Why is the sky blue from the point of view. Why is the sky blue and the sunset red? Description, photo and video. The phenomenon of blue sky in terms of physics

Why is the sky blue - it is very difficult to find the answer to such a simple question. Many scientists have puzzled over the answer. The best solution to the problem was proposed about 100 years ago by the English physicist Lord John Rayleigh.

But let's start from the beginning. The sun emits a dazzlingly pure white light. So the color of the sky should be the same, but it is still blue. What happens to white light in the earth's atmosphere?

Sunburst color

The true color of sunlight is white. White light is a mixture of colored rays. With a prism, we can make a rainbow. The prism decomposes the white beam into colored bands: red, orange, yellow, green, blue, indigo and violet. Combining together, these rays again form white light. It can be assumed, that sunlight first split into colored components. Then something happens, and only blue rays reach the surface of the Earth.

Hypotheses put forward at different times

There are several possible explanations. The air surrounding the Earth is a mixture of gases: nitrogen, oxygen, argon and others. The atmosphere also contains water vapor and ice crystals. Dust and other small particles are suspended in the air. IN upper layers atmosphere contains a layer of ozone. Could this be the reason?

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Some scientists believed that ozone and water molecules absorb red rays and transmit blue ones. But it turned out that there was simply not enough ozone and water in the atmosphere to color the sky blue.

In 1869, Englishman John Tyndall suggested that dust and other particles scatter light. Blue light is the least scattered and passes through layers of such particles to reach the Earth's surface. In his laboratory, he created a model of smog and illuminated it with a bright white beam. The smog turned deep blue.

Tyndall decided that if the air were absolutely pure, then nothing would scatter the light, and we could admire the bright white sky. Lord Rayleigh also supported this idea, but not for long. In 1899, he published his explanation: it is air, not dust or smoke, that turns the sky blue.

Relationship between color and wavelength

Part of the sun's rays pass between the gas molecules without colliding with them and reach the Earth's surface unchanged. The other, most part, is absorbed by gas molecules. When photons are absorbed, the molecules are excited, that is, they are charged with energy, and then emit it in the form of again photons. These secondary photons have different wavelengths and can be any color from red to purple.

They scatter in all directions: to the Earth, and to the Sun, and to the sides. Lord Rayleigh suggested that the color of the emitted beam depends on the predominance of quanta of one color or another in the beam. When a gas molecule collides with solar photons, there are eight blue quanta for one secondary red quantum.

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Air mass movement and condensation

What is the result? Intense blue light literally pours down on us from all directions from billions of atmospheric gas molecules. This light has photons of other colors mixed in, so it doesn't have a pure blue hue.

Why is the sky blue?

Before reaching the surface of the earth, where people can contemplate it, sunlight must pass through the entire air shell of the planet. The light has wide range, in which the primary colors, shades of the rainbow, still stand out. Of this spectrum, red has the longest wavelength of light, while violet has the shortest. At sunset, the solar disk rapidly turns red and rushes closer to the horizon.

In this case, the light has to overcome an increasing thickness of air, and part of the waves is lost. Purple disappears first, then blue, blue. The longest waves of red color continue to penetrate to the surface of the Earth to the last, and therefore the solar disk and the halo around it until the last moments have reddish hues.

Why the sky is blue - interesting video

What changes in the evening?

Closer to sunset, the Sun rushes to the horizon, the lower it falls, the faster the evening approaches. At such times, the layer of atmosphere that separates the original sunlight from earth's surface, begins to increase sharply due to the angle of inclination. At some point, the thickening layer ceases to transmit other light waves except red, and at that moment the sky is painted in this color. Blue is no longer present, it is absorbed in the process of passing through the layers of the atmosphere.

Interesting fact: at sunset, the sun and sky pass through a whole gamut of hues as one or the other of them ceases to pass through the atmosphere. The same can be observed at the time of sunrise, the causes of both phenomena are the same.

What happens at sunrise?

At sunrise Sun rays go through the same process, but in reverse order. That is, first, the first rays break through the thickness of the atmosphere at a strong angle, only the red spectrum reaches the surface. Therefore, the sunrise initially dawns red. Then, as the sunrise and the angle change, waves of other colors begin to pass - the sky turns orange, and then it becomes habitually blue. A half-day deep blue of the sky is observed, and then, by evening, it begins to turn again to crimson. On one side of the sky, far from the sun, there is a blue-black tint, but the closer to the setting star, the more red shades can be seen near the horizon, until the Sun disappears completely.

