Why is the water transparent and the snow white. Summaries of the lesson "Snow, ice and their properties
About why the snow is white, and not black, blue, red or some other, each of us has thought at least once in our lives. Most often, the question “why is snow white” is asked by children to parents, but not even all adults know the answer to this question.
To understand why snow is of such a color, you first need to determine the concept of color in general. What is color in terms of physics?
We are surrounded by electromagnetic radiation, which is also called electromagnetic waves.. These waves are everywhere, but most of these waves are invisible to the human eye.
The visible part of electromagnetic radiation is perceived as color. From the point of view of science, any color is a wave of electromagnetic radiation, which is perceived by human vision and is converted into a color sensation.
The primary source of electromagnetic radiation for us is the sun. The sun's rays, that is, waves, contain the entire spectrum of visible radiation, that is, all basic seven colors - red, orange, yellow, green, blue, blue, violet.
Merging, the colors of the visible spectrum form a white color.
Some items completely absorb light waves - we see them black, other subjects let in the sunthat is, are transparent. It is glass, water or ice.
Have you read fairy tales about living and dead water? Then you will be interested to know what is really with their help and much, much more!
Do you know what the density of sea water is and why it is easier to swim in it than in river? Very interesting information is found, learn something new for yourself!
Most of the objects in our world absorb part of the rays, and some reflect. For example, you can take a regular leaf from a green tree.
That green leaf tells us that from the visible spectrum of solar radiation it reflects the rays of green light, and all absorbs the rest.
Orange orange absorbs all rays except orange, red poppy - everything except red, and so on.
The following can be said about snow - it reflects all the rays of the visible spectrum, so we see it white, that is, what the light from the Sun is for us.
Why is snow white and not transparent? ^
And a little more science. Someone will ask why the snow is still white, and not transparent. After all, snow is essentially water, only in a different aggregate state.
Water is a liquid, ice is a solid, snow is a friable substance consisting of individual ice crystals. Water and ice are transparent.
But in fairness it should be noted that in nature there are no absolutely transparent bodies, as there are no absolutely black and absolutely white bodies. Even glass is not completely transparent.
Be that as it may, water or ice has a more or less smooth surface, which affects the passage of sunlight through them.
Passing through the thickness of smooth ice, the rays are not absorbed and practically do not refract, most of them are transmitted, and a smaller part is reflected from the surface.
Snow is very different in its properties from ice, it is loose and not at all smooth.
To learn more about the properties of snow, just consider the snowflake. Each snowflake is unique and has its own pattern.
But the common feature of all snowflakes is that they are not smooth, but consist of many faces, that is, the smallest surfaces located at an angle to each other.
The mass of snow consists of many such snowflakes that are attached to each other. Falling on a snowy surface, sunlight is repeatedly refracted and reflected from the faces of snowflakes.
In the end, most of the visible solar radiation is reflected from the snow. Moreover, as already mentioned, the rays of the entire visible spectrum are reflected, so we see snow white.
Snow can be compared to crushed glass or diamonds. If you imagine a huge scattering of diamonds, then it will also seem to us white, sparkling.
Perhaps everyone noticed that in bright sunlight in winter, the surface of the snow sparkles and shimmers with all the colors of the rainbow.
So, this incident sunlight refracts and decays into individual spectral colors. Therefore, we see multi-colored sparkles on white snow.
Do you know what equals and why it differs from fresh boiling point?
What is the dew point, how important is it, and how can it be calculated, read, keep comfort in your home!
When the snow melts, a special kind of water is formed - melt. How can I get it at home, how healthy is it and how is it used, read here:
, it is very interesting!
When thinking about winter, a snow-white cover is always imagined, which has enveloped everything around, and rarely does anyone think about why it is white.
Water droplets in the atmosphere at freezing temperatures freeze and turn into ice, falling to the ground in the form of snow. Ice is solid water; 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 will notice that they look like crystals that resemble in their shape a regular hexagon with faces. During a snowfall, it is the faces of snowflakes that reflect light rays that give the snow the usual white color for us.
On earth, snow cover is a cluster of snowflakes located very densely 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 white. The source of light rays at night are the moon, stars, lights.
However, the reason for the “whiteness” of the snow cover lies not only in the ability of the faces of the ice crystals to reflect the light incident on them, but also on the cleanliness of their surface. The bottom line is that not a single snowflake can be perfectly transparent. In the atmosphere, water droplets mix with different particles (dust, industrial emissions and other pollutants) that are capable of absorbing non-reflected light rays.
Why does snow glisten?
In this case, the well-known law applies: the angle of incidence is equal to the angle of reflection. Billions of microcrystals in the shape of a regular hexagon absorb the sun's rays, refract them, and then reflect in different directions and at different angles, like "sun bunnies". Therefore, we see how snowflakes sparkle and shimmer in the sun.
Why do snowflakes crunch and creak underfoot?
