Snow is an air-water formation that falls in the form of precipitation as a result of condensation and hardening processes in the upper layers of the atmosphere. Depending on the condensation conditions, the size, shape and structure of snowflakes may vary. In general, snow, when it falls at least a few times during the winter, provides the important function of storing moisture for plants to return to growth when spring arrives. 
With the advent of the technical ability to study the structure of snowflakes, more than 10 different forms that were similar to each other within a group of their forms were identified. These include: lamellar, stellate and volumetric formations of dendritic structure, needle-shaped, columnar and irregularly shaped. 
The white color of snow is due to the presence of air in its composition.
Since air plays a predominant role in the composition of snow, light falling on the surface of ice crystals is scattered in different directions. Light in them can propagate in all directions, regardless of the spectral wavelength. 
Large amounts of snow can lead to flooding and provoke dangerous high-speed landslides in mountainous conditions.
The airy composition of snow described above does not mean that it is harmless, especially in large quantities. For example, snow cover on the surface of a hectare can produce about 30 m 3 of water when melting, which can threaten flooding of low-lying areas of the relief. On the other hand, exposure to snow in mountainous conditions is deadly, where sometimes a few snowflakes falling on the surface with insufficient critical mass can trigger a snowfall. The danger of landslides is their high speed, which is in the range of 250-400 km/h.
Scientists spent 26 billion on studying the process of snowflake formation
Not having sufficient means and methods to study the process of formation of snow crystals, scientists spent 26 400 000$ . As a result, they found out a rather simple fact, which is that snow crystals are formed from steam that evaporates from the surface of the earth, skipping the rain phase, under conditions of condensation and low temperatures.
Under the influence of snow, the Earth may be left without solar heat
Snow, can only perceive 5-10% solar heat, the remaining 90-95% are reflected back. In the conditions of a nuclear winter, if it occurs, humanity risks losing not only heat in places where the surface is covered with snow, but also food and oxygen produced by plants.
There is a snowflake museum in Japan
The Japanese are distinguished by their reverent attitude towards snow and snowflakes, believing that on their islands they are special, different from everyone else in the world. The prerequisite for the founding of the snowflake museum on the island of Hokkaido was the publication in 1954 of a book about the types of snowflakes by Ukihiro Nahaya. 
The creaking of snow appears only in frosty weather
Indeed, the creaking of snow, which is a crunching sound, is formed when many small needles of crystals are exposed and occurs exclusively in the temperature range below -3°C. At a temperature below the specified temperature by 3 degrees, the noise produced has a high-frequency characteristic.
The diameter of the crystals is extremely small
Most snowflakes in diameter fluctuate within a certain range around 5mm, but in 1987, crystals with a diameter of 38mm were recorded in the American state of Montana. 
History has recorded snow falling in various shades, from black to pink.
On Christmas Eve 1963, black snow fell on one piece of land. Scientists associated this fact with the high pollution of the atmosphere in this area, as a result of which the snow absorbed soot when passing to the ground.
Snow is edible
It is possible to eat snow, but its use requires several times more than other products. It should also be noted that the amount of energy spent on its consumption is many times greater than the calorie content of the product.
- There is a Snow Festival. Indeed, such a day exists because, in addition to its aesthetic function, snow often plays an important role in agriculture. International Snow Day is celebrated January 19.
- A huge amount of snow falls during the winter. Every year, according to average indicators, about septillion snowflakes fall on Earth in the form of precipitation. A septillion is a number containing 24 zeros after one.
- The weight of a snowflake is very small. The average weight of an ordinary snowflake is 1 mg, but for larger samples of irregular shape, which have taken on ice particles as they move towards the ground, it can be 2-3 mg.
- The main component of snowflakes is air, which causes their low speed. Typically, they consist of 90-95% air, and since air has a low density, this causes their low speed of movement towards the ground. On average it is about 0.9-1 km/h.
- A cubic meter of snow contains millions of snowflakes. A volume of 1 m 3 of snow can contain up to three and a half hundred million snowflakes, each of which has a unique structure.
- There are people who have never seen snow in their lives. In fact, the number of such people is large and constitutes approximately half of the world's population.
- There are methods for artificially producing snow. After studying the mechanism of snowflake formation, the idea of creating snow in laboratory conditions became possible and came to life.
- Snow also exists on other planets and satellites. Research has confirmed that on Mars snow falls in the form of carbon dioxide, while on Titan it consists of methane.
During an ordinary snowfall, we do not think that an ordinary snowflake, when studied through a microscope, can present a beautiful sight and amaze us with the correctness and complexity of its forms. snowfall consists of such beauty.