Sunlight is white, that is, it includes all the colors of the spectrum. It would seem that the sky should also be white, but it is blue.

Surely your child knows the phrase "Every Hunter Wants to Know Where the Pheasant Sits", which helps to remember the colors of the rainbow. And the rainbow The best way understand how light breaks down into waves of different frequencies. The longest wavelength is for red, the shortest for violet and blue.

The air, which contains gas molecules, ice microcrystals and water drops, scatters light with a shorter wavelength more strongly, therefore blue and purple there is eight times more red in the sky. This effect is called Rayleigh scattering.

Draw an analogy with balls rolling down a corrugated board. The larger the ball, the less likely it is to veer off course or get stuck.

Explain why the sky cannot be other colors

Why isn't the sky purple?

It is logical to assume that the sky should be purple, because this color has the shortest wavelength. But here the features of sunlight and the structure of the human eye come into play. The spectrum of sunlight is uneven, there are fewer shades of violet in it than other colors. And part of the spectrum is not visible to the human eye, which further reduces the percentage of shades of purple in the sky.

Why isn't the sky green?

A child may ask, "Since scattering increases with decreasing wavelength, why isn't the sky green?" Not only blue rays are scattered in the atmosphere. Their wave is the shortest, so they are the most noticeable and brightest. But if the human eye were arranged differently, the sky would seem green to us. After all, the wavelength of this color is slightly longer than that of blue.

Light is arranged differently than paint. If you mix green, blue and purple paints, you get a dark color. With light, the opposite is true: the more colors are mixed, the lighter the result is.

Tell me about the sunset

We see blue skies when the Sun shines from above. When it approaches the horizon, and the angle of incidence of the sun's rays decreases, the rays go tangentially, passing a much larger path. Because of this, waves of the blue-blue spectrum are absorbed in the atmosphere and do not reach the Earth. In the atmosphere, red and yellow colors. Therefore, at sunset the sky turns red.

On a clear sunny day, the sky above us has a bright blue color. In the evening, at sunset, the sky takes on a deep red color with numerous shades that is pleasing to the eye. So why is the sky blue during the day? What makes a sunset red? How transparent air shimmers with blue and red hues in different time days?

I will present 2 answers here: the first one is more simplified for the general reader, the second one is more scientific and accurate. Choose for yourself which one you like.

1. Why is the sky blue and not green? Answer for dummies

Light from the sun or a lamp looks white, but white is actually a mixture of all 7 existing colors: red, orange, yellow, green, cyan, indigo, and violet (Figure 1). The sky (atmosphere) is filled with air. Air is a mixture of tiny gas molecules and small pieces of solid material such as dust. As sunlight travels through air, it collides with air particles. When a beam of light hits gas molecules, it can "bounce" in the other direction (scatter).

Some component colors of white light, such as red and orange, pass directly from the Sun into our eyes without scattering. But most blue rays "bounce" off air particles in all directions. Thus, the whole sky is literally pierced with blue rays. When you look up, some of this blue light reaches your eye and you see blue light from all over your head! Here, in fact, why the sky is blue!

Naturally, everything is simplified to the maximum, but below is a paragraph where the property of our beloved sky above our heads is more fundamentally described and the reasons that explain why the color of the sky is blue and not green after all!

2. Why is the sky blue? advanced answer

Let's take a closer look at the nature of light and color. Color, as everyone knows, is a property of light that our eyes and brain can perceive and define. Light from the sun is a large amount of white rays, which consist of all 7 colors of the rainbow. Light has the property of dispersion (Fig. 1). Everything is illuminated by the Sun, but some objects reflect rays of only one color, for example, blue, while other objects only reflect rays of yellow, etc. This is how a person defines colors. So, the Sun shines on the Earth with its white rays, but the atmosphere (a thick layer of air) envelops it, and when this white (consisting of all colors) ray passes through the atmosphere, it is the air that scatters (spreads) all 7 colored rays of the white sun ray, but with greater force, it is its blue-blue rays (in other words, the atmosphere literally begins to glow blue). Other colors directly fall from the Sun into our eyes (Fig. 2).

