Little scientific knowledge about snow

1. Knowledge about snow

Precipitation in the atmosphere that falls on the earth’s surface in solid form is called atmospheric solid precipitation.

Snow is the most widespread, common and dominant form of solid precipitation in the atmosphere. Atmospheric solid precipitation is diverse. In addition to beautiful snowflakes, it also includes hail that can cause great damage, as well as snow graupel and ice particles that we do not often see.

The formation of snowflakes How does water vapor moving in the sky form snowfall? Is it ok if the temperature is below zero? No, in order for water vapor to crystallize and form snowfall, two conditions must be met: One condition is that water vapor is saturated. The maximum amount of water vapor that air can contain at a certain temperature is called the saturated water vapor amount.

The temperature when the air reaches saturation is called the dew point. When saturated air cools to a temperature below the dew point, excess water vapor in the air turns into water droplets or ice crystals.

Because the saturated water vapor content of the ice surface is lower than that of the water surface, the water vapor saturation required for the growth of ice crystals is lower than that of water droplets. In other words, water droplets must grow when the relative humidity (relative humidity refers to the ratio of the actual water vapor pressure in the air to the saturated water vapor pressure of the air at the same temperature) is not less than 100%; as for ice crystals, the relative humidity is often less than 100% It can also grow over time.

For example, when the air temperature is -20°C and the relative humidity is only 80%, ice crystals can grow. The colder the temperature, the less humidity required for ice crystals to grow.

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

Someone has done experiments. If there are no condensation nuclei, the water vapor in the air can condense into water droplets only when it is supersaturated to a relative humidity of more than 500%. But such a large supersaturation phenomenon does not exist in the natural atmosphere.

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

The ideal condensation nuclei are those particles of matter that absorb the most water. For example, particles of sea salt, sulfuric acid, nitrogen and other chemicals.

So we sometimes see clouds in the sky but no snowfall. In this case, people often use artificial snowfall. Snowflakes that do not condense in the sky Snow falls from the sky, so how can there be snowflakes that do not condense in the sky? In the winter of 1773, a newspaper in Petersburg, Russia, reported a very interesting news.

This news said that 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 ladies who were in poor health almost died. To faint before the god of joy. At this time, a young man jumped on the window sill and broke the glass with a punch.

Then, an unexpected miracle appeared in the ballroom. Beautiful snowflakes danced in the hall with the cold air outside the window, falling on the hair and hands of people who were dizzy from the heat. Some people rushed out of the ballroom curiously to see if it was snowing outside.

What is amazing is that the sky is bright with stars and the new moon is as silver as water. So, where did the snowflakes in the hall come from? This is really a puzzling question.

Could someone be playing some magic trick? But no matter how good the magician is, he can't make snowflakes appear in the hall. Later, scientists solved this mystery.

It turned out that the breath of many people in the dance hall was full of water vapor, and the burning of candles spread many condensation nuclei. When the cold air outside the window breaks in, it forces the saturated water vapor in the hall to immediately condense and crystallize, turning into snowflakes.

Therefore, as long as the conditions for snow are met, it will snow in the house. The Basic Shapes of Snowflakes Snowflakes are beautiful to look at, but scientists and arts and craftsmen marvel at the small, delicate patterns of snowflakes.

More than a hundred years ago, glaciologists had begun to describe the shape of snowflakes in detail. Tyndall, the originator of Western glaciology, described the snowflakes he saw on Roza Peak in his classic glaciology work: "These snowflakes... are all composed of small ice flakes, and each small ice flower has six pieces. The petals, some have beautiful little lateral tongues like shansu flowers, some are round, some are arrow-shaped, or zigzag-shaped, some are complete, and some are grid-shaped, but none exceed six "The scope of the petal type."

In our country, as early as more than 100 years ago in the era of Emperor Wen of the Western Han Dynasty, there was a poet named Han Ying. He wrote a book called "Han Shi Wai Zhuan". The book clearly points out that "every plant has five flowers, but snowflakes only have six." The basic shape of snowflakes is hexagonal, but there are almost no two identical snowflakes in nature, just like there are no snowflakes on the earth. Two identical people.

Many scholars have used microscopes to observe thousands of snowflakes. These studies have finally shown that snowflakes with exactly the same shape and size and complete symmetry of each part cannot be formed in nature. Among the snowflakes that have been observed by people, no matter how regular and well-proportioned they are, there are also deformities.

