Why is snow white physics. Why is snow white, although an individual snowflake is transparent? Is it possible to eat snow
Marina Shkerina
Research project “Why is snow white?”
The project was completed jointly with the child.
Introduction
Winter came. It became cold outside. The whole earth, all the trees, were covered with a white fluffy blanket. White snowflakes are falling, lying on the ground, on the roofs of houses, on trees, on people. Snowflakes look like white stars. They fall quietly to the ground.
I really love looking at snowflakes. They are very beautiful. Like lace, all different. Sometimes they stick together and fall to the ground in large flakes. Sometimes a cold wind breaks the white stars, turning them into fine snow dust, and then it is very difficult to see them.
One morning I woke up and looked out the window. I saw that everything around: the ground, trees, roofs of houses, became white. It was the first snow. I thought: “Why is snow white?” And I decided to investigate this problem.
This problem allowed us to formulate the research topic: “Why is snow white?”
Having decided on the topic, I set a goal: to study and conduct experiments to answer the question “Why is snow white?”
To achieve this goal, the following tasks need to be solved:
1. Study literature that talks about snow.
2. Prove experimentally “Why is snow white?”
3. Summarize the knowledge gained.
Object of study: snow.
Subject of study: snow composition
Hypothesis: Let's assume that the white color of snow is due to the reflection of light.
Research methods:
1. Studying literature on the topic
2. Observation of the research object
3. Conducting experiments
4. Analysis of the results and conclusions from the study
Chapter I. Theoretical justification of experimental work.
1.1 What is snow?
What is snow? That's a lot, a lot of beautiful snowflakes; they fall and fall from a height onto the ground, onto trees, onto the roofs of houses - clean, fragile, sparkling. And then it fell - this amazing snow. He lay down with “magnificent carpets” and covered the ground with a white shroud. The fallen snow filled up all the holes and ditches, leveled the hillocks - completely transformed the plain. The forest has changed even more. The snow scattered in white clumps along the branches of the trees, covered the leaves and twigs that had fallen to the ground with a white blanket, and settled in high snowdrifts in the bushes. He revealed to an attentive eye many secrets of forest life - everything that happened was imprinted on the snow cover, leaving traces in the snow.
I found the meaning of the word “snow” in “Modern explanatory dictionary" Snow is hard precipitation, consisting of small ice crystals falling from clouds at temperatures below 0C. Snow forms when water vapor in the atmosphere freezes. Tiny crystals appear first. Following air currents, they move in all directions. Gradually, the crystals “stick” to each other until there are a hundred or more of them. When the size of the frozen ice floes turns out to be large enough, they begin to sink to the ground. We call these accumulations of ice floes snowflakes.
1.2 Where do snowflakes come from?
A snowflake is a frozen water crystal shaped like a six-pointed polyhedron.
Water vapor rises high above the ground. It is very cold at the top, and ice crystals form from it. They are very small. These are not snowflakes yet. As they fall down, the crystals quickly increase in size. This happens because there is a lot of water vapor in the air, which settles on their surface and freezes. This is how a crystalline piece of ice becomes a beautiful, delicate snowflake.
There are so many snowflakes and they are all different - not one is the same.
The largest snowflake ever recorded had a diameter of 12 cm. Typically, snowflakes are about 5 mm in diameter and weigh 0.004 g.
The crystals that make up snowflakes have a certain shape. This is either a six-pointed star or a thin plate shaped like a hexagon. The fact is that the main water crystal has the shape of a regular hexagon in the plane.
In 1885, American farmer Wilson Bentley took the first successful photograph of a snowflake under a microscope. He did this for 46 years and took more than 5,000 unique photographs. Based on his work, it was proven that no two snowflakes are alike.
At different temperatures crystals of various shapes are formed
The most beautiful snowflakes fall where the climate is harsher - for example, in the north.
Depending on the weather conditions“Their own” snow falls in different places.
For the formation of large flakes of snowflakes, complete calmness is necessary; the longer the snowflakes travel, the more they collide and adhere to each other.
At low temperatures and strong wind snowflakes collide in the air, crumble and fall to the ground in the form of fragments - “diamond dust”.
1.3 Classification of snowflakes.
Prisms- there are both 6-gonal plates and thin columns with a 6-gonal cross-section. Prisms are tiny in size and almost invisible to the naked eye. The edges of the prism are often decorated with various complex patterns.
Needles- thin and long snow crystals, they form at a temperature of about -5 degrees.
When examined, they look like small light hairs.
Dendrites- or tree-like, have pronounced branching thin rays. Most often these are large crystals and can be seen with the naked eye. Maximum size The dendrite can reach 30 cm in diameter.
