Children's project "Why is snow white?". What is snow, how are snowflakes formed? Why does the snow creak underfoot Why is the snow white

Snow is a sign real winter. It is formed when small raindrops freeze. Fluffy White snow- a real miracle. Children make snowmen out of it, play snowballs with them, and northern peoples build their houses out of snow. A thick layer of snow warms the earth. It does not allow frosty air to reach it, and maintains a positive temperature in the depths of the soil.

What is snow and how is it formed?

In scientific terms, snow is a species precipitation. This means that snow falls from the sky in the form of frozen rain. Snow is cold, white and fluffy. It consists of individual snowflakes that look like six-pointed stars. I wonder how snow is formed?

The first condition for the appearance of snow is cold. The temperature at which water turns into ice is 0ºC. When it gets cold outside, the water in puddles and lakes becomes covered with ice (freezes). In the sky at this time freeze rain clouds. Raindrops turn into snow.

The second way snow is formed is scientifically called evaporation. Hear how it goes. If you wash clothes and hang them outside in winter, the wet sheet will first freeze and become hard. After a few days, the sheet will turn into a soft, dry cloth. What happened? First, the water in the sheet turned to ice. It happened pretty quickly. Then the ice began to evaporate: small microscopic pieces of ice broke off the sheet and rose into the sky. These ice floes were so small that, looking at the drying sheet, we did not notice their flight.

Why is it snowing?

Many small ice floes are found in the heavenly heights. There they gather in a snow cloud. There are so many snowflakes in a cloud that they join together in several pieces. A few small ice stars form a large snowflake, which becomes too heavy and falls down. This is how the snow starts.

In order to form a large snow cloud, one wet sheet is not enough. Many tiny pieces of ice rise into the sky from a frozen lake, puddle or river. There they gather in large snow clouds.

The wind can carry such a cloud far. For example, where there is no frost. Thanks to the wind, snow can fall even in places where lakes and rivers have not yet frozen.

How are snowflakes formed?

Have you ever seen a snowflake under a microscope? It looks like a six pointed star. Each end of the asterisk consists of a white branch on which small white twigs grow.

These branches are scientifically called crystals. They intersect in the middle of the snow star. Each snowflake begins to grow from the center - from the place where the snow branches intersect. The growth of a snowflake is similar to the growth of a tree: six trunks grow from the center, on each of which branches begin to grow. Stars can have different branches (long or short, thick or thin), but always only 6 large branches grow in a snow star.

When water in a river or puddle freezes, ice is formed. The stars in the ice are located close to each other. When the fog or cloud freezes, the stars are located at some distance from each other. If there are too many stars, they are connected in several pieces and fall down. So the snow falls out of the clouds and covers the roads, houses and fields. Falling snowflakes adults call snowfall.

Why does the snow creak underfoot?

If there is a slight frost on the street (-2 or -3 ºС), then there is a lot of water in the fallen snow. They say about such snow that it is “wet”. It is easy to make snowballs and a snowman out of wet snow, to build "fortresses".

When the frost gets stronger (the air temperature drops to -5 or -10 ºC), the snow freezes harder and becomes dry. It is impossible to make a snowman out of dry snow, but it creaks loudly underfoot. Why does dry snow creak?

Each snowflake is like a small star. If we step on the snow, the branches in the icy snowflakes break. So when breaking many snowflakes, a crunch and creak is formed.

Snow creaks with any pressure:

• if it was stepped on;
• went on skis;
• rode on sleds.

Snow stops creaking only when it becomes almost warm (air temperature approaches 0ºC). Or when he was heavily rolled (this happens on the hills, where the snow rolls and turns into ice).

When the snow creaks very loudly?

Snow can squeak louder or quieter. When does the crunch of snow get very loud?

This happens in extreme cold. For example, in the far north at -50ºC, the crunch of snow becomes so loud that it can be heard on the next street.

With warming, when the air temperature approaches 0ºC, the crunch disappears completely. Snowflakes become soft, drops of water appear on their icy branches, which prevents the icy stars from creaking.

Scientists conduct curious experiments with frozen water. It turns out that water hears us and reacts differently to gentle and rude words. That's what the next video is about.