Why are snowflakes deformed? Because the water vapor content in the atmosphere around the snowflake cannot be the same in all directions, up and down, as long as there is a slight difference, the side with more water vapor content will always grow faster. There are many collectors of snowflake patterns in the world, and they collect all kinds of snowflake photos like stamp collectors.

There is an American named Bentley who spent his life taking nearly 6,000 photos. Soviet photography enthusiast Sigshan was also a photographer of snowflake photos. His ecstatic works are often used by industrial artists as models for structural patterns.

Japanese Ukichiro Nakatani and his colleagues worked hard for twenty years in a cold room in the laboratory of Hokkaido University in Japan and in a tent on the snowy fields in northern Japan, photographing and studying thousands of snowflakes. However, although the shapes of snowflakes come in all shapes and sizes, they remain the same, which is why scientists can summarize them into the seven shapes mentioned above.

Among these seven shapes, hexagonal snow flakes and hexagonal prism-shaped snow crystals are the most basic forms of snowflakes, and the other five are just the development, metamorphosis or combination of these two basic forms. The Effect of Snow on Human Health "Medicine and Health Care News" In winter, heavy snow falls and the sky is boundless.

When people watch Yushu and Qionghua, they often ignore the role of snow. Snow has many benefits for human health.

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

2. I am in urgent need of scientific knowledge about snow~ Experts can help me, I am offering a high reward

Overview of Snow Water is the foundation for the existence of all living things on the earth. The changes and movements of water create of our world today.

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

Precipitation in the atmosphere that falls on the earth's surface in a solid form is called atmospheric solid precipitation. Snow is the most dominant form of solid precipitation in the atmosphere.

In winter, precipitation in many areas of our country appears in the form of snow. The size, shape, and density of the snowflakes that fall to the ground vary.

Therefore, the meteorological snow level is measured by the water after the snow melts. Meteorologically, snow is generally divided into four levels based on the amount of precipitation within 24 hours: 0.1-2.4 mm of snow is called light snow; 2.5-4.9 mm of snow is called moderate snow; 5.0-9.9 mm of snow is called heavy snow; 10 mm of snow is called heavy snow. Snow above (including 10 mm) is called blizzard.

In terms of precipitation, even heavy snowfall is only equivalent to moderate rain. A rough estimate is that 10 mm of snow can melt into only 1 mm of water.

Supplement: Atmospheric solid precipitation is diverse. In addition to snowflakes, it also includes hail that can cause great harm, as well as snow graupel and ice particles that we do not often see. Due to differences in meteorological conditions and growth environments in the sky, various atmospheric solid precipitations are caused.

The names of these atmospheric solid precipitations vary from place to place and from person to person. The names are numerous and extremely inconsistent. For the sake of convenience, the International Snow and Ice Committee of the International Hydrological Association convened a specialized international conference in 1949 on the basis of soliciting opinions from experts from various countries. At the meeting, a proposal for a concise classification of atmospheric solid precipitation was adopted.

This concise classification divides atmospheric solid precipitation into ten types: snow flakes, star-shaped snowflakes, columnar snow crystals, needle-shaped snow crystals, dendritic snow crystals, axis-shaped snow crystals, and irregular snow crystals , graupel, ice particles and hail. The first seven are collectively called snow.

Why can’t the latter three be called snow? It turns out that there are two processes for turning gaseous water vapor into solid water. One is that the water vapor first turns into water, and then the water condenses into ice crystals; the other is that the water vapor directly turns into ice crystals without passing through water. This process is called water vapor. Sublime. Therefore, snow is solid precipitation formed by the condensation of water vapor in the sky.

The Basic Shapes of Snowflakes Snowflakes are beautiful to watch, but scientists and arts and craftsmen are most impressed by the small, delicate patterns of snowflakes. More than a hundred years ago, glaciologists began to describe the shape of snowflakes in detail.

Tyndall, the originator of Western glaciology, described the snowflakes he saw on Roza Peak in his classic glaciology work: "These snowflakes... are all composed of small ice flakes, each one Each small ice flower has six petals. Some petals release beautiful little tongues like shansu flowers. Some are round, some are arrow-shaped, or zigzag-shaped, some are complete, and some are in a grid. shape, but they do not exceed the scope of the six-petal type." In our country, as early as more than 100 years ago in the era of Emperor Wen of the Western Han Dynasty, a poet named Han Ying wrote a book called "Han Shi Wai Zhuan". The book clearly points out that "every plant has five flowers, but snowflakes only have six."