12-pointed snowflakes- sometimes columns with tips are formed with the plates rotated relative to each other by 30 degrees. When rays grow from each plate, a crystal with 12 rays is obtained.
Hollow posts- cavities sometimes form inside columns with a hexagonal cross-section. Interestingly, the shape of the cavities is symmetrical relative to the center of the crystal. Necessary high magnification to see half of the small snowflakes.
Fern-like dendrites- this type is one of the largest. The branches of star-shaped dendrites grow thin and very frequent, as a result the snowflake begins to look like a fern.
Irregularly shaped crystals- snow crystals are often small, asymmetrical and fused with each other. To get beautiful symmetrical crystals, you need a successful combination of many weather circumstances.
Triangular crystals- such snowflakes are formed at a temperature of about -2 degrees. In fact, these are hexagonal prisms, some of the sides of which are much shorter than others. But rays can grow on the edges of these.
Bullet sockets- sometimes when crystals form, they can grow together and grow in random directions. Such formations easily break into individual crystals, similar to bullets. Hence the unusual name.
1.4 Why is snow white?
When a Russian person is asked to imagine winter, the first thing he sees in his imagination is snow, a snow-white cover that shrouds everything around. We are so accustomed to the color of snow that we don’t even think about why there is snow. white. It turns out that all the colors we perceive depend on sun rays. Black objects completely absorb sunlight, which is why we perceive them as black. And if an object completely reflects a ray of sun, then the color will appear white to us.
Snow is frozen water, and as we know, ice is colorless. Why is snow white? From the Internet and the children's encyclopedia “Everything about Everything,” I learned that snowflakes are 95% air. The crystals of snowflakes are not smooth, but have edges. The reflection of light from the faces of these crystals makes the snow white. Ice remains colorless because it transmits the entire ray of sunlight through it. And every snowflake would transmit all the light through itself and would also have no color. But snowflakes usually fall on top of each other in random 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 the snow. Snow is formed from snowflakes, and snowflakes are formed from a huge number of crystals. These crystals are not smooth, but have edges. This is the answer to our question, why is snow white? It is from the edges that sunlight is reflected. Water in the atmosphere is steam, it freezes, and transparent crystals form. Due to the movement of air, the crystals move freely up and down. In this chaotic movement, the crystals connect with each other. And when, finally, too many crystals gather together, then they begin to fall to the ground in the form of snowflakes that are familiar to us. It turns out that the color of snow is white, because the light of the sun that it reflects is white. Think if a ray of sunshine 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 turn pinkish, so at this moment the snow appears pink to us.
Interesting Facts:
#1: Did you know that snow is not always white? In many regions of the world, people have seen it in red, green, blue and even black! The reason for this variety of colors is tiny bacteria, fungi, and dust contained in the air and absorbed by snowflakes as they fall to the earth's surface.
Conclusion on Chapter I
1. I learned that snow is solid precipitation consisting of small ice crystals.
2. Each snowflake is a collection of small pieces of ice.
3. Snow is formed from snowflakes, and snowflakes are formed from a huge number of crystals.
Chapter II. Organization of experimental work
on the problem “Why is snow white?”
From my observations while studying literature, I learned that any snowflake has the shape of a six-pointed star. Regardless of the shape of the snowflakes, they are all white. And the snow is white, white, and if the sun is shining, it becomes dazzling white. Why? A snowflake consists of crystals of ice and air; light falling on the rays of a snowflake is reflected from them, scattered and perceived by us as white. And when a ray of sunlight hits the crystals, it is reflected from it and blinds our eyes.
I decided to conduct experiments to prove that snow is really white.
2.1 Conducting experiments to answer the question “Why is snow white?”
How I conducted the experiments
Experience No. 1
I put snow on red cardboard and compared it with a white sheet of paper. Conclusion: Snow is white.
Experience No. 2
I took a transparent plastic bag. I cut it into small pieces. Each piece is a “snowflake”. I put all the pieces in a transparent glass. They were positioned differently.
Result: “snow” in a white glass.
Experience No. 3
I poured water into a glass and put it in the freezer. The water turned into transparent ice. Mom broke the ice into small pieces. He turned white.
Conclusion
Pieces plastic bag and the pieces of ice are individually transparent. Light passes through them and is not reflected. When the pieces of the package lie chaotically (in different ways, they reflect light in different directions.
Conclusion
Snow is white because each snowflake reflects light in different directions. In scientific language - “light is scattered.” This makes the snow white.