Walking in the snow, you can often hear a crunch or creak underfoot. This sound is obtained because the crystals of snowflakes under mechanical pressure rub together and break. However, this phenomenon can not be observed always, but only at a certain air temperature.
The fact is that snow creaks only at a temperature of 2 to 20 degrees below zero, and in different temperature ranges, creaking and crunching are accompanied by a special sound. This is due to the fact that in severe frost the crystals of snowflakes become denser and stronger, and at a temperature of 0 ° C and higher 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. While trillions of snowflakes break, the sound becomes much stronger and a person clearly hears the characteristic crackling of snow.
Olga Chertova
Summaries of the lesson "Snow, ice and their properties"
On the mug classes"Young ecologist" we are with children senior group continue to experiment. This time experimentally we study properties of snow and ice.
TARGET: To form an idea of snowice and them properties.
Introduce children to physical properties of snow and ice.
TASKS:
Educational. Help children understand why when temperature changes snow and ice change their properties.
Consolidate knowledge about properties of snow and ice.
To teach children to analyze, draw conclusions in the process of experimentation.
Developing. To develop thinking, the ability to express one’s thoughts in a consistent manner, and interest in winter natural phenomena.
Educational. To bring joy from the discoveries obtained as a result of experiments.
Preliminary work: Monitoring in the snow, viewing of snowflakes, characteristics snow: dry (wet, loose (dense, cold, deep, sparkling, crumbly, games with in the snow, experiments, reading the story “First snow ”E. Drone.
Materials and equipment: disposable plates for snow(on each table on a deep and flat plate, snow, magnifying glasses by the number of children, by half a cut apple on a napkin, a disposable spoon, three containers of water, circles of different colors, illustrative models of snowflakes and ice floes with a designation properties of snow and ice, napkins and towel.
Guys, what time of year does this riddle:
Snow in the fields,
Ice on the rivers
Blizzard walks -
When does this happen? (In winter)
And the following riddles speak of phenomena inanimate nature winters. Guess them.
He's fluffy, silvery,
But do not touch his hand,
Become a drop of clean
How to catch in the palm of your hand. (snow)
Transparent like glass
But you can’t insert it in the window. (Ice)
Asterisk circled
In the air a little bit
Sat and melted
On my palm. (Snowflake)
The teacher draws the attention of children to artificial snowflakes. Are they real? When and where can you see real snowflakes?
Listen to how interesting the writer is about snowflakes.
V. Arkhangelsky. (Children read about how snowflakes form).
What happens snow? It turns out snow can be different. On very frosty days, it is crispy and crumbles. But if it gets a little warmer on the street and there comes a light, small frost, then the snow will become sticky, and then we can fashion a snow woman, build a snow fortress, and play snowballs.
And when it happens snow and ice(Answers).
Time snow and ice is only in winter, then they probably are somewhat similar to each other. What do you think? (Answers). Today we will conduct experiments and find out what are similar to each other snow and ice and how they differ.
Experience is practical actions with objects for recognizing them. properties.
I dialed yesterday snow and ice and laid it out in plates, but I wonder what happened to him? I suggest going to the snow laboratory, but the entrance to it is not easy (passing through the arc, the children answer the question "Where does the snowflake live?")
Now we are research scientists, we will find out what they are snow and ice and what are their properties. And our assistant will be a special device for research. Find it on your tables, what is this device called? (magnifier). And what is a magnifying glass? (magnifying glass).
Guys, what happened to in the snow? (melted away) Why?
Means snow and ice forms from water under the influence of frost and melts in heat.
(a snowflake with the image 1 is attached to the board properties, a drop is drawn on a snowflake water: the snow is melting warm).
Let's take a closer look at the melted snow. What do you see? (dirty water). Guys, I saw some kids eating snow. Are they doing the right thing? Which one then snow to the touch? (cold). Can i eat snow? (no, snow cold and can be dirty).
Experience No. 1. "Color Definition".
Compare: what color is water, snow and ice(snow white, water and ice are colorless) And what else is white? (fastens 2 snowflake: snow white - in the center of a cotton snowflake, ice is colorless).
What colour snow? (white)
What color is the ice? (colorless)
Experience No. 2. “Definition of transparency”.
Let's do an experiment. Geometric shapes are under your plates, name them (circles). What color are they? Put one circle on an empty plate, at the top we will put snow, lower the other into the water, put the third circle under the ice. Where is the circle visible and where not? Why? (3 attached to the board snowflake: snow opaque - closed eye is drawn, transparent ice is open eye).
Experience No. 3. "Definition of smell".
Guys, how do you know snow and ice smell? (need to sniff). We smell the apple first, which apple? (fragrant, fragrant). And now snow(at no smell of snow) (fastens 4 snowflake: snow and the ice is odorless - a nose is painted on a snowflake).
Let's try to stick in snow stickwhat happened? Is it possible to stick a stick in the ice? It can be concluded that loose snowand the ice is hard.
