How is a snowflake born? The whole truth about snowflakes Interesting !? Click here. Why do all snowflakes have one very strange feature - they are all hexagonal

The snowflake is one of the most beautiful creatures of nature. We would have to work hard to create a shape that is comparable in beauty to the shape of a snowflake. In the snow, millions of snowflakes fall to the ground, and no two of them are alike.

Snow, as you already know, is just frozen water. Why then is the snow white if it is frozen water? It should be colorless. Snow is white because the planes of the snowflake, which are ice crystals, reflect light, so the snow appears white.

Crystals are formed when water freezes. This means that the molecules are arranged in a special order, forming geometric shape, which we call "crystal".

It so happened that a water molecule consists of three particles - two hydrogen atoms and one oxygen atom. Therefore, during crystallization, it can form a three- or hexagonal shape. Water turning into snow is a form of water vapor in the atmosphere. When freezing, the water crystals are so small that they are not visible. When snow forms, these crystals move up and down by air currents in the atmosphere.

During such movements, they are grouped around the smallest particles of dust or water droplets. Such a group of crystals is getting larger and larger, around one such core can gather several hundred such crystals.

This group grows large and heavy and falls to the ground. We call it a "snowflake". Some snowflakes are up to three centimeters in diameter. The size of the snowflakes depends on the temperature. The lower the temperature, the smaller the snowflakes.

To understand why snowflakes look so beautiful, it is necessary to consider the life history of one snow crystal.

Ice snowflakes in a cloud are formed at -15 degrees due to the transition of water vapor to a solid state. The basis for the formation of snowflakes are small dust particles or microscopic ice floes, which serve as a nucleus for condensation of water molecules on them. The nucleus of crystallization is where the formation of snowflakes begins.

More and more water molecules attach to the growing snowflake in specific places, giving it a distinct hexagon shape. The key to the structure of solid water lies in the structure of its molecule, which can be simply imagined as a tetrahedron - a pyramid with a triangular base in which angles of only 60 ° and 120 ° are possible. There is oxygen in the center, in two vertices - for hydrogen, more precisely - for a proton, the electrons of which are involved in the formation covalent bond with oxygen. The two remaining vertices are occupied by pairs of oxygen valence electrons, which do not participate in the formation of intramolecular bonds, which is why they are called lonely.

The snowflake is a single crystal of ice, a variation on the theme of a hexagonal crystal, but it grew quickly, in non-equilibrium conditions. Under some conditions, ice hexagons grow vigorously along their axis, and then elongated snowflakes are formed - snowflake-columns, snowflakes-needles. In other conditions, hexagons grow mainly in directions perpendicular to their axis, and then snowflakes are formed in the form of hexagonal plates or hexagonal stars.

A drop of water can freeze to a falling snowflake - as a result, snowflakes are formed irregular shape... The widespread belief that snowflakes necessarily look like hexagonal stars is erroneous. The shapes of the snowflakes are very diverse.

Astronomer Johannes Kepler in 1611 wrote a whole treatise "On Hexagonal Snowflakes." In 1665, Robert Hooke saw with a microscope and published many drawings of snowflakes herself different shapes... The first good photo snowflakes under a microscope were made in 1885 by the American farmer Wilson Bentley. The most famous followers of the Bentley case are Ukihiro Nakaya and the American physicist Kenneth Libbrecht. Nakaya was the first to suggest that the size and shape of snowflakes depend on the air temperature and moisture content in it, and brilliantly confirmed this hypothesis experimentally, growing ice crystals of various shapes in the laboratory. And Libbrecht at his California Institute of Technology and to this day is busy growing snowflakes all day. Scientist, together with photographer Patricia Rasmussen, are planning to publish a book, which will include the most photogenic snowflakes, some of which can already be seen on his website SnowCrystals.com.