By the way, the snow itself is not only white. In arctic and mountainous regions, pink or even red snow is common. The fact is that algae living between its crystals color entire areas of snow. But there are cases when snow fell from the sky already colored - blue, green, gray and black.
So, on Christmas Day 1969, black snow fell in Sweden. Most likely, this happened due to the fact that the snow, when falling, absorbed soot and industrial pollution from the atmosphere. In any case, laboratory testing of air samples revealed the presence of the insecticide DDT in the black snow
The mathematician was especially struck by the “tiny white dot” he found in the middle of the snowflake, as if it were the trace of the leg of a compass that was used to outline its circumference.
The great astronomer Johannes Kepler in his treatise “New Year's Gift. On Hexagonal Snowflakes” explained the shape of crystals by the will of God. Japanese scientist Nakaya Ukichiro called snow “a letter from heaven, written in secret hieroglyphs.”
He was the first to create a classification of snowflakes. The world's only snowflake museum, located on the island of Hokkaido, is named after Nakai.
Complex star-shaped snowflakes have a unique geometric shape that can be distinguished by the eye. And there are more variants of such forms, according to physicist John Nelson from Ritsumeikan University (Japanese) in Kyoto, than there are atoms in the observable Universe.
During a snowfall in 1987, a world record snowflake with a diameter of 38 cm was found in Fort Coy (Montana, USA).
Any of us knows very well that one snowflake is practically weightless: it is enough to place your palm under the falling snowball.
An ordinary snowflake weighs about a milligram (very rarely 2-3 milligrams), although there are exceptions - the largest snowflakes fell on April 30, 1944 in Moscow. Caught in the palm, they covered almost the entire palm and resembled ostrich feathers.
More than half the world's population has never seen snow, except in photographs.
A layer of one centimeter of snow compacted over the winter provides 25-35 cubic meters of water per 1 hectare
Snowflakes consist of 95% air, which causes low density and a relatively slow falling speed (0.9 km/h).
You can eat snow. True, the energy consumption of eating snow is many times greater than its calorie content.
A snowflake is one of the most fantastic examples of self-organization of matter from simple to complex.
In the Far North, the snow can be so hard that when an ax hits it, it rings as if struck by iron.
The shapes of snowflakes are incredibly diverse - there are more than five thousand variations. Even a special international classification has been developed in which snowflakes are combined into ten classes. These are stars, plates, columns, needles, hail, tree-like crystals resembling fern stems. The sizes of the winter miracle range from 0.1 to 7 millimeters.
The creaking of snow is just noise from crushed crystals. Of course, the human ear cannot perceive the sound of one “broken” snowflake. But the myriads of crushed crystals create a very clear creaking sound. Snow creaks only in cold weather, and the pitch of the creaking changes depending on the air temperature - the stronger the frost, the higher the pitch of the creaking. Scientists made acoustic measurements and found that in the spectrum of snow creaking there are two gentle and not sharply expressed maxima - in the range of 250-400 Hz and 1000-1600 Hz.
Snowflakes viewed through a microscope are God's wonderful handiwork. Each crystallized raindrop - which is snow - has a certain systematic pattern with countless varieties - several of them are represented in the figure.
When it snows, we don’t think that an ordinary snowflake under a microscope is a beautiful sight and amazes with its regularity and complexity of shape. Snowflakes look like roses, lilies and wheels with six teeth. He was especially struck by the “tiny white dot” he found in the middle of the snowflake, as if it were the trace of the leg of a compass that was used to outline its circumference.”
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Target: broadening the horizons and developing the cognitive interest of students; speech development.
1. -Guess the riddles. And we will find out the topic of our class hour.
1) I, like a grain of sand, am small and cover the earth, I was born from water and I give birth to it myself.
2) I lie like fluff in the fields and, like a diamond, shine in the sun’s rays.
3) There is one such flower, you cannot weave it into a wreath. Blow lightly on it - there was a flower - and there is no flower. (Snowflakes)
Right. Today we will talk about snowflakes.
White snowflakes fall, lie on the ground, on the roofs of houses. Passers-by are showered with hats and collars. Snowflakes look like white stars. Like lace, all different, with thin rays, with petals, like the most delicate flowers.
Where did the snowflakes form?
Snowflakes formed in clouds from small ice crystals. In winter, they descend like sparkling stars to the very ground and cover it with snow.
Run in the snow on a clear, frosty day.
Can you hear the snow creaking under your feet? Do you know why?
These are the small rays of cold stars crackling and creaking, breaking under your feet.