The basic shape of snowflakes is hexagonal, but it is almost impossible to find two identical snowflakes in nature. Just like there are no two identical people on earth.

Many scholars have observed thousands of snowflakes with microscopes. These studies have finally shown that snowflakes with exactly the same shape and size and complete symmetry of each part cannot be formed in nature.

Among the snowflakes that have been observed by people, no matter how regular and symmetrical the snowflakes are, there are also deformities. Why are snowflakes deformed? Because the water vapor content in the atmosphere around the snowflake cannot be the same in all directions, up and down, as long as there is a slight difference, the side with more water vapor content will always grow faster.

There are many collectors of snowflake patterns in the world. They collect all kinds of snowflake photos like stamp collectors. There was an American named Bentley who spent his life taking nearly 6,000 photos.

Soviet photography enthusiast Sigshan was also a photographer of snowflake photos. His ecstatic works are often used by arts and crafts artists as models for structural patterns. The Japanese Ukichiro Nakatani and his colleagues worked hard for twenty years in a cold room in the laboratory of Hokkaido University in Japan and in a tent on the snowfields of northern Japan, photographing and studying thousands of snowflakes.

However, although the shapes of snowflakes come in all shapes and sizes, they remain the same, so it is possible for scientists to classify them into the seven shapes mentioned above. Among these seven shapes, hexagonal snow flakes and hexagonal prismatic snow crystals are the most basic forms of snowflakes, and the other five are just the development, metamorphosis or combination of these two basic forms.

[Edit this paragraph] The effect of snow on human health "Medicine and Health Care News" In winter, there is heavy snow and endless sky. When people appreciate Yushu and Qionghua, they often ignore the role of snow.

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

Folks use snow water to treat fire burns and frostbite. Regular bathing with snow water can not only enhance the resistance of the skin and body and reduce diseases, but also promote blood circulation and enhance physical fitness.

If you drink clean snow water for a long time, you can live longer. This is one of the "secrets" for those long-lived old people living in the deep mountains and forests to live long.

Why does snow have such strange functions? Because the amount of heavy water contained in snow water is 1/4 less than that in ordinary water. Heavy water can seriously inhibit biological life processes.

Someone has done experiments and found that 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 ideal condensation nuclei.

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

Therefore, the air seems particularly fresh after a heavy snowfall. According to measurements, the density of new snow is generally 0 per cubic centimeter.

05-0. 10 grams.

So, land.

3. Looking for a scientific fairy tale about ice and snow, please hurry up

Strange ice and snow

Under the sunlight, a streak of light is reflected on the ice and snow The colorful light is dazzling and beautiful. A little penguin came to a place thousands of miles away from its companions, wanting to appreciate the infinite beauty that exists in this holy land. Looking from a distance, the south level is like a beautiful scroll of thousands of miles, and the little penguin has already been intoxicated by the picturesque scenery.

Suddenly, a burst of noise pulled the little penguin out of the beautiful artistic conception. It followed the sound, and it turned out that ice and snow were arguing endlessly, and they were fighting over the reasons for their formation.

"Usually, in the clouds in the sky, besides water droplets, there are also many ice crystals. When the updraft cannot support those clouds, those water droplets and ice crystals will fall towards the ground. But it's just that In the spring, summer, and autumn seasons, the temperature on the ground and close to the ground is relatively high, so the 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 disappear. When the ground falls, it won't be melted, it will fall directly and turn into snow," Xue said first.

"Water in nature has three states: gaseous, solid and liquid. The liquid is called water, the gaseous water is called water vapor, and the solid water is called ice. The heat of fusion of ice is 3.35*10 ^5J/kg. Water is a special liquid. Its density is maximum at 4℃. When the temperature is above 4℃, liquid water follows the general law of thermal expansion and contraction, and the condensed molecules in the water are originally linearly distributed. In , there is an ice-like association molecule with the same structure as ice crystal, called "pseudo-ice crystal". Because the density of ice is smaller than that of water, the existence of "pseudo-ice crystal" reduces the density of water, which is why water is there. The secret is that the density is maximum at 4°C and decreases below 4°C. So far, eight types of ice crystals have been produced in the laboratory, but only natural ice can exist under natural conditions. High-pressure ice is not easy to exist in nature. "Bing didn't show any signs of weakness. He immediately told everything he knew about the formation of ice.

"Hey, stop arguing." The little penguin said loudly, "The association of water molecules in natural ice is arranged according to the rules of the hexagonal crystal system.