The question of why snow is white is familiar to every person since childhood. But not all children, and even adults, know the correct answer why small snowflakes are blue or green. Everyone knows that snow is frozen water, or rather ice. But since ice is transparent and capable of transmitting light through it, why are the snowdrifts that cover the ground far from being opaque, but having a very distinct color?
In past centuries, when there were no such advanced technologies that made it possible to study everything natural processes, scientists have wrestled with the question of why snow is white. However, the answer was never found. Only when the entire process of creating snow from the very beginning to the end became clear, some guesses about the “snow-white cover” appeared.
It all starts with the fact that under the influence of warm sunlight, water from rivers, lakes and seas turns into steam and rises high into the atmospheric layers, where permafrost. Steam, in turn, having the properties liquid water, due to the high subzero temperature, it begins to freeze and turns into ice crystals. These are snowflakes that are ready to fall to the ground over time. For the most part, in places where it is warm, pieces of ice fall in the form of wet precipitation, melting while still in the air.
How snow is formed is now clear, but why, when it falls to the ground, does it suddenly turn white?
The question is relevant, because snowflakes, while still in the air, have the same properties of transmitting light through themselves as ice. But one thing should not be forgotten: the edges of the lenses are located at chaotic angles, which randomly refracts sunlight, and they do not absorb it, but transmit it further. And when the snowflakes gather into a “snow-white blanket,” the rays of the sun, refracted from one snowflake to another, pass through the entire cover. Many rays are reflected into our eyes, which is why often when you look at the snow you have to squint. sunlight too bright to be perceived by unprotected eyes.
But it is not entirely correct to ask the question of why snow is white, because it is not always “clean”. People see him like this only when the rays of sunlight fall on him. For example, at sunset it may turn pinkish, and in the light of a yellow lantern it may be slightly grayish, just like in cloudy weather.
Changes in the color of the snow are also possible in the air layers, when the snowflakes are just beginning to “fall to the ground.” For example, various pollen from trees and flowers, dust from dry land rises and meets grains of snow in air currents. If such snow does not have time to melt and is preserved by a small cover, then its color will certainly have different shades. Under these conditions, asking why the snow is white is inappropriate.
However, snowflakes are not just pieces of ice flying chaotically downwards, which for unknown reasons decided to cover the ground with a “white blanket”.
The main properties of snow are to protect the earth from the cold by covering it with a thick blanket. Yes, yes, it would seem paradoxical to warm and preserve the crop and soil from freezing, but it is true. It has poor thermal conductivity, allowing it to contain heat escaping from the ground and create a “thermal cushion”. It’s not for nothing that igloos were built by residents of the far north. Ice, like snow, retains heat well, creating unique favorable conditions for life.
You should not lose sight of the fact that the size of snowflakes depends on the weather conditions outside the window. If it’s cold enough, the ice flakes are small, almost invisible. But if the sun is shining and the air is not so cold, then the size of a snowflake can reach several centimeters. So, in 1944, ten-centimeter “grains of ice” fell in Moscow.
When thinking about winter, one always imagines a snow-white blanket that envelops everything around, but rarely does anyone think 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 familiar with.
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 is equal to the angle of reflection. Billions of microcrystals, shaped like a regular hexagon, absorb the sun's 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.
The fact is that every snowflake consists of ice particles, i.e. lots of ice crystals. Each such crystal has edges (like gem). Sunlight reflects off the edges of the crystals, turning the snow white.
But you may ask, how do snowflakes form? Very simple. The water particles that rise upward in the form of steam freeze in the atmosphere, turning into clear and clear crystals. These crystals fly up and down, obeying the movement of air. Moving randomly in the atmosphere, the crystals collide with each other and form snowflakes.
Also, other small air particles (for example, dust or soil lifted from the ground by the wind) get into snowflakes. Gradually, the snowflakes become heavier and, under the force of gravity, fall to the ground in the form of snow. Each snowflake can contain from 2 to 200 crystals!
But the most interesting thing is the shape of the snow crystals. They always have the appearance of a six-pointed star or a hexagon shape (although sometimes crystals of other shapes are found). Moreover, each of the six faces is exactly similar to the others, like twin sisters. And despite the fact that the crystals that make up snowflakes are so similar to each other, it is almost impossible to find two identical snowflakes in nature. Each of them is unique and unique in its design and shape. Try to carefully examine a few snowflakes yourself, and you will see that this is absolutely true!
First. Snowflakes are 95% air. That is why they fall very slowly, at a speed of 0.9 km/hour.
Second. Why is snow white? Just because snow has air in its structure. In this case, all possible rays of light are simply reflected from the boundary of ice crystals with air and scattered.
