the breath of many people in the ballroom is full of water vapor, and the burning of candles has scattered many condensation nuclei. When the cold air outside the window breaks through the window, it forces the saturated water vapor in the hall to condense and crystallize immediately and turn into snowflakes.

So as long as it snows, it will snow in the house. The basic shape of snowflakes is beautiful when it snows, but scientists and artists appreciate the exquisite snowflake patterns.

Glaciologists began to describe the shape of snowflakes in detail more than a hundred years ago. Ding Duoer, the originator of western glaciology, described the snowflakes he saw on Luoza Peak in his classic glaciology works: "These snowflakes ... are all composed of small ice flowers, each of which has six petals, some of which release beautiful little lateral tongues like Su Hua, some are round, some are arrow-shaped, or zigzag, some are complete, and some are lattice-shaped, but they are not beyond.

In China, as early as 100 BC in the era of Emperor Wendi of the Western Han Dynasty, there was a poet named Han Ying who wrote a biography of Han Poetry, which clearly pointed out that "there are six snowflakes everywhere." The basic shape of snowflakes is hexagonal, but there are almost no two identical snowflakes in nature, just as there are no two identical people on earth.

Many scholars have observed thousands of snowflakes with microscopes. These studies finally show that it is impossible to form snowflakes with the same shape and size and partial symmetry in nature. Among these observed snowflakes, even the regularly symmetrical snowflakes are deformed.

Why do snowflakes deform? Because the water vapor content in the atmosphere around snowflakes can't be the same in all directions, as long as there is a slight difference, the side with more water vapor content always grows fast. There are many collectors of snowflake patterns in the world. They collect all kinds of snowflake photos like stamp collectors.

An American named Bentley took nearly 6,000 photos in his life. Soviet photographer Siger Mountain is also a photographer of snowflake photos. His charming works are often used as models of structural patterns by artists.

Japanese Nakatani Yoshijiro and his colleagues worked hard for 20 years, shooting and studying thousands of snowflakes in the cold room of the laboratory of Hokkaido University in Japan and in the tent on the snowfield in northern Japan. However, although snowflakes have various shapes, they remain unchanged, so scientists may classify them into the above seven shapes.

Among these seven shapes, hexagonal snowflake and hexagonal prism snowflake are the most basic forms of snowflake, and the other five are only the development, transformation or combination of these two basic forms. The influence of snow on human health In winter, it snows heavily and endlessly.

People often ignore the role of snow when watching Yushu Qionghua. Snow has many benefits to human health.

Compendium of Materia Medica has long recorded that snow water can detoxify and cure the plague. Folk use snow water to treat burns.

2. the scientific knowledge about snow is urgent ~ experts help, high reward.

Snow water is the foundation of all kinds of life on the earth, and its changes and movements have created our world today.

On the earth, water is constantly circulating. The water in the ocean and on the ground is heated and evaporated into the sky. The water vapor moves to other places with the wind. When they encounter cold air, they form precipitation and return to the earth's surface. There are two kinds of precipitation: one is liquid precipitation, which is rain; The other is solid precipitation, which is snow or hail.

The precipitation that falls on the earth's surface in the form of solid in the atmosphere is called atmospheric solid precipitation. Snow is one of the most important forms of atmospheric solid precipitation.

In winter, precipitation in many areas of our country appears in the form of snow. Because the size, shape and density of the snow falling on the ground are different.

Therefore, the level of meteorological snowfall is measured by the water after the snow melts. Meteorologically, snow is generally divided into four grades according to the precipitation within 24 hours: 0. 1-2.4 mm snow is called light snow; 2.5-4.9 mm snow is called medium snow; 5.0-9.9 mm snow is called heavy snow; 10mm (including10mm) snow is called blizzard.

Judging from the precipitation, even the magnitude of blizzard is only equivalent to moderate rain in rainfall. It is roughly estimated that snow with a depth of 10 mm can only melt into water with a depth of10 mm. ..