Take a handful snow and pour it. What can you call it snow property? (Loose). What about ice? I AM "accidentally" dropped the ice, what happened to him? (he split, he is fragile).
Physical fitness:
Snow fluffy everything flies, (raise their hands up and slowly lower)
A blizzard howls.
how many snow covered, (show snowdrifts)
All paths skidded!
We rake the tracks (imitate actions)
And let's go play snowballs. (walking)
Snow is white todaywhite (raise their hands up and down)
It is light around him.
We’ll put on gloves (put on mittens)
and we put on gloves (put on each finger)
Every finger we wear
Will you fur coat us warm.
Well done! You have shown me so many experiments, but now I want to show you, sit down more conveniently. See: I have three jars. Pour water into one (a child is invited to check the temperature of the water, (cold). In the second we pour it warm, but how do we get warm water, what water should be poured at first: hot or cold, why? (cold, then hot). In the third jar I will pour hot. In three jars I will lower snow at the same time. Where snow melted faster, and where is slower? (the warmer the water, the faster it melts snowmelting speed snow depends on water temperature).
Guys, and now let's remember which snow and ice properties? (at the end of each experiment, snowflakes with properties of snow and ice) Children’s attention is drawn to the fact that snow and ice is frozen water.
Let’s Now Combine Everything We Learned About snow and ice.
Snow - White, opaque, friable, loose, under the influence of heat turns into water.
And ice is colorless, transparent, hard, brittle, turns into water under the influence of heat.
And now that you and I met snow properties, let’s try to cut out the snowflakes ourselves and see how we get them. (Kids carve snowflakes).
Summarizing lessons: How much we learned today about snowIt's time to go back. Did you like our occupation? What is the most memorable thing?
Have you ever wondered - why is snow white? After all, when the snow melts, it turns into water, and the water is clear. Why is snow white?
Little bit about color
Different things have different colors. Visible light from the sun or from any other light source consists of many wavelengths. Our eyes perceive different wavelengths in the form of different colors.
Different objects have different colors, because the individual particles (molecules and atoms) that make up the object have different vibration 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 the wavelengths of light from the Sun, which are in the visible spectrum, the object looks white.
When we see a fire truck, it is red because the paint with which it is painted reflects certain wavelengths in the red region of the visible spectrum and absorbs other wavelengths.
If we look at the water, then it is transparent. This means that the wavelengths of light pass through it, and do not bounce back into your eyes.
If you look at a separate snowflake, then it is also almost transparent. But when we see snow, that is, a large concentration of snowflakes, then all the light is reflected, but does not pass through them. And we see snow in white.
The key factor here is the way that light interacts with the mass of complex-shaped snowflakes and the air that make up the snow. Snowflakes have a complex and diverse shape. When light hits a snowflake (ice crystal), it encounters a bend and falls on another ice crystal, then on another, and so on. The process continues until light is reflected from the snow, and does not pass directly through it to the ground.
If there is dirt in the snow, then part 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 ultimately be reflected and we will see snow-white snow.
You may have noticed that sometimes snow can also have a bluish or blue tint. The snow is white, when light is reflected by ice crystals only a small number of times, without penetrating very deep into the snow. If we look at a small pile of snow, it will be white, because almost all visible light is reflected.
Another situation is for light that does not reflect, but penetrates the snow. When this light enters the snow, ice crystals scatter a large amount of light. The deeper the light penetrates, the more scatter 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, longer waves that exist at the red end of the light spectrum are absorbed, leaving shorter wavelengths on the blue side of the spectrum that are reflected back and we see them.
It can be said that blue light most easily passes 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 passes or does not pass different colors. 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 (scattered in it). You can draw an analogy with a cup of coffee. When we just pour it, it is light, the more it is, the darker it becomes.
Snow makes winter white, it seems to hide the darkness and dirt of autumn, so it brings so much joy. Children especially love him. For them, snow is one of the main winter funs. From it, children make fortresses and snowmen, skiing and sledding on it, or without a visible goal, just flounders in it for hours. It is no wonder that the moment comes when the kids begin to wonder with their parents why the snow is white.
The nature of light and its role
To answer this question in an exhaustive and accessible way, adults must have some knowledge of light, color perception, and snow. But you need to start with visible light. Everything around is riddled with electromagnetic waves, but people are only able to see their meager fraction. The visible part of the spectrum consists of waves ranging in length from 550 to 630 nanometers.
Everything that is 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 heats the skin and can even burn it if you are on a sunny beach for a long time.
Vision - priceless gift of naturethanks to which people have the opportunity to create a stable picture of being and to know the world. However, without light, human vision turns into a useless tool. It is easy to show the child by going into a room where there are no windows, for example, in a bathroom. While the light is on, objects around are visible, their colors are distinguishable. But as soon as the light goes out, the room plunges into impenetrable darkness, all things and colors cease to exist for sight, until they are again lit by the sun, a living fire or a light bulb.