There is another secret inherent in the structure of the snowflake. In it, order and chaos coexist together. Depending on the preparation conditions, a solid must be either in a crystalline state (when the atoms are ordered) or in an amorphous state (when the atoms form a random network). Snowflakes, on the other hand, have a hexagonal lattice, in which oxygen atoms are arranged in an orderly manner, forming regular hexagons, and hydrogen atoms are arranged chaotically. However, the relationship between the structure crystal lattice and the shape of a snowflake, which is ten million times larger than a water molecule, is not obvious: if water molecules were attached to the crystal in a random order, the shape of the snowflake would turn out to be irregular. It's all about the orientation of molecules in the lattice and the arrangement of free hydrogen bonds, which contributes to the formation of even faces.

Water vapor molecules are more likely to fill voids than stick to flat edges, because voids contain more free hydrogen bonds. As a result, the snowflakes take the form of regular hexagonal prisms with smooth edges. Such prisms fall from the sky, with a relatively low air humidity in a variety of temperature conditions.

Sooner or later, irregularities appear on the edges. Each tubercle attracts additional molecules and begins to grow. The snowflake travels through the air for a long time, while the chances of meeting new water molecules at the protruding tubercle are slightly higher than at the edges. So rays grow very quickly on the snowflake. One thick ray grows out of each face, since molecules cannot tolerate emptiness. Branches grow from the tubercles formed on this ray. During the travel of a tiny snowflake, all of its edges are in the same conditions, which serves as a prerequisite for the growth of the same rays on all six edges. In ideal laboratory conditions, all six directions of the snowflake grow symmetrically and with similar configurations. In the atmosphere, most of the snowflakes are irregular crystals; only some of the six branches can be symmetrical.

Nowadays, the study of snowflakes has become a science. Back in 1555, the Swiss explorer Mangus made sketches of the shapes of snowflakes. In 1955, the Russian scientist A. Zamorskiy divided snowflakes into 9 classes and 48 types. These are plates, needles, stars, hedgehogs, columns, fluffs, cufflinks, prisms, group. The International Commission on Snow and Ice adopted a fairly simple classification of ice crystals in 1951: plates, star crystals, columns or columns, needles, spatial dendrites, tipped columns, and irregular shapes. And three more types of icy precipitation: fine snow grains, ice grains and hail.

In 1932, nuclear physicist Ukihiro Nakaya, a professor at the University of Hokkaido, started growing artificial snow crystals, which made it possible to compile the first classification of snowflakes and reveal the dependence of the size and shape of these formations on temperature and humidity. In the city of Kaga, located on the western coast of the island of Honshu, there is the Museum of Snow and Ice, founded by Ukihiro Nakaya, which now bears his name, symbolically built in the form of three hexagons. The museum has a snowflake machine. Nakaya identified 41 individual morphological types among snowflakes, and meteorologists S. Magano and Xu Li in 1966 described 80 types of crystals.

Under certain conditions, in the absence of wind, falling snowflakes can adhere to each other, forming huge snowflakes. In the spring of 1944, flakes up to 10 centimeters across, like spinning saucers, fell out in Moscow. And in Siberia, snow flakes were observed with a diameter of up to 30 centimeters. The largest snowflake was recorded in 1887 in Montana, USA. Its diameter was 38 cm, and its thickness was 20 cm. This phenomenon requires complete calmness, because the longer the snowflakes travel, the more they collide and adhere to each other. Therefore, at low temperatures and strong wind snowflakes collide in the air, crumble and fall to the ground in the form of fragments - "diamond dust". The likelihood of seeing large snowflakes increases significantly near water bodies: evaporation from lakes and reservoirs is excellent construction material.

The ice that forms a snowflake is transparent, but when there are many of them, sunlight, reflecting and scattering on numerous faces, gives us the impression of a white opaque mass - we call it snow. The snowflake is white because the water absorbs the red and infrared part of the light spectrum very well. Frozen water largely retains the properties of liquid water. Sunlight, passing through a layer of snow or ice, loses red and yellow rays, which are scattered and absorbed in it, and light bluish-green, blue or bright blue passes through - depending on how thick the layer was in the path of the light ...

FACTS
Snowflakes form - a snow cover that reflects up to 90% of sunlight into space.
In one cubic meter of snow there are 350 million snowflakes, and throughout the Earth - 10 to 24 degrees.
The weight of the snowflake itself is only about a milligram, rarely 2 ... 3. Nevertheless, by the end of winter, the mass of the snow cover of the northern hemisphere of the planet reaches 13,500 billion tons.