Snow makes winter white, it seems to hide the darkness and dirt of autumn, which is why it brings so much joy. Children especially love it. For them, snow is one of the main winter funs. Children make fortresses and snowmen out of it, ski and sled on it, or just wallow in it for hours without a visible goal. It is no wonder that there comes a time when the kids begin to ask their parents why the snow is white.

The nature of light and its role

To answer this question exhaustively and in an accessible way, adults must have some knowledge about light, color perception and snow. But you need to start with visible light. Everything around is permeated with electromagnetic waves, but people are able to see only a tiny fraction of them. The visible part of the spectrum consists of wavelengths from 550 to 630 nanometers.

Anything outside this narrow spectrum remains invisible to the human eye. True, the waves can be felt by other senses, for example, ultraviolet cannot be seen, but it warms the skin and can even burn it if you stay on a sunny beach for a long time.

Vision is a priceless gift of nature, thanks to which people have the opportunity to create a stable picture of being and to know the world. However, without light, human vision becomes a useless tool. This is easy to show to a child by entering a room where there are no windows, such as a bathroom. While the light is on, objects around are visible, their colors are distinguishable. But as soon as the light bulb goes out, the room plunges into impenetrable darkness, all things and colors cease to exist for vision, until they are again illuminated by the sun, a living fire or an electric light bulb.

Children always look forward to winter. Making a snowman, sledding and jumping into snowdrifts is interesting and enjoyable! After active games fresh air, they often find inspiration, and questions begin: “Why is the sun yellow and snow white”? Few people explain the reasons for these phenomena to the little “why”s. Let's answer at least one of the above questions. So why is snow white?

A short excursion into physics

The earth is surrounded electromagnetic waves. They are everywhere, but mostly invisible to living beings. What the eye perceives is considered a color - electromagnetic radiation, a wave that gives color sensation. The main source of electromagnetic waves is the Sun. Its rays include all primary colors:

• red;
• yellow;
• blue;
• blue;
• green;
• orange;
• violet.

If all the colors merge together, a white tint is formed, and the sun's rays are just white color.

Every object on earth transmits (reflects, absorbs) sunlight. There are those who fully display it, such as ice. Each individual snowflake is the same ice.

Interesting Snow Facts:

• Half of the inhabitants the globe I have never seen real snow, only in pictures.
• In 1949, in the Sahara for the first and last time snow. The snowfall continued for more than half an hour.

snow and color

Snowflakes fall on the ground randomly, and as a result, the snowball does not transmit fully electromagnetic waves (sunlight). Therefore, if you make a dent in a snowdrift in sunny weather, the snow appears green-yellow. When overcast, it looks blue. If there is a bright red sunset in the sky - pink. The surface of the snowdrift displays all the colors of the rainbow when it is clear and sunny outside.

In latitudes that are closer to the Earth's poles, the snow appears to be a rich red color. Scientists often note a similar phenomenon in the Arctic. In the United States, namely the state of California, in 1955, residents observed a green snowfall. In 1969, a black snowfall hit Switzerland. In Russia, yellow snow fell in 2015, which was written about for a long time in the media. air masses brought with them African sand dust, which painted precipitation in an unusual color for them.

Interesting Snow Facts:

• There are no two identical snowflakes, each has its own separate pattern. Physicists claim that there are more such patterns than there are atoms on Earth.
• World Snow Day is celebrated annually on January 19th.

That there is snow different color, made a note in the diary of the great Charles Darwin. It is known that once the writer went on a trip, and noticed that the horses left red tracks in the snowdrifts. It was a bright sunset, so the snow seemed not white, but pink.
The concept of color is generally subjective. One sees grass as green, another sees light green, and the third sees turquoise. These phenomena are not yet fully understood.

So, the answer to the main question: “Why is snow white?” It reflects the sun's rays, which, as already mentioned, are white. But it's worth intervening somehow weather events- clouds, a bright sunset, and these atmospheric precipitation will no longer seem to be of such a shade.

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When a Russian person is asked to imagine winter, the first thing he sees in his imagination is snow, a snow-white cover that has enveloped everything around. We are so used to the color of snow that we don’t even think about why snow is white.