What else do you know?
Student information.
Each cubic meter of snow contains about 350 million snowflakes. None of them repeat each other. A snowflake weighs about a milligram, very large snowflakes weigh 2-3 mg.
Snowflakes are 95% air.
The world's largest snowflakes were recorded in 1944 on April 30 in Moscow. They covered the palm and looked like ostrich feathers.
Student 3 reads the poem “Blizzards have arrived.” (G. Ladonshchkov)
Snowstorms have arrived to us,
They covered the cracks with snow.
Old man Frost on the window
I painted it with ice.
Why do patterns appear on windows?
Frost draws them.
How does he draw them?
Transparent water vapor that is always in the air. He is also in the room. And between the double window frames - everywhere! Warm water vapor settles on the cold glass of the windows and turns into ice crystals, just like snowflakes in the sky. Ice crystals connect with each other. Ice floes cluster on uneven surfaces, on barely noticeable scratches on the glass, and an ice garden gradually grows on the window with unusual flowers sparkling in the rays of the winter sun.
Where is snow born?
Water vapor rises very high above the ground, where intense cold reigns, and here tiny ice crystals immediately form from the water vapor. These are not yet the snowflakes that fall to the ground, they are still very small. But the hexagonal crystal grows and develops all the time and finally becomes an amazingly beautiful star. Snowflakes slowly and slowly fall, they gather in flakes and fall to the ground.
There is the only museum in the world - the Museum of Snowflakes. In Japan, on the island of Hokkaido, there is a Snowflake Museum. The founder of the snowflake museum is Nakaya Ukichiro, a scientist whose name the museum bears.
The museum was created right in the caves. The halls display photographs of snowflakes in a variety of forms. The first person to photograph snowflakes was US farmer Wilson Bentley. In 1931 he published an album with these unique snowflakes (2500 pictures in total).
Correspondence excursion “To the Museum of Snowflakes”
Thanks everyone for the information. Well done!
Additional material “To help the teacher.”
1. Poems about snowflakes
Snowflakes. S. Baruzdin
Winter is full of snow
From morning until dark.
Snowflakes curl and spin
At our window.
It's like the stars are sparkling
Scattered around.
They rush, silvery,
They look into the house.
Then they will ask you to come into the room,
They'll run away again
They rush behind the glass,
They're calling me to go outside.
Snowflakes. M. Klokova
Snowflakes, snowflakes
On Ninka's cheeks,
Stuck in braids
Hanging on eyelashes
They make it difficult to watch.
She squeezed it in her palm,
I wanted a little
Warm the snowflakes.
I pressed it tighter,
But what happened to them?
What a disaster!
The snowflakes have disappeared
In Ninka's palm
Only one water!
Blank verses. Sergey Mikhalkov
The snow is spinning
The snow is falling -
Snow! Snow! Snow!
The beast and the bird are glad to see the snow
And, of course, a person!
Dance of snowflakes. Alexander Tvardovsky
We are white snowflakes
We fly, we fly, we fly.
Paths and paths
We'll screw it all up.
Let's circle over the garden
On a cold winter day
And we'll sit quietly next to you
With people like us.
We dance over the fields
We lead our own round dance,
Where, we don’t know ourselves,
The wind will carry us.
2. A snowflake is a very interesting natural phenomenon
2.1. How are snowflakes born?
Fragile, lightest snowflakes travel a long and whimsical path, sometimes contrary to the laws of physics. They originate in clouds, condensing from water vapor in the form of tiny droplets. Then the droplets cool to a temperature below 0 °C, but do not freeze.
Only specks of dust floating in the air contribute to their transformation into snow; the specks of dust become the center of crystallization. Other water molecules join the core of the crystal in strictly defined places, “constructing” snowflakes of a distinctly hexagonal shape.
As they approach the Earth, they attract more and more drops to themselves, gradually increasing in size. When snowflakes reach critical mass, they fall to the ground.
The shape of snowflakes depends on the temperature of the air around them (found out by Ukihiro Nakaya). But snow flakes, rushing to the ground, pass through many layers of air in the atmosphere with different temperatures. This constant alternation of temperature turns snow crystals into a unique creation.
2.2. The mystery of the snowflake.
The designs of snow crystals, full of perfect harmony, aroused the interest of the minds of bygone times and modern scientists. The first sketches of various forms of snowflakes were made by the Swiss explorer Mangus in 1555.
German astronomer Johannes Kepler found that almost all snowflakes are six-pointed crystals. in 1611 he published his work "De nive sexangula" (On hexagonal snowflakes).