Supplement: There are many kinds of atmospheric solid precipitation, including hail, sleet and ice particles that can cause great harm. Due to the difference of meteorological conditions and growth environment in the sky, solid precipitation in the atmosphere is caused.

The names of these atmospheric solid precipitation vary from place to place, from person to person, varied and extremely inconsistent. For convenience, the International Ice and Snow Committee under the International Hydrological Association held a special international conference in 1949 on the basis of consulting experts from various countries, at which the proposal of "Concise Classification of Atmospheric Solid Precipitation" was adopted.

This concise classification divides atmospheric solid precipitation into ten types: snowflake, star snowflake, columnar snowflake, needle snowflake, multi-branch snowflake, axial snowflake, irregular snowflake, graupel, ice particle and hail. The first seven kinds are collectively called snow.

Why can't the last three be called snow? It turns out that there are two processes for gaseous water vapor to become solid water. One is that water vapor first becomes water, and then water condenses into ice crystals. Another is that water vapor directly becomes ice crystals without water. This process is called water condensation. Therefore, snow is solid precipitation formed by condensation of water vapor in the sky.

The basic shape of snowflakes is beautiful when it snows, but scientists and artists appreciate the exquisite snowflake patterns. Glaciologists began to describe the shape of snowflakes in detail more than a hundred years ago.

Ding Duoer, the originator of western glaciology, described the snowflakes he saw on Luoza Peak in his classic glaciology works: "These snowflakes ... are all composed of small ice flowers, each of which has six petals, some of which release beautiful little lateral tongues like Su Hua, some are round, some are arrow-shaped, or zigzag, some are complete, and some are lattice-shaped, but they are not beyond. In China, as early as 100 BC in the era of Emperor Wendi of the Western Han Dynasty, there was a poet named Han Ying, who wrote a biography of Han Poetry, which clearly pointed out that "there are six snowflakes everywhere. "

The basic shape of snowflakes is hexagonal, but there are almost no two identical snowflakes in nature, just as there are no two identical people on earth. Many scholars have observed thousands of snowflakes with microscopes. These studies finally show that it is impossible to form snowflakes with the same shape and size and partial symmetry in nature.

Among these observed snowflakes, even the regularly symmetrical snowflakes are deformed. Why do snowflakes deform? Because the water vapor content in the atmosphere around snowflakes can't be the same in all directions, as long as there is a slight difference, the side with more water vapor content always grows fast.

There are many collectors of snowflake patterns in the world. They collect all kinds of snowflake photos like stamp collectors. An American named Bentley took nearly 6,000 photos in his life.

Soviet photographer Siger Mountain is also a photographer of snowflake photos. His charming works are often used as models of structural patterns by artists. Japanese Nakatani Yoshijiro and his colleagues worked hard for 20 years, shooting and studying thousands of snowflakes in the cold room of the laboratory of Hokkaido University in Japan and in the tent on the snowfield in northern Japan.

However, although snowflakes have various shapes, they remain unchanged, so scientists may classify them into the above seven shapes. Among these seven shapes, hexagonal snowflake and hexagonal prism snowflake are the most basic forms of snowflake, and the other five are only the development, transformation or combination of these two basic forms.

[Edit this paragraph] The role of snow on human health "Medical Care News" In winter, there is heavy snow, which is endless. People often ignore the role of snow when watching Yushu Qionghua.

Snow has many benefits to human health. Compendium of Materia Medica has long recorded that snow water can detoxify and cure the plague.

There is a folk prescription for treating fire burns and frostbite with snow water. Taking a bath with snow water often can not only enhance the resistance between skin and body, reduce diseases, but also promote blood circulation and enhance physical fitness.

Drinking clean snow water for a long time can prolong life. This is one of the "secrets" of the old people who have lived in the deep mountains and forests for a long time.

Why does snow have such strange functions? Because snow water contains less heavy water than ordinary water 1/4. Heavy water will seriously inhibit the life process of living things.