By the way, the snow itself is not only white. In arctic and mountainous regions, pink or even red snow is common. This is due to the algae living between the crystals. But there are cases when snow fell from the sky already painted. So, on Christmas 1969, black snow fell on the territory of Sweden. Most likely, it is soot absorbed from the atmosphere and industrial pollution. In 1955, phosphorescent green snow fell near Dana, California, claiming several lives and causing serious harm to the health of residents who risked trying it on their tongues. Arose different versions this phenomenon, even the atomic tests in Nevada. However, they were all rejected and the origin of the green snow remained a mystery.

Fresh snow on a frosty day is always accompanied by a cheerful crunch underfoot. This is nothing more than the sound of crystals breaking. And snowflakes also clear the air from dust and burning, so it is easy to breathe during a snowfall.

Why do all snowflakes have one very strange feature - they are all hexagonal. The famous Johannes Kepler, the astronomer who discovered the laws. " the movement of the planets. And he approaches the simple “snowy” question like a real scientist and devotes to him the scientific work “On Hexagonal Snowflakes”. In search of the "active principle", Kepler examines and compares the shapes of honeycombs and pomegranate seeds, cuts of plant stems and the shape of flowers. It would seem that these objects of study are not related to winter snow, but the scientist sees the harmony of the surrounding world in the interconnection of all its elements. Moreover, he discovers the connection of these forms with the "divine proportion" (the proportion of the "Golden Section") and with the Fibonacci numbers. Shall we continue?

Snowflake Bentley Wilson A. Bentley, amazing self-taught farmer from Vermont (USA), nicknamed "Snowflake" (Snowflake Man). In 1885, when he was 20 years old, after numerous unsuccessful attempts, Wilson finally took the first photograph of a snowflake that struck him in such a way, attaching a large folding camera to a microscope. From that moment on, Wilson Bentley did not let go of the camera. 46 years old, Bentley collected a unique collection of photographs of snowflakes. By the end of Bentley's life, the collection numbered over 5,000 pieces. Surprisingly, no snowflake shape is repeated. There are similar snowflakes, but absolutely no identical ones!

In the Eskimo language, there are more than 20 words for snow. There are about 70 in the Yakut language. They have 50 different words to indicate the colors of the snow. The Eskimos have 28 words for snow. And in the language of the Eskimos, there are 14 definitions of snow. The Eskimos have 150 words for snow. He is their whole life for them. Therefore, spring snow is called differently than winter snow.

Snow is formed when water in the atmosphere freezes over as vapor. The vapor freezes to form clear, transparent crystals. The movement of air causes these crystals to fly up and down. Snow is white because snowflakes are crystals that reflect the entire spectrum of light that we see. Further

In Siberia, snow flakes reached 30 centimeters in diameter. Such giants can only drop out when there is complete calm. In low temperatures and strong winds, snowflakes collide in the air, crumble and fall to the ground in the form of debris. At a frost of 40 degrees, the nascent ice crystals fall out in the form of "diamond dust". In Yakutia, in clear frosty weather, thin ice needles fall out.

The hexagonal shape of the snowflakes is explained molecular structure water, but the question why the snowflakes are flat has not yet been answered. Some snowflakes are up to three centimeters in diameter. The size of the snowflakes depends on the temperature. The lower the temperature, the smaller the snowflakes. In some parts of the planet, there was colored snow: blue, green, red and even black? This is due to the presence of a certain fungus or dust in the air where snowflakes are formed.

Comments to. X. n. O. V. Mosina.

Why elementary ice crystals are hexagonal is easy to understand when analyzing the structure of crystalline water - ice.

In a water molecule, two electron pairs form polar covalent bonds between hydrogen and oxygen atoms, and the remaining two electron pairs remain free and are called unshared.