Why is blue the color most diffused in the atmosphere? This a natural phenomenon, and it is described by the Rayleigh physical law. To put it more simply, there is a formula that Rayleigh deduced in 1871, and which determines how the scattering of light (a beam) depends on the color of this beam (that is, on such a property of the beam as its wavelength). And it just so happened that the sky-blue color has the shortest wavelength and, accordingly, the greatest scattering.

Why is the sky red during sunrise and sunset? At sunset or sunrise, the sun is low on the horizon, which causes the sun's rays to fall obliquely

yut to Earth. The beam length, of course, increases many times (Fig. 3), and therefore, at such a huge distance, almost the entire short-wavelength (blue-blue) part of the spectrum is scattered in the atmosphere and does not reach the Earth's surface. Only long waves, yellow-red, reach us. This is exactly the color the sky takes on during sunrise and sunset. That is why the sky, in addition to blue and blue, is also yellow and red!

And now, for a complete understanding of all of the above, a few words about what the atmosphere is like.

What is the atmosphere (vault of heaven)?

The atmosphere is a mixture of gas molecules and other materials that surround the Earth. Basically, the atmosphere consists of nitrogen gases (78%) and oxygen (21%). Gases and water (in the form of vapours, droplets and ice crystals) are the most common constituents of the atmosphere. There are also small amounts of other gases, as well as many fine particulate matter such as dust, soot, ash, salt from the oceans, etc. The composition of the atmosphere changes with geographical location, the weather and much more. Somewhere there may be more water in the air after a rainstorm or near the ocean, somewhere volcanoes erupt large amounts of dust particles high into the atmosphere.

The atmosphere is denser in its lower part, near the Earth. It gradually thins out with height. There is no sharp gap between atmosphere and space. That is why we see overflows of blue and blue in the sky, precisely because the atmosphere in the sky is different everywhere, has a different structure and properties.

“Mom, why is the sky blue and not red or yellow?” Many parents are confused by this phrase. It turns out that we, adults who introduce our baby to the outside world, do not ourselves know the answer to such a “ complex issue» ? and simply, not knowing what to answer to our baby, we translate the topic, or, in order to compose an explanation accessible to the child, we have to rack our brains. Therefore, let's figure it out with you why the sky is blue and how to explain it to a small child in a simple way.

Light, consisting of seven spectral colors, passes through the atmosphere. Solar photons collide with gas molecules in the air, causing them to scatter. And the most interesting thing is that after that, the number of particles emitting a short wave of blue becomes eight times more than others. It turns out that before our eyes, sunlight on the way to Earth turns from white to blue.

How to explain all this to a child? It is still too early to talk about solar photons colliding with gas molecules. We offer several versions of the answer to this difficult question.

• Sunlight is made up of 7 colors combined together: red, orange, yellow, green, blue, indigo and violet. (Look at the pictures with the spectrum, remember the rainbow.) Each ray passes through a thick layer of air high above us, as if through a sieve. All colors at this moment are splashed and it is blue that becomes the most visible, because it is the most persistent.
• The air looks transparent, but it actually has a bluish tint. The sun is very far away. When we look up at the sky, we see a very thick layer of air, so thick that we see that it is blue. You can take transparent cellophane, fold it many times and see how it has changed color and transparency. And then draw an analogy.
• The air around us consists of tiny and constantly moving particles (gases, dust and specks, water vapor). So small that they can only be seen with the help of special devices - microscopes. And sunlight combines 7 colors. A beam passing through the air collides with tiny particles and its constituent shades are separated. And since blue-blue prevails in the color scheme, we see it. Here it is necessary to show the child the spectrum.
• And you can do it quite simply - the sun paints the air blue.

If the child is very small and it is too early to talk about the spectra? , then you can just come up with something? (options from the forums)

kitty Well, for example, like this: there is such a magician in the world who has a brush with beautiful blue paints, he wakes up, and so that the children are light and joyful, he takes out blue paint and paints the sky with it, the paint is also magical - it does not spill and immediately dries ? , but when he is upset, the sky is not blue, but dark blue and the paint does not dry, but it's raining, and the wizard has a fairy sister, and when she sees that the children are tired, she paints the sky in a dark color and throws stars so that it is not very dark, and then the children have colorful dreams?