Third. There have been cases in history when snow of a different color fell. For example, black snow fell in Switzerland in 1969, just in time for Christmas, and in 1955 green snow fell in California.
Fourth. In Antarctica and high mountains, snow of pink, purple, red and yellowish-brown colors is found. This is facilitated by creatures that live in the snow and are called chlamydomonas snow.
This is the smallest algae that accumulates the pigment astaxanthin. Pinkish or red snow can often be found in the Caucasus mountains.
If you lift upper layer, then the snow below will be white, ordinary.
Algae begin to change color, or rather bloom, when the temperature rises slightly. If the sun warms the surface of the snow, the algae, which were previously numb in the snow, come to life, begin an active life, and quickly accumulate pigments. If you melt the snow, then under a microscope you can see how quickly red particles rush around in the water - this is snow chlamydomonas.
Fifth. When a snowflake falls into the water, it emits a high-frequency sound that is not picked up by humans, but, according to scientists, fish really don’t like it.
Sixth. Snow in normal conditions melts at 0 degrees Celsius. However, a significant amount of snow can evaporate at sub-zero temperatures without being converted into a liquid phase. This process occurs when the sun's rays hit the snow.
Seventh. IN winter time every year, snow reflects up to 90% of the sun's rays from the Earth's surface, directing them back into space, thereby preventing the Earth from warming up.
Eighth. During a snowfall in 1987, a world record snowflake with a diameter of 38 cm was found in Fort Coy (Montana, USA).
Prepared by Inna BAKANOVA
When writing this article, materials from the book were used
Masaru Emoto "Messages from water, secret codes of ice crystals."
Secrets of the birth of snowflakes
How are snowflakes formed? Why do snowflakes always have the correct crystal structure? The following video will answer these questions.
I would like to draw your attention to the fact that snowflakes are formed in high layers of the atmosphere. There, high above the earth, purity and harmony reign, they are not influenced by negative human thoughts, therefore all snowflakes are beautiful and unique.
Have you ever wondered why snow is white? After all, when snow melts, it turns into water, and the water is clear. Why is snow white?
A little about color
Different things have different colors. Visible light from the Sun or any other light source consists of many wavelengths. Our eyes perceive different wavelengths as different colors.
Different objects have different colors because the individual particles (molecules and atoms) that make up the object have different vibrational frequencies.
When light interacts with an object, the wavelengths that the object reflects or absorbs determine what color our eyes perceive. When an object reflects all wavelengths of light from the Sun that are in the visible spectrum, the object appears white.
When we see a fire truck, it is red because the paint on it reflects certain wavelengths in the red region of the visible spectrum and absorbs other wavelengths.
If we look at the water, it is transparent. This means that wavelengths of light pass through it rather than being reflected back into your eyes.
If you look at an individual snowflake, it is also almost transparent. But when we see snow, that is, a large concentration of snowflakes, then all the light is reflected and does not pass through them. And we see snow in white.
The key factor here is the way light interacts with the mass of complex snowflakes and air that make up the snow. Snowflakes have a complex and various shapes. When light hits a snowflake (ice crystal), it meets a bend and hits another ice crystal, then another, and so on. The process continues until the light reflects off the snow rather than passing straight through it to the ground.
If there is dirt in the snow, then some of the waves will be absorbed, and we will see this dirt. But if the snow is fresh, then most of the light waves will eventually be reflected and we will see snow-white snow.
You may have noticed that sometimes snow can also have a bluish or blue tint. Snow is white when light is reflected by ice crystals only slightly a large number of times, without penetrating very deeply into the snow. If we look at a small pile of snow, it will appear white because almost all visible light is reflected.
The situation is different for light that is not reflected, but penetrates into the snow. When this light penetrates the snow, the ice crystals scatter a large amount of light. The deeper the light penetrates, the more scattering occurs.
We see light from the upper layers (up to about 1 cm), while in the lower layers the light is scattered and absorbed. For light that penetrates deeper, the longer wavelengths that exist at the red end of the light spectrum are absorbed, leaving shorter wavelengths on the blue end of the spectrum that are reflected back for us to see.
It can be said that blue light travels most easily through ice. It is important to understand here that spectral selection is associated with absorption, and not with reflection, as is sometimes thought.
In this case, we can talk about snow as a filter that allows or does not allow different colors to pass through. If we have a centimeter layer of snow, then all the light passes through it. If it is a meter or more, then only blue light will pass through it (scatter into it). An analogy can be made with a cup of coffee. When we first pour it, it is light; the more of it, the darker it becomes.