Rice. Water molecule

Since the oxygen atom has more electrons (chemists say that the oxygen atom is more electronegative) than the hydrogen atom, the electrons of the two hydrogen atoms are shifted towards the more electronegative oxygen atom, causing the two positive charges of the hydrogen atoms to be compensated by the equal size of two atoms. hydrogen is the negative charge of the oxygen atom. Therefore, the electron cloud has a non-uniform density. There is a lack of electron density near the hydrogen nuclei, and an excess of electron density is observed on the opposite side of the molecule, near the oxygen nucleus. This leads to the fact that the water molecule is a small dipole containing positive and negative charges at the poles. It is this structure that determines the polarity of the water molecule. If we connect the epicenters of positive and negative charges with straight lines, we get a volumetric geometric figure is a regular tetrahedron.

The unit cell of water is tetrahedra containing five H2O molecules linked by hydrogen bonds. In this case, each of the water molecules in simple tetrahedra retains the ability to form hydrogen bonds. Due to their simple tetrahedra can be joined together by vertices, edges or faces, forming a variety of spatial structures.

Rice. In the crystal structure of ice, each water molecule participates in 4 hydrogen bonds, forming a tetrahedron

Thus, the structure of water is associated with the so-called Platonic solids (tetrahedron, dodecahedron), the shape of which is associated with the golden ratio. The water molecule also has the shape of a Platonic solid (tetrahedron).

And of all the variety of structures in nature, the base is the hexagonal (hexagonal) structure, when six water molecules (tetrahedrons) are combined into a ring. This type of structure is typical for ice, snow and melt water.

A snowflake is a complex, symmetrical structure made up of ice crystals gathered together. There are many options for "assembly" - so far it has not been possible to find two identical ones among the snowflakes. Research carried out in Libbrecht's laboratory confirms this fact - crystal structures can be grown artificially or observed in nature. There is even a classification of snowflakes, but, despite the general laws of construction, snowflakes will still slightly differ from each other, even in the case of relatively simple structures.

Rice. 1. Crystal structure of ice

So why are snowflakes hexagonal? In the crystal structure of ice, each water molecule participates in 4 hydrogen bonds directed to the vertices of the tetrahedron at strictly defined angles equal to 109 ° 28 "(while in ice structures I, Ic, VII and VIII this tetrahedron is correct). In the center of this tetrahedron there is an oxygen atom, in two vertices - a hydrogen atom, the electrons of which are involved in the formation of a covalent bond with oxygen. The two remaining vertices are occupied by pairs of oxygen valence electrons, which are not involved in the formation of intramolecular bonds. Now it becomes clear why the ice crystal is hexagonal.

The main feature that determines the shape of the crystal is the connection between water molecules, similar to the connection of links in a chain. In addition, due to the different ratios of heat and moisture, crystals, which in principle should be the same, acquire different shape... Colliding on its way with supercooled small droplets, the snowflake is simplified in shape, while maintaining symmetry.

But why do elongated snowflakes sometimes form? A snowflake is a single crystal of ice, an analogue of a hexagonal crystal, but it grew quickly, in non-equilibrium conditions. Under some conditions, ice hexagons grow vigorously along their axis, and then elongated snowflakes are formed - snowflake-columns, snowflakes-needles. In other conditions, hexagons grow mainly in directions perpendicular to their axis, and then snowflakes are formed in the form of hexagonal plates or hexagonal stars.

Read more about snowflakes and the processes of their formation in the article by Sergey Apresov "White Magic":

K. x. n. O. V. Mosin

WHY ARE THE SNOWFLAKES HEXAGONAL?

To understand why snowflakes look so beautiful, it is necessary to consider the life history of one snow crystal.

Ice snowflakes in a cloud are formed at -15 degrees due to the transition of water vapor to a solid state. The basis for the formation of snowflakes are small dust particles or microscopic ice floes, which serve as a nucleus for condensation of water molecules on them. The nucleus of crystallization is where the formation of snowflakes begins.

More and more water molecules attach to the growing snowflake in specific places, giving it a distinct hexagon shape. The key to the structure of solid water lies in the structure of its molecule, which can be simply imagined as a tetrahedron - a pyramid with a triangular base in which angles of only 60 ° and 120 ° are possible. In the center there is oxygen, in two vertices - for hydrogen, more precisely - for a proton, the electrons of which are involved in the formation of a covalent bond with oxygen. The two remaining vertices are occupied by pairs of oxygen valence electrons, which do not participate in the formation of intramolecular bonds, which is why they are called lonely.