The simplest example of a so-called crystalline lattice is bricks that are tightly packed. If a hypothetical atom is replaced at the center of these bricks, a crystalline lattice is obtained. The crystal lattice of ice is a triangular prism with a top cone, and the oxygen atoms at the six corners are owned by the six adjacent unit cells. The oxygen atoms on the three edges are each owned by three adjacent unit cells. The two apex oxygen atoms are each owned by two unit cells. Only the central oxygen atom is unique to the unit cell. . As for snow, 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 be melted. They fall directly and become snow. "The words of the little penguin made Bing and Xue suddenly stunned. This deadlock lasted for thirty seconds. Their emotions had changed greatly, and they were no longer unwilling to give in to each other.

"Oh, so that's it! ''Bing and Xue both realized something and said in unison. They no longer had the fierce expressions and angry eyes before, and smiled friendly at each other. The little penguin looked at the way they were now reconciled, and also showed relief. smile.

4. What is the scientific principle of snow

Snow flakes falling on the ground are made up of a pile of snow crystals; a single snow Crystals are also called ice crystals ().

Ice crystals are formed by water vapor molecules in high altitude attached to extremely small grains of sand (ice nuclei), which are continuously condensed into ice crystals. The basic, common structure of ice crystals is a symmetrical hexagonal prism, whose actual shape is determined by atmospheric temperature, while the structure depends on humidity (the degree of supersaturation of water vapor).

When the temperature is lower, the thickness of the ice crystals takes on the shape of flat plates or cylinders; when the humidity is higher, the ice crystal structure changes from hexagonal columns to needles or star-shaped dendrites. As the ice crystals fall, the temperature and humidity at high altitude they face will continue to change. Every time the environment changes, the ice crystals will grow new crystals outward on the existing structure, sometimes in the shape of hexagonal columns, sometimes in the shape of needles.

As a result, its shape continues to grow and change, deriving into complex and peculiar forms, and the shapes of any two ice crystals are not exactly the same, which makes people marvel at the design and creativity of nature.

5. Talk about the scientific principles of artificial snowfall

For water vapor in the sky to turn into rain and snow, it must meet two conditions. One is that it must have a certain degree of water vapor saturation (mainly related to temperature), the other is that there must be condensation nuclei. Therefore, artificial snowfall must first have clouds in the sky. Without clouds, it is like a skillful woman cannot make a meal without rice, and it cannot snow. But they are very small and light. If there are no conditions for continued growth, they can only be suspended in the air like smoke and dust, and it is difficult to fall down.

What substances can be sprayed to make snow crystals grow quickly? In the early days, people used many interesting methods to show their talents. These methods mainly include: setting fires on the ground and releasing a large amount of smoke into the sky; using cannons to attack clouds; using kites to fly high into the clouds, and then electrifying the kites to discharge sparks; flying into clouds by airplane to spray liquid water droplets and dust particles . It wasn't until 1946 that people discovered that putting tiny particles of dry ice into cold clouds could form millions of snow crystals. Snow falls when artificial rainfall reaches a certain low temperature.

6. Do you know the "cold" knowledge about snow?

1. Are all snowflakes hexagonal? Snowflake is a kind of beautiful crystal, also known as Weiyang flower and Liuchu. It is a snow crystal polymer formed by the collision, adhesion and hooking of snow crystals with each other.

There are currently more than 20,000 known shapes of snowflakes, which can be said to be of all shapes and colors. However, the shape of snow crystals, the original "embryo" of snowflakes, is basically hexagonal, such as hexagonal branches, hexagonal flakes, etc., and the snowflakes grown from them also mostly show hexagonal characteristics.

Therefore, the ancients said that "there are five flowers in vegetation, but six in snowflakes alone." The basic shape of snowflakes is hexagonal, but they can take on a variety of shapes under different circumstances.

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

2. Can there be “heavy snowfall” in the bright sun? There is a line in the recently popular song "Nan Shan Nan": "You are in the bright sunshine in the south, with heavy snow falling." It may sound illogical at first. 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 relatively common in northern my country and rare in the south, but it is a normal weather phenomenon. Usually "solar snow" is a short-term snowfall, which usually occurs around 9-10 am in the morning or around 15-16 pm in the afternoon.

During these periods, when the clouds that produce snowfall are not thick and cover a small area, there may be sunlight slanting out from the gaps in the clouds, so you will see sunlight and snow on the ground at the same time. scene. "Solar snow" is somewhat similar to the "solar rain" that occurs in summer, except that the temperature of the clouds that produce "solar snow" is lower, and the precipitation falls in the form of snow.