Vladimir Gor There are many seas and oceans on earth (show on the map) and in sunny weather the water is reflected in the sky and the sky becomes as blue as the water in the oceans and seas, just like it happens in the mirror (show something blue in the mirror) . This will be enough for the child to satisfy his curiosity.

Chena A fairy flew, she had paints in her basket, a bottle of blue paint fell and the paint spilled, so the sky is blue. In general, it all depends on the age of the baby ...

It is very important to involve your child in the discussion. Sometimes invite your why child to first think about the answer to the question. Try to hint, push him to conclusions. And then discuss and summarize the information. The baby needs your attention, recognition of his interests and respect for the first attempts to know the world. In this way, you will help develop your child's open and inquisitive personality.

We also read: how to explain to a child where babies come from

The sun, which heats and illuminates our Earth, thanks to which the world is painted with different colors, radiates pure white light. But when we look at the sky, we see blue and blue colors. Why not white, since the color of the sun's rays was originally like this, but the air is transparent?

Why do we see blue skies?

White is made up of the seven colors of the rainbow. That is, white is a mixture of red, orange, yellow, green, blue, blue, purple. The Earth's atmosphere is made up of a mixture of gases. The sun's rays, reaching the Earth, meet with gas molecules. Here the rays are reflected and decomposed into seven colors of the spectrum. The rays of the red spectrum (this includes: red, orange, yellow) are longer, they, for the most part, pass directly to the earth, without lingering in the atmosphere. The rays of the blue spectrum (green, cyan, indigo, violet) are short-wavelength. They bounce off air molecules in different sides(scatter) and fill the upper atmosphere. Therefore, the entire sky is permeated with blue light, spreading in different directions.

It is worth clarifying why we do not see the sky green, but we see it blue. This happens because the colors of the blue spectrum mix with each other and the result is a blue sky. In addition, the human eye perceives blue color better than, for example, violet. Then another interesting point is why the sky is blue and the sunset is red. The fact is that during the day the sun's rays are directed perpendicular to the surface of the Earth, and during sunset and sunrise - at an angle. With this position of the rays relative to the Earth, they have to move in the atmosphere over long distances, so the short spectrum waves go to the sides and become invisible, and the long spectrum waves are partially scattered across the sky. Therefore, we see the sunset and sunrise in red-orange tones.

How to explain to a child why the sky is blue?

Now that we have figured out the color of the sky ourselves, let's think about how to make an explanation of the question why the sky is blue accessible to children. For example, you can do this: the sun's rays, reaching the Earth's atmosphere, meet with air molecules. Here the solar beam is decomposed into colored light waves. As a result, red, orange, yellow light continues to move towards the Earth, and the colors of the blue spectrum are retained in the upper layers of the atmosphere and distributed over the sky, coloring it blue.

Knowing your children and their level of knowledge about our planet, you will be able to understand for yourself how easier it is to explain to your child why the sky is blue.

Astronomy for kids> Answers to FAQ >why is the sky blue

Let's talk about Why the sky is blue in a language accessible to children. This information will be useful to children and their parents.

When children look at the sky, they see an endless blue. Many even spend all day on the grass watching the clouds. It's time explain to children Why is the sky still blue?

To give complete explanation for children, parents should consider the reasons that may lead to such a phenomenon. But it can be difficult. At school you have heard about the existence of an atmosphere. It is a mixture of molecules (various gases) surrounding the planet. Depending on the location of your country and city, there may be more water in the atmosphere (near the ocean) or dust (if there is a volcano or desert nearby).

Further for the little ones necessary explain concept of light waves. Light is energy transmitted in waves. Each type defines its own wave, oscillating in magnetic and energy fields. Light is divided into very many types, which can have a longer (or shorter) length. Children must remember that light is included in a large group - " electromagnetic fields". The visible (which we observe with our own eyes) is part of it. It consists of a whole stream of colors, namely the entire spectrum of the rainbow: red, orange, yellow, green, blue, indigo and violet.

Light travels in a straight line, which is called the "speed of light." He travels until he encounters an obstacle in the form of a speck of dust or a drop of water. Then everything depends on the size of the wavelength and the object. Dust and water are longer than the wavelength, so the light bounces off - "reflection". It spreads in different directions, but remains white because it continues to contain the entire rainbow spectrum. But gas molecules are smaller. Therefore, it is necessary explain to children that this collision leads to different results.