French philosopher and mathematician René Descartes wrote in 1635 that snowflakes resemble roses, lilies and six-pronged wheels, and in 1637 he first published realistic sketches of snowflakes. In his sketches you can even see twelve- and eighteen-pointed crystals, which are very rare in nature.
Japanese physicist Nakaya Ukichiro called snow “a letter from heaven, written in secret hieroglyphs.” This scientist was the first to become interested in snowflakes from a scientific point of view in the 1930s and made a huge contribution to their study. He created a machine for artificially producing snow and the first classification of snowflakes. The world's only Museum of Snow and Ice, located on the island of Hokkaido in the city of Kaga, is named after Nakai.
In the 90s, astronomer Kenneth Libbrecht adopted a classification of solid sediments. In 1955, the Russian scientist A. Zamorsky divided all snowflakes into 9 classes and 48 types: plates, needles, stars, hedgehogs, columns, fluffs, cufflinks, prisms and others.
In the 90s, astronomer Kenneth Libbrecht, a professor at the California Institute of Technology, began his research in the field of snow. In his laboratory, snowflakes are grown artificially. At the moment, there is a whole team of people creating exclusive designer snowflakes, including custom ones.
One of those people who was inexplicably attracted by the beauty of snowflakes was an American farmer from Vermont, Wilson “Snowflake” Bentley (1865-1931). He was obsessed with the dream of photographing snowflakes. “I discovered that snowflakes were a wonderful embodiment of beauty,” Bentley wrote, “and it seemed a shame to me that this beauty would not be seen and appreciated by others. Each crystal was an example of a magnificent pattern, and not a single pattern was repeated twice. When the snowflake melted, the pattern disappeared forever. It was as if beauty was leaving forever, leaving no trace behind.” On January 15, 1885, after many trials and errors, Bentley took the first successful photograph of a snowflake under a microscope. He did this for forty-six years, taking more than 5,000 unique photographs. Based on his work, it was proven that there is not a single pair of absolutely identical snowflakes. In 1931, Bentley published the album “Snow Crystals,” containing more than 2,500 photographs of snowflakes. And after his death in 1935, the atlas “Snow Crystals” he compiled was published.
2.3. About the benefits of snowflakes.
The snow cover that covers the ground during the winter months is vital for plants. He saves them from freezing. Loose snow contains a large amount of air. Sometimes a “snow feather bed” consists of 90 percent air filling, which is known to be an excellent insulator. Snowflakes serve people well too. They clean the air of dust and fumes, and therefore it is always easy to breathe during snowfall. Moreover, snow reflects the destructive spectra of the sun's rays, so northern peoples do not have many of the diseases that southerners suffer from.
3. Riddles about snowflakes
What kind of carved stars
On a coat and on a scarf?
All through, cut-out,
And if you take it, there is water in your hand. (Snowflakes)
The star spun
There's a little in the air
Sat down and melted
On my palm. (Snowflake)
Stars are falling from the sky,
They will lie down in the fields.
Let him hide under them
Black earth.
Many, many stars
Thin as glass;
The stars are cold,
And the earth is warm! (Snowflakes)
fall from the sky in winter
And they circle above the ground
Light fluffs,
White... (Snowflakes)
Therefore, you and I are very lucky that we have the opportunity to admire both the beauty of the first spring flowers and the thick snowfalls outside the window.
Today I will tell you some interesting things about snowflakes. I'm sure you will be something to surprise your friends!
Do you know that a snowflake is 95% air? This is why snowflakes fall to the ground so slowly, as if spinning in a slow dance. Scientists even measured the speed of their fall - 0.9 km/h.
The fact that a snowflake has air in its structure explains it White color. Light is reflected from ice crystals and air and scattered, which is why we see this winter beauty as silvery white.
But history knows cases when snow fell in other colors. Black snowfall shocked the residents Sweden in 1969, and California in 1955 I saw green snow. Wow!
Who colors the snow in such unusual colors for us? Scientists say that interesting creatures live in the snow of the Antarctic mountains - snow chlamydomonas. So they make the snow pink, red, purple and even yellow.
Another interesting fact: when falling into water the snowflake "sings", creating a very high-pitched sound, inaudible to the human ear. But fish He hears him perfectly well, and, moreover, he really doesn’t like him.
Have you ever wondered why it is so cold in winter? This snow reflects 90% of light from the earth's surface without letting it warm up.
The world's largest snowflake found in USA in 1987. The diameter of the giant beauty was as much as 38 cm!