After testing, fish will die quickly in water containing 30-50% heavy water. The most basic condition for the formation of rain and snow is the existence of "condensation nuclei" in the atmosphere, and solid impurities such as dust, coal particles and minerals in the atmosphere are the most ideal condensation nuclei.

If meteorological factors such as water vapor and temperature in the air reach certain conditions, water vapor will condense into snowflakes around these condensation nuclei. Therefore, snowflakes can clean a lot of pollutants in the air.

So every time after the heavy snow, the air is particularly fresh. According to measurement, the density of new snow is generally 0 per cubic centimeter.

05-0。 10g.

So, slowly.

3. Seek a scientific fairy tale about ice and snow, quickly.

Strange snow and ice

Under the sunshine, the snow and ice reflect colorful light, dazzling and beautiful. A little penguin came to a place thousands of miles away from his companion and wanted to appreciate the infinite beauty of this holy land. Looking into the distance, the south level is like a beautiful picture scroll stretching thousands of miles, and the little penguin has long been intoxicated by the picturesque scenery.

Suddenly, a loud noise pulled the little penguin out of that beautiful artistic conception. It followed the sound, and it turned out that the ice and snow were arguing endlessly and fighting for their own careers.

"At ordinary times, in the clouds in the sky, there are many ice crystals besides water droplets. When the updraft can't hold those clouds, those water droplets and ice crystals will fall to the ground. Only in spring, summer and autumn, when the temperature on the ground and near the ground is relatively high, will ice crystals melt into water in mid-air. In winter, when the ground temperature is below 0 degrees Celsius, a large number of ice crystals in the clouds fall to the ground and will not melt. They fall directly and become new snow. " Si Nuo said first.

"Water in nature has three states: gas, solid and liquid. We call liquid water, gaseous water vapor and solid water ice. The heat of fusion of ice is 3.35 *10.5 j/kg. Water is a special kind of liquid. The density is the highest at 4℃. When the temperature is higher than 4℃, liquid water obeys the general law of thermal expansion and cold contraction. Below 4℃, ice-like associated molecules appear in condensed molecules linearly distributed in water, which are called "pseudo-ice crystals". Because the density of ice is smaller than that of water, the existence of "false ice crystals" reduces the density of water, which is why the density of water is the highest at 4℃, and the density will decrease below 4℃. So far, eight kinds of ice crystals have been made in the laboratory. But only natural ice can exist under natural conditions, and others are high-pressure ice, which is not easy to exist in nature. " Ice did not show weakness, and immediately told all his understanding of the causes of ice.

"Oh, stop it," cried the little penguin. "The association of water molecules in natural ice is arranged according to the rules of hexagonal system. The simplest example of the so-called lattice is the close-packed bricks. If you replace an imaginary atom in the center of these bricks, you get a lattice. The crystal lattice of ice is a pyramid prism, and the oxygen atoms at the six corners belong to the adjacent six units. The oxygen atoms on three sides belong to three adjacent cells, and the oxygen atoms on the top of two axes belong to two cells. Only one oxygen atom in the center is unique to this cell. Snow, when the ground temperature is below 0 degrees Celsius, a large number of ice crystals in the cloud fall to the ground and will not melt. They fell straight down and turned into snow. " The little penguin's words made the ice and snow stunned. This stalemate lasted for 30 seconds, and their mood changed greatly. They are no longer stubborn.

"Oh, so that's it! If both snow and ice realized something, they said in unison. They didn't have the fierce stare just now, and smiled at each other in a friendly way. The little penguin looked at them now as good as ever, and also showed a relaxed smile.

4. What is the scientific principle of snow?

Snowflakes falling on the ground are piles of snow crystals; A single snow crystal is also called ice crystal ().