Why is snow white

All the colors we perceive are dependent on the rays of the sun. Black objects completely absorb sunlight, and therefore are perceived by us as black. And if the object completely reflects a ray of the sun, then the color will appear white to us.

What is snow, exactly? This is frozen water, hexagonal pieces of ice. Water and ice are colorless. Why is snow white then? The ice remains colorless, as it passes the entire sunbeam through itself. And each snowflake would pass all the light through itself and would also have no color. But snowflakes usually fall on top of each other in erratic motion. And already together they become opaque, but white.

To understand why snow is white, why it reflects the rays of the sun, we need to look at the composition of snow. Snow is formed from snowflakes, and snowflakes are formed from a huge number of crystals. These crystals are not smooth, but with edges. This is the answer to our question why snow is white. It is from the edges that sunlight is reflected.

The water in the atmosphere is steam, it freezes and transparent crystals form. From the movement of air, the crystals move freely up and down. In this chaotic movement, the crystals are connected to each other. And when at last too many crystals gather together, then they begin to fall to the ground already in the form of snowflakes familiar to us.

It turns out that the color of snow is white, because the light of the sun that it reflects is also white. Think if a ray of the sun turned green or yellow, then the color of the snow would be the same. Surely, many have noticed that during sunrise or sunset, it seems to us that the rays of the sun become pinkish, so the snow at this moment seems pink to us.

Is there a different color of snow

Who can give an affirmative answer to this absurd question?! Don't dismiss this idea right away. In fact, it also happened that colored snow fell. For example, once Charles Darwin described one such case. It happened during one of his expeditions. Looking at the hooves of the mules, C. Darwin saw that they were covered with red spots. It happened when the mules walked through the fallen snow. It turned out that the red snow was formed from the presence of red pollen in the air at the time when the snow began to fall.

When thinking about winter, a snow-white cover always appears in the imagination, enveloping everything around, and rarely does anyone think about why it is white.

Droplets of water in the atmosphere, at sub-zero temperatures, freeze and turn into ice, falling to the ground in the form of snow. Ice is water in a solid state, it is transparent in itself. Then why is snow white?

Snowflakes also have no color, but if you look at them through a magnifying glass, you can see that they look like crystals, resembling a regular hexagon with edges in their shape. During a snowfall, it is the edges of the snowflakes that reflect the light rays that give the snow its usual white color.

On the ground, snow cover is a cluster of snowflakes located very tightly to each other in a chaotic manner. Together they reflect light from greater strength, so even at night, when the surface is not illuminated by the sun, we see the snow as white. The source of light rays at night are the moon, stars, lanterns.

However, the reason for the "whiteness" of the snow cover lies not only in the ability of the faces of ice crystals to reflect the light falling on them, but also in the purity of their surface. The bottom line is that no snowflake can be perfectly transparent. In the atmosphere, water droplets mix with various particles (dust, industrial emissions and other pollutants) that are able to absorb unreflected light rays.

Why does snow glitter?

In this case, the well-known law applies: the angle of incidence equal to the angle reflections. Billions of microcrystals, having the shape of a regular hexagon, absorb the sun's rays, refract them, and then reflect in different directions and at different angles, like "sunbeams". Therefore, we see how snowflakes sparkle and shimmer in the sun.

Why do snowflakes crunch and creak underfoot?

Walking through the snow, you can often hear a crunch or creak under your feet. Such a sound is obtained because the crystals of snowflakes rub against each other under mechanical pressure and break. However, this phenomenon can not always be observed, but only at a certain air temperature.

The fact is that snow creaks only at temperatures from 2 to 20 degrees below zero, and in different temperature ranges, creaking and crunching are accompanied by a special sound. This is explained by the fact that in hard frost snowflake crystals become denser and stronger, and at a temperature of 0 ° C and above, the snow cover loses its strength and begins to melt.

In fact, even the break of one small snowflake is accompanied by sound. But this sound is so weak that the human hearing organs simply do not perceive it. While trillions of snowflakes are breaking, the sound becomes much stronger and a person can clearly hear the characteristic crackling of snow.