Explain why snow creaks to a preschooler. What is snow and why is it white? Why is snow white?
How is snow created?
Snow is a lot of beautiful sparkling snowflakes that fall from a height to the ground.
In winter, the wind drives clouds onto our land from the warm oceans and seas. Above the ground, when clouds cool, small crystals form in them, and new particles of steam settle and cool on their surface, which turn into new ice crystals. This hexagonal crystal constantly grows, develops and finally becomes an amazingly beautiful snowflake that we admire during a snowfall.
Why snow white?
If we look at a snowflake, at this little star through which a ray of sunlight passes, we will notice that it is colorless. Then why is snow white if it consists of snowflakes? Because when it snows, snowflakes randomly fall on top of each other, lie in a homogeneous mass and become opaque, since they cannot completely transmit the sun's rays through them. And the sun's ray is white, which is why we see snow as dazzling white.
Why does snow squeak underfoot in cold weather?
The fact is that each snowflake is a small crystal. When you step on snow, the mass of these crystals compresses, rubs against each other and breaks. When the frost is light, when you step on the snow, the snowflakes-crystals shrink, but at the same time, some of the snowflakes melt and turn into water. Water becomes a kind of lubricant for the remaining crystals, and they do not creak. But in severe frost The melting of the snowflakes does not occur and the creaking of snow is heard - the noise from crushed snow crystals. Moreover, the stronger the frost, the higher the sound.
(From the "First Encyclopedia of Little Whys")
Card with snowflakes
And now, my friend, let’s make a card with a snowflake and give it to grandma.
Mom herself can cut out a snowflake,
and glue the baby onto the blank.
Ready!
Happy Second Sunday of Advent, friends!
Christina,
club "Developing Homes"
Children are able to greatly puzzle parents and other adults with questions: “Why is the sky above us blue?”, “Why is the sun shining?”, “Why is the river flowing?”... In winter, their favorite children's question: “Why is the snow white, crunches and creaks underfoot?” And it’s worth dealing with this interest right away, since this winter is not the last, and if you hush up the issue now, it will arise before parents in just a year.
Snow color
We’ll figure out why the snow crunches underfoot a little later; let’s first decide on the first part of the question. Children who are ripe for it already know that snow is frozen water, that is, ice. Ice is transparent and therefore colorless, so why is snow white?
If you catch a snowflake and look closely at it, it is not difficult to see that it is also mostly transparent. It acquires color only when its edges reflect light - no matter whether it is sunny or artificial. And if the snowflakes were neatly stacked, they would seem transparent, except that the edges would be painted - the color of the sky or the nearest advertising billboard. However, the snow falls randomly, the edges are exposed to the sun at different angles, reflect and refract it, again chaotically. As a result, the eyes perceive a freshly falling snowdrift as perfectly white (of course, if there are no clouds in the sky).
When the snow crunches
Now it remains to find out why the snow creaks underfoot. Keeping in mind that snowflakes are pieces of ice, the answer to this question is not too difficult. The ice crystals that they are are quite fragile, although they are hard. When pressure is applied to them (for example, under the weight of a person walking in the snow), the snowflakes collapse, producing a barely audible crunch. It is accompanied by the same almost (but only almost!) silent creaking from the friction of tiny pieces of ice one against the other. If only one snowflake broke, the human ear would not be able to hear such a small sound. However, there are tens of thousands, or even millions, of them - and the creaking crunch becomes audible. In addition, very thin connections-bridges appear between individual snowflakes in a snowdrift due to frost, invisible to the eye, but adding their own note to the noise.
When the snow doesn't creak
The offspring are not always satisfied with the answer: either they consider it abstruse, or it does not coincide with their vision of the world. However, much more often the following questions arise, logically following from your explanations: “Then why does the snow crunch under your feet in cold weather, but when it’s not very cold, it doesn’t?” First of all, because snowflakes with slight cold become more flexible, elastic and do not break immediately - many manage to melt under pressure. There is also no friction between individual crystals - it is “lubricated” by water, which does not have time to freeze. And bridge-layers don’t form either, so there’s nothing to burst. Accordingly, the question: “Why does the snow crunch underfoot” will not arise for a child walking next to you. True, only until the next cold snap!
However, parents who have explained why the snow crunches under their feet and have wiped the sweat from their foreheads with relief should not relax. Very soon their child will make them happy next question- and who knows how successfully it will be answered.