Ice crystals are ice crystals formed by water vapor molecules adhering to tiny sand grains (ice cores) in the sky and continuously condensing. The basic and common structure of ice crystals is a symmetrical hexagonal cylinder, and its actual shape is determined by atmospheric temperature, while its structure depends on humidity (supersaturation of water vapor).

When the temperature is low, the thickness of ice crystals is flat or cylindrical; However, the higher the humidity is, the structure of ice crystals changes from hexagonal columnar to needle-like or star-like dendritic. Because the temperature and humidity at high altitude will constantly change during the falling of ice crystals, every time the environment changes, ice crystals will grow new crystals on the existing structure, sometimes hexagonal columns and sometimes needles.

As a result, its shape keeps growing and changing, resulting in complex and peculiar shapes, and no two ice crystals will be exactly the same in shape, which makes people marvel at the design and creativity of nature.

5. Talk about the scientific principle of artificial snowfall.

There are two conditions for water vapor in the sky to turn into rain and snow. First, it must have a certain degree of water vapor saturation (mainly related to temperature), and second, it must have condensation nuclei. Therefore, artificial snowfall must first have clouds in the sky. There is no cloud, just like a clever woman can't cook without rice, and it won't snow. But they are all very small and light. If there are no conditions to continue to grow, they can only be suspended in the air like smoke, and it is difficult to fall.

What substance can be sprayed to promote the rapid growth of snow crystals? In the early days, people showed their magical powers and used many interesting methods. These methods mainly include: burning on the ground and releasing a lot of smoke into the sky; Attack the clouds with artillery; Fly high in the clouds with a kite, then electrify the kite and flash flowers; Fly into the clouds and spray liquid water droplets and dust particles. It was not until 1946 that people discovered that millions of snow crystals could be formed by throwing tiny dry ice particles into the Leng Yun. When artificial rainfall reaches a certain low temperature, it is snowfall.

6. Do you know the coldness of snow?

1. Snowflakes are all hexagonal? Snowflake is a beautiful crystal, also known as Weiyanghua and Liuchu. It is a snow crystal polymer formed by contacting, bonding and hooking snow crystals together.

At present, there are about 20,000 known snowflake shapes, which can be said to be colorful. The original "embryo" of snowflakes-snow crystals are basically hexagonal in shape, such as hexagonal branches and hexagonal sheets, and the snowflakes grown from them also show hexagonal characteristics.

Therefore, the ancients said that "there are five flowers in the vegetation and six snowflakes alone". The basic shape of snowflake is hexagonal, but it can show various shapes in different environments.

There are hardly two identical snowflakes in nature, just as there are no two identical people on earth. This is mainly because the temperature and humidity in the snow cloud change rapidly during the growth of snowflakes, and the shape of snowflakes will be different as long as there is a slight difference.

2. Will it snow on a sunny day? There is such a lyric in a recently popular song "Nanshan South": "You are in the sunny south, it is snowing heavily", which seems illogical at first glance. However, this phenomenon did happen, and more than once.

This phenomenon is called "solar snow". It snows when the sun is shining, so it is called "solar snow".

This phenomenon is common in the north of China and rare in the south, but it is a normal weather phenomenon. Usually, "solar snow" is a kind of short-term snowfall, which usually occurs around 9- 10 in the morning or around 15- 16 in the afternoon.

During these periods, when the clouds that produce snowfall are not thick and the coverage is not large, there may be sunlight coming out obliquely from the cracks in the clouds, so you will see the scene that sunlight and snow appear on the ground at the same time. "Solar snow" is somewhat similar to "solar rain" in summer, except that the temperature of the clouds that produce "solar snow" is low, and the precipitation falls in the form of snow.

3. "Snow particles" are not snow? Maybe everyone has seen this phenomenon: sometimes white "balls" will fall from the sky and fall to the ground. Many places call it "snow grains" or "rice snow".

In meteorology, this kind of thing is called graupel, also known as snowball or soft hail. Its diameter is generally between 0.3 and 2.5 mm, and it is brittle and fragile. But you should know that although graupel and snow are both solid precipitation, they do not belong to the category of snow.