3. "Snow particles" are not snow? Maybe everyone has seen this phenomenon: sometimes white "little balls" fall from the sky and jump on the ground. In many places, it is called "Xue Li" or "Mi Xue" colloquially.

In meteorology, this kind of thing is called graupel, also known as snow pellet or soft hail. Its diameter is generally between 0.3 and 2.5 mm. It is brittle and can be easily crushed. But did you know that although graupel and snow are both solid precipitation, they do not fall into the category of snow.

Graupel usually falls when the ground temperature is not too cold. It usually falls before snowfall, which can be said to be the "prelude" of snowfall. It is produced in highly disturbed clouds. It is formed by large amounts of snow crystals (or snow masses) colliding with supercooled cloud droplets, causing them to freeze and merge. It often appears in bursts.

4. How heavy is the snow? We often describe snowflakes as "lightly dancing and flying" and "goose feather", which shows how light they are. The weight of snowflakes can only be measured on an extremely precise analytical balance. About 3,000 to 10,000 snowflakes add up to weigh 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, there are up to 8 billion snowflakes in one cubic meter of new snow! To make it easier to understand, let’s estimate the weight of snow from the perspective of precipitation.

Under normal circumstances, the snowfall thickness of 8~10 mm on 1 square meter in the north melts into water equivalent to 1 mm of precipitation; while in the south, the snowfall thickness on 1 square meter is 6~8 mm Melting into water is equivalent to 1 mm of precipitation. According to the density of water, it is not difficult to conclude that in the north, 8-10 mm of snow on an area of ??1 square meter weighs about 1 kilogram. Then, 8-10 mm of snow on an area of ??100 square meters weighs 100 kilograms; In the south, 6 to 8 mm of snow on 100 square meters weighs 100 kilograms.

It can be seen that for the same thickness of snow, the snow with higher moisture content in the south is heavier than the snow in the north. To be more specific, if the snow on a 100-square-meter flat roof is knee-deep in snow, it will bear a weight of more than 3-5 tons. This is equivalent to more than 20 fat people weighing about 200 kilograms standing on the roof. The weight can be imagined! 5. Is it possible for snowflakes to be “as big as a mat”? "The snowflakes on Yanshan Mountain are as big as mats, and they fall down on Xuanyuan Terrace."

This is a poem by Li Bai, a great poet of the Tang Dynasty. Can snowflakes really be as big as a mat? In fact, let alone the fact that there is no record of snowflakes as big as a mat in the history of science, even snowflakes as big as goose feathers are not easy to encounter.

According to the Guinness World Records official website, the largest reported snowflake was discovered by farmer Matt Coleman in Fort Keogh, Montana, USA on January 28, 1887. He measured the snowflake. It is 38 centimeters wide and 4 millimeters thick, "bigger than a milk pot." "***" stated that "there is no conclusive evidence to support this statement", and now this record can no longer be found on the Guinness official website.

In fact, the diameter of the individual snowflakes we can see is generally between 0.5 and 3.0 mm, and the maximum diameter does not exceed 10 mm, at most the size of our fingernails. Those snowflakes that look relatively large, such as the so-called "goose feather snow", are actually not one snowflake, but are formed by many snowflakes stuck together.

When the air is relatively humid, the ability of snowflakes to merge is particularly strong, and many snowflakes often merge into one. Therefore, strictly speaking, goose feather snow cannot be called snowflakes, it is just an aggregate of many snowflakes.

6. Do all snowflakes have "cores"? In order to form snowflakes, two conditions must be met: one condition is that water vapor is saturated, and the other condition is that there must be condensation nuclei in the air. Someone has done experiments and found that if there are no condensation nuclei, the water vapor in the air can condense into water droplets only when the relative humidity is over 500%.

But such a large supersaturation phenomenon does not exist in the natural atmosphere. Therefore, without condensation nuclei, it would be difficult to see rain and snow on our earth.

Condensation nuclei are particles that play the role of condensation cores during the condensation process when matter is converted from gaseous state to liquid or solid state, or from liquid state to solid state. In the process of forming precipitation, the ideal condensation nuclei are those particles of substances that absorb water the most, such as particles of sea salt, sulfuric acid, nitrogen and other chemical substances.

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

He has been interested in observing the natural world since he was a child, and was especially fascinated by snowflakes. He was less than 19 years old.