A drop of water can freeze to a falling snowflake - as a result, irregularly shaped snowflakes are formed. The widespread belief that snowflakes necessarily look like hexagonal stars is erroneous. The shapes of the snowflakes are very diverse.

Astronomer Johannes Kepler in 1611 wrote a whole treatise "On Hexagonal Snowflakes." In 1665, Robert Hooke saw with a microscope and published many drawings of snowflakes of various shapes. The first successful photograph of a snowflake under a microscope was taken in 1885 by the American farmer Wilson Bentley. The most famous followers of the Bentley case are Ukihiro Nakaya and the American physicist Kenneth Libbrecht. Nakaya was the first to suggest that the size and shape of snowflakes depend on the air temperature and moisture content in it, and brilliantly confirmed this hypothesis experimentally, growing ice crystals of various shapes in the laboratory. And Libbrecht at his California Institute of Technology and to this day is busy growing snowflakes all day. Scientist, together with photographer Patricia Rasmussen, plan to publish a book, which will include the most photogenic snowflakes, some of which can already be seen on his website. SnowCrystals.com.

There is another secret inherent in the structure of the snowflake. In it, order and chaos coexist together. Depending on the preparation conditions, a solid must be either in a crystalline state (when the atoms are ordered) or in an amorphous state (when the atoms form a random network). Snowflakes, on the other hand, have a hexagonal lattice, in which oxygen atoms are arranged in an orderly manner, forming regular hexagons, and hydrogen atoms are arranged chaotically. However, the relationship between the structure of the crystal lattice and the shape of a snowflake, which is ten million times larger than a water molecule, is not obvious: if water molecules were attached to the crystal in a random order, the shape of the snowflake would turn out to be incorrect. It's all about the orientation of molecules in the lattice and the arrangement of free hydrogen bonds, which contributes to the formation of even faces.

Under certain conditions, in the absence of wind, falling snowflakes can adhere to each other, forming huge snowflakes. In the spring of 1944, flakes up to 10 centimeters across, like spinning saucers, fell out in Moscow. And in Siberia, snow flakes were observed with a diameter of up to 30 centimeters. The largest snowflake was recorded in 1887 in Montana, USA. Its diameter was 38 cm, and its thickness was 20 cm. This phenomenon requires complete calmness, because the longer the snowflakes travel, the more they collide and adhere to each other. Therefore, at low temperatures and strong winds, snowflakes collide in the air, crumble and fall to the ground in the form of fragments - "diamond dust". The likelihood of seeing large snowflakes increases significantly near water bodies: evaporation from lakes and reservoirs is an excellent building material.

FACTS about snowflakes

Snowflakes form - a snow cover that reflects up to 90% of sunlight into space.
In one cubic meter of snow there are 350 million snowflakes, and throughout the Earth - 10 to 24 degrees.

The weight of the snowflake itself is only about a milligram, rarely 2 ... 3. Nevertheless, by the end of winter, the mass of the snow cover of the northern hemisphere of the planet reaches 13,500 billion tons.

Snow is not only white. In arctic and mountainous regions, pink or even red snow is common. This is due to the algae living between the crystals. But there are cases when snow fell from the sky already painted. So, on Christmas 1969, black snow fell on the territory of Sweden. Most likely, it is soot absorbed from the atmosphere and industrial pollution. In 1955, phosphorescent green snow fell near Dana, California, claiming several lives and causing serious harm to the health of residents who risked trying it on their tongues. There were different versions of this phenomenon, even the atomic tests in the state of Nevada. However, they were all rejected and the origin of the green snow remained a mystery.

Kenneth Libbrecht: snow under the microscope

The popularity around the world of the American Kenneth Libbrecht (Kenneth Libbrecht) brought winter, or rather such required attribute like snow. The epigraph to his work is the words of Henry David Thoreau: “The air in which they arise is filled with creative genius. I would hardly have admired more, even if real stars had fallen on my coat. " Guess what this is about? Right. About snowflakes!