And in Moscow On April 30, 1944, the strangest snow in human history fell. Snowflakes the size of your palm were circling over the city, and in shape they resembled... ostrich feathers.
Snow is incredible numbers that amaze our imagination. In order for one snowflake to crystallize from water vapor, a million water drops are needed. And in just one winter, on average, one septillion snowflakes fall on the ground. A septillion is one trillion trillion, a number with 24 zeros after the one. Now try to find out the number of water droplets by multiplying septillion by a million...
The snow flies and spins because snowflakes are almost weightless. And it’s not surprising: after all, they consist of only 5% water. Therefore, in calm, windless weather, the falling speed of a snowflake weighing 1 milligram does not exceed 0.9 km/h. But given the mind-boggling numbers of snowflakes, this is apparent ease. Suffice it to say that just 1 cm of snow cover on a hectare of area can provide from 25 to 35 cubic meters of water.
The whiteness of snow, praised for centuries, is a consequence of the 95 percent air content in snowflakes. Light is scattered from the countless surfaces of ice crystals, which are snowflakes, in all directions, regardless of the wavelength of the spectrum. In general, snow plays a huge role in the thermoregulation of the Earth's climate: it reflects up to 90% of the sun's rays. It was with the onset of snowfalls and the appearance of snow-covered surfaces that the earth's atmosphere of the ancient Earth, heated by volcanoes, began to cool to its modern state. Want to know what a planet without snow looks like? Look at Venus...
But perfectly white snow can turn into any color, depending on what component is present in the water droplets: dust, sand, algae, etc. The chronicle of humanity, from chronicles to YouTube videos, talks about snow in a wide variety of color shades. You can imagine the horror of the Swiss when black snow fell on their heads exactly on Christmas Day 1969! Here and there in the highlands there is pink snow, colored by algae that ice worms feed on. And this snow smells like... watermelons!
If you have not only seen snow, but also wandered through it, you can be considered lucky: most of the world's population has never seen snow in person. By the way, have you noticed that the stronger the frost, the louder the snow creaks under your feet? This creak is the essence of the crunch of breaking ice needles on snowflakes. At temperatures below -6 degrees, there is a high-frequency component in the spectrum of this crunch. What’s interesting: snowflakes also make high-frequency sounds when they simply fall into the water. This “singing” is inaudible to the human ear, but, according to scientists, fish cannot stand it.
Every person who has devoted his life to the study of snowflakes can consider that he did not live it in vain. The first, by the way, was not a scientist, but a professional photographer, American Wilson Bentley. Snowflakes interested him as a teenager. But Bentley did not have time to sketch them: the snowflakes quickly melted even at sub-zero temperatures. Fortunately, cameras had already appeared by this time. After much experimentation, the first photograph of a snowflake on black velvet was taken on January 15, 1885. During his life, Bentley took more than 5 thousand such photographs, together with the scientist Perkins, he was the first to declare that no two snowflakes are alike, and deservedly received the nickname Snowflake.
Bentley and Perkins were right. The process of crystallization of water droplets is unpredictable, and therefore no two snowflakes with the same pattern exist. Some physicists, deriving complex formulas, prove that the number of variations in snowflake shapes exceeds the number of atoms in the human-observable part of the Universe! Their sizes also vary. The average snowflake is no more than 5 mm in diameter. But on January 28, 1987, in Fort Coy (Montana, USA), during a snowfall, one of the heirs of the Bentley business discovered, without exaggeration, a giant 38-mm snowflake!
You may ask, “Why study snowflakes? Does this make any sense? After all, four centuries have passed since Johannes Kepler, in his treatise “On Hexagonal Snowflakes,” believed the wonders of nature to be rigid geometry. Eat.
The crystal theory, which has been significantly supplemented by the study of snowflakes, has many gaps. For example, scientists know that the growth of a snowflake depends on temperature, air humidity and other external conditions. But they couldn’t explain it. For now.
But snowflakes as a type of solid precipitation are included in the classification of the International Commission on Snow and Ice. It turns out that snow crystals can be in the form of plates, star-shaped, simple columns, tipped columns, needles, spatial dendrites and even irregular shapes. The latter happens when a drop of water freezes to a falling “young” snowflake.
But in Japan, not only are all the snowflakes correct, but they are also special. That is, Japanese. Jokes aside: on the Japanese islands it is still suspected that the local snow is not the same as in other countries. What kind of jokes are there! In the early 1980s, things came to a point where the government restricted the import of skis under the pretext of protecting domestic producers. In some places in Japan on New Year's Eve you can still hear a song about a Japanese champion who will never be able to ride on Japanese snow on imported skis...