Snow is a type of precipitation characteristic of a certain season of the year. It forms high in the clouds. Tiny particles of water collect around microscopic dust particles and then freeze. The resulting micro-ice flakes initially do not exceed 0.1 mm in diameter. As they fall down, they grow, expanding their body due to the condensation of air and moisture on their parts. The size and lace of falling snowflakes depends on the height and temperature of the cloud from which they formed. But why in cold weather does the snow creak under your feet?
To understand why snow creaks underfoot, you first need to understand the structure of a snowflake.
Snowflake structure
The molecular structure of water is designed in such a way that in the formation of a snowflake the angles can only be 120 and 60 degrees. New crystalline growths form on the edges and tops of the snowflake, and the next layers freeze on top of them. As a result of these processes, various amazing forms are born, but almost all resemble the shape of a star.
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Why does snow melt faster in the city than outside the city?
Basic shapes of snowflakes
Scientists have identified several basic forms of snowflakes:
- The needle is a crystal that resembles a long knitting needle made of ice, sometimes it is hollow, and the ends branch into several growths;
- Star - the formation resembles a weaving structure of ice fibers. The fibers are usually arranged in random branching;
- Dendrites - are formed when snowflake crystals grow together, forming symmetrical branched growths;
- Fluffy - snowflakes that have lost some parts along the way or broken completely. This happens for several reasons, one of them is strong wind;
- Column - large flat snowflakes, are the most common, resembling the shape of a column or pencil, usually hexagonal, pointed at the end;
- Plate – come in the form of a petal, which is divided into sectors by ice ribs.
What determines the shape of snowflakes?
Among these groups there are 48 various types formation of snowflakes. The shape of snowflakes directly depends on the environmental conditions in which they are formed. First of all, the silhouette of a snowflake is affected by temperature; the cloud is colder the higher it is. If the temperature of the cloud is relatively high - 30 to 0, then the formation of a snowflake will resemble a hexagon with flat body. At temperatures from – 5 to – 3 degrees, snowflakes resemble needle-shaped crystals. From – 8 to – 12, the shape again resembles a flat hexagon, and at temperatures from – 13 to – 16, snowflakes are formed in the form of crystalline stars.
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Why is snow white?
Why does the snow squeak?
As described above, snow is a formation of various small crystals. In the body of a snowflake, among the crystals, there is also air. When a certain amount of snow is compressed, it becomes denser, the entire composition of the air is displaced, and the crystals of the snowflakes break against each other. P When friction and fracture occurs, the crystal produces a sound, which is perceived by the human ear as a crunch or creaking. This noise is not always heard.
When thinking about winter, white always appears in the imagination snow cover, enveloping everything around, while rarely anyone thinks about why it is white.
At sub-zero temperatures, droplets of water in the atmosphere freeze and turn into ice, falling to the ground as snow. Ice is water in a solid state and is itself transparent. Then why is snow white?
Snowflakes also have no color, but if you look at them through a magnifying glass, you will notice that they look like crystals, reminiscent of a regular hexagon with edges in their shape. During a snowfall, it is the edges of snowflakes that reflect light rays that give the snow the white color we are accustomed to.
On the ground, snow cover is a cluster of snowflakes located very close to each other in a chaotic manner. Together they reflect light with greater force, so even at night, when the surface is not illuminated by the sun, we see snow as white. The source of light rays at night is the moon, stars, and lanterns.
However, the reason for the “whiteness” of the snow cover lies not only in the ability of the edges of ice crystals to reflect the light falling on them, but also in the cleanliness of their surface. The point is that no snowflake can be perfectly transparent. In the atmosphere, water droplets mix with various particles (dust, industrial emissions and other pollutants), which are capable of absorbing non-reflected light rays.
Why does snow shine?
In this case, the well-known law applies: the angle of incidence equal to angle reflections. Billions of microcrystals, shaped like a regular hexagon, absorb Sun rays, refract them, and then reflect them in different directions and at different angles, like “sunbeams”. That's why we see how snowflakes sparkle and shimmer in the sun.
Why do snowflakes crunch and squeak underfoot?
While walking in the snow, you can often hear crunching or squeaking under your feet. This sound is produced because the snowflake crystals rub against each other under mechanical pressure and break. However, this phenomenon cannot 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 the creaking and crunching are accompanied by a special sound. This is explained by the fact that in severe frost the crystals of snowflakes become denser and stronger, and at temperatures of 0 ° C and above, the snow cover loses its strength and begins to melt.
In fact, even the breaking of one small snowflake is accompanied by sound. But this sound is so weak that the human hearing organs simply do not perceive it. As trillions of snowflakes break, the sound becomes much stronger and a person clearly hears the characteristic crackling of snow.