Kenneth Libbrecht was born in 1958 in Fargo, North Dakota. And he is not a photographer, as it might seem at first glance, but a scientist. Kenneth is a professor of physics at the California Institute of Technology. At the beginning of his career, our hero was interested in astronomy, but his latest research is devoted to the study of the qualities of ice crystals, and especially the structure of snowflakes. It was as a supplement to Kenneth's professional research that several popular books were published, illustrated with photographs of snowflakes of a wide variety of shapes and sizes.

Most snowflakes have six-sided symmetry, although specimens with both three and twelve sides are found. But seeing a crystal with four, five or eight sides is impossible, Kenneth assures us. According to the author, the most ideal snowflakes in shape can be found when there is a small snowfall and a light wind blows, and the weather is especially cold.

The popularity of Kenneth's work is further evidenced by the fact that four of his photographs were selected by the US Postal Service for designs for the 2006 Winter Holidays stamps. The total circulation of stamps was about three billion copies.

“Every snowfall is an adventure for the photographer, because they all bring different crystals,” says Kenneth Libbrecht. "And it's true - no two snowflakes are alike." Well, if so, then we can confidently assert two things: the author is provided with work for life, and his creations can be viewed endlessly.

Photographer Yaroslav Hnatyuk -

HIV virus model -

visualscience.ru/illustrations/modelling/gripp-H1N1-interactive/

The snowflake is one of the most amazing natural creations. If a person wanted to create something like that, he would have to try very hard. During a snowfall, billions of small crystals cover the earth, and it is worth noting that none of them are alike, they are all different.

What determines the shape of a snowflake?

The shape of a snowflake depends on the temperature that contributed to its formation. Everyone knows that clouds that are high will be colder than those below. So, how temperature affects the shape of a snowflake:

-3 ... 0 ° С - flat hexagon;
-5 ...- 3 ° С - needle crystal;
-8 ...- 5 ° С - column-prism;
-12 ...- 6 ° С - again a flat hexagon;
-16 ...- 12 ° С - star-shaped snowflakes.

As it grows, the snowflake becomes heavy, causing it to fall to the ground. In the process of falling, its shape changes. If, falling, the snowflake rotates, then it will reach the ground perfectly symmetrical. And if the crystal falls sideways, then in the end it will lose its shape. On the fly, snowflakes can stick together and form whole flakes of snow. Each of them can contain up to two hundred crystals. It can be concluded that the shape of a snowflake completely depends on the trajectory of its flight and temperature regime at different heights.

Snowflake classification

In 1951, the International Commission for the Study of Snow and Ice adopted the classification of solid precipitation. All crystals, according to her, can be divided into groups:

plates;
stellate dendrites;
needles;
columns;
columns with a tip;
spatial dendrites;
formations of irregular shape.

hail;
ice crumbs;
snowy fine grains.

Description of the main types of snowflakes

Star dendrites are crystals that feature a branching, tree-like structure. They have 6 main branches, arranged symmetrically, and many branches, randomly placed. The size of such formations, as a rule, is 5 mm in diameter, and their thickness is 0.1 mm. This suggests that such snowflakes are thin and flat.
Columns are the most common form of snowflakes, also called a column. Such hollow tubes can be in the form of a hexagon, like a pencil, sharpened at the end.
The plates are composed of many ice ribs that divide the snowflake into sectors. Such formations are also very thin and flat.
The needles are columnar crystals that grow thin and long. Sometimes they are hollow inside, and sometimes they can split into several branches.

Columns with a tip are columnar, but under the influence of various factors can turn into thin plates, especially if they are brought into a zone where a different temperature prevails.
Spatial dendrites are compressed or accreted columnar crystals that have formed a three-dimensional structure. Moreover, each branch is located in a separate plane.
Irregularly shaped snowflakes are crystals that have experienced many "adventures" during the flight. For example, they could be brought into a turbulent zone, where they could lose some of the branches or completely break. Such snowflakes can be seen in strong winds in wet snow.