The graupel usually lands when the ground temperature is not too cold, and usually lands before it snows, which can be said to be a "prelude" to snow. It is produced in a cloud with strong disturbance, and it is formed by a large number of snow crystals (or snow masses) colliding with Leng Yun drops and freezing, often in an array.

4. How big is the snow? We often use "lightness" and "goose feather" to describe snowflakes, which shows their lightness. Snowflakes can only be weighed on an extremely accurate analytical balance. About 3000~ 10000 snowflakes add up to one gram.

However, it can collapse houses and gas stations! Mainly because when they are together, they can gather sand into a tower and win by quantity. According to statistics, the number of snowflakes in a cubic meter of new snow can reach 8 billion! To make it easier to understand, let's first estimate the weight of snow from the perspective of precipitation.

Under normal circumstances, in the northern area of 1 m2, the snowfall thickness of 8 8~ 10/0mm melts into water, which is equivalent to the precipitation of 1 mm; In the south, the snowfall with a thickness of 6~8 mm on the area of 1 m2 melts into water, which is equivalent to the precipitation of 1 mm. According to the density of water, we can easily draw a conclusion that in the north, the snow with a thickness of 8 ~ 10 mm is about 1 kg, so it is 8 ~/kloc-0. In the south, the snow weight of 6~8 mm in the area of 100 square meter is 100 kg.

It can be seen that the snow with the same thickness is heavier in the south than in the north. More specifically, a flat roof of 100 square meters, if the snow reaches the knee, will bear the weight of 3-5 tons or more, which is equivalent to more than 20 fat people standing on the roof with a weight of about 200 kilograms. Its weight can be imagined! 5. Can snowflakes be as big as seats? "Yanshan snowflakes are as big as seats, and pieces fall on Xuanyuantai."

This is a poem by Li Bai, a great poet in the Tang Dynasty. Can snowflakes really be as big as seats? In fact, don't say that there is no record in the history of snowflake science, and even "goose feather snow" is not easy to encounter.

According to the official website of Guinness World Records, the largest snowflake reported so far was found in Fort Keogh, Montana, USA on128/00. He measured that the snowflake was 38 cm wide and 4 mm thick, "bigger than a milk pot". "* * *" said that "there is no conclusive evidence to support this statement", and now Guinness official website can't find this record.

In fact, the diameter of a single snowflake we can see is generally between 0.5 and 3.0 mm, and the maximum diameter will not exceed 10 mm, at most it is as big as our nails. Those seemingly large snowflakes, such as the so-called "goose feather snow", are actually not a snowflake, but are formed by many snowflakes sticking together.

When the air is humid, the merging ability of snowflakes is particularly great, and many snowflakes merge into one piece. Therefore, strictly speaking, goose feather snow can't be called snowflake, it is just the aggregation of many snowflakes.

6. Does the snowflake have a "core"? To form snowflakes, there are two conditions: one is that water vapor is saturated, and the other is that there must be condensation nuclei in the air. Some people have done experiments, if there is no condensation nucleus, the water vapor in the air will be supersaturated to the degree of relative humidity above 500%, and it will condense into water droplets.

But such a large supersaturation phenomenon will not exist in the natural atmosphere. So without condensation nuclei, it is difficult for us to see rain and snow on the earth.

Nucleation is a particle that plays a role in the process of changing a substance from gas to liquid or solid, or from liquid to solid. In the process of forming precipitation, the ideal condensation nuclei are those particles that absorb the most water, such as sea salt, sulfuric acid, nitrogen and other chemicals.

So the snowflake we see is actually a "core". 7. Who was the first person to take pictures of snowflakes? Wilson Bentley is an ordinary man, 1865 was born on a farm in Vermont, USA.

He has been interested in observing nature since he was a child, especially fascinated by snowflakes. He is under 19 years old.