In this case, the light is not reflected but absorbed by the molecule. Then it fills up and begins to radiate part of the color. Although now it still contains the entire spectrum, it highlights a specific one. High frequency (blue) is absorbed faster than low frequency (red). This scientific process was discovered and described in the 1870s by the English physicist Lord John Rayleigh. That is why the phenomenon was called "Rayleigh scattering".

This is the reason why we admire the blue sky. When light travels through the air, the red or yellow part is not involved. But blue is absorbed and reflected. This is especially noticeable when looking at the horizon from a distance. The blue color then appears lighter.

There are millions of questions that, being children, we do not receive an answer, and when we grow up, we are simply embarrassed to ask. One of these

And everything would be fine, and you can live without this knowledge, but when a child begins to ask such tricky questions to their parents - they often become ashamed, and they begin to change the subject. Then the child grows up not knowing the answer, he has his own children and everything repeats again. Let's break this "vicious circle" and understand the reasons why the sky is blue. Consider the issue from all possible points of view.

The phenomenon of blue sky in terms of physics

Let's get straight to the point, the sky is blue because the earth's atmosphere scatters the light of the sun. All research conducted over the past 200-300 years comes down to this. Consider a few axioms that affect the phenomenon blue sky:

1. The white light of the sun is a combination of different color streams. White color "separately" does not exist. As everyone knows, there are only 7 colors (red, orange, yellow, green, blue, blue, purple), the rest of the colors are obtained only when they are combined. White color is obtained by combining all seven colors. It is worth considering that it is precisely the colors that we can distinguish with the eye that are meant.
2. The atmosphere is not empty, it consists of many gases: nitrogen (78%), oxygen (21%), carbon dioxide, water in its various states (steam, ice crystals). There is also a lot of dust around us, elements of various metals. All of them distort the white light of the sun.
3. The air that surrounds us and that we breathe is actually opaque. In any case, in large quantities. We do not live in a vacuum, after all.

From these three facts we will proceed further.

Story

Back in the 19th century, a scientist named John Tyndall conducted research that proved that we see the sky blue because of particles in the atmosphere. In his laboratory, he artificially created a fog with dust particles and directed a bright white beam at it - the color of the fog changed to bluish. 30 years later, in 1899, the physicist Rayleigh refuted the research of his predecessor and published evidence that the sky is blue because of air molecules and no dust in it. This phenomenon is called “diffuse sky radiation”; you can read more about this in Wikipedia.

Why is the sky blue?

What is light? Light is a stream of photons, some we can see with our eyes and some we can't. So, for example, we see the standard spectrum of colors, but the ultraviolet, which also emits the sun, does not. What color we see in the end depends on the "wavelength" of this stream. This wavelength determines what color you get.

So. We have determined that the sun sends us quanta with a wavelength that corresponds to white, but how does it turn into blue as it passes through the atmosphere? Let's take the example of a rainbow. Rainbow - is a direct example of the refraction of light and its division into a spectrum. You can create your own rainbow using a glass prism at home. The decomposition of color into a spectrum is called dispersion.

So, our sky functions as a prism. Most white light changes its wavelength as it passes through gas molecules in the atmosphere. As a result, photons “leaving” the molecules have a different color. This color can be either purple, red, or blue and blue.

Why do we see blue and not red?

What color we eventually see when light travels from the sun to the earth depends on which photons prevail. For example, when light passes through the atmosphere, the number of blue color quanta is 8 times more than red, and violet is 16 times! This is due to the very different wavelength, so violet and blue scatter strongly, and red and yellow scatter much worse. Based on this theory, the sky should be purple, but it is not. This is due to the fact that purple is much worse perceived by the human eye, unlike blue. That is why the sky is blue.

Video about why the sky is blue:

Why is the sky blue during the day and the sunset is red

Everything, again, is connected with the dispersion of color. The angle of incidence of solar white light becomes smaller, and the light passes through more air molecules, the wavelength of light increases. This amount is enough to diffuse to red.

Answer question for children

If a child asked you a question about the blue sky, you certainly will not tell him about dispersion, spectra and photons. It is enough to quote from the children's book "100 Children's Why" Tatiana Yatsenko:

Usually we draw the sun's rays in yellow. But in fact, the light of the sun is white and consists of seven colors. These are the colors of the rainbow: red, orange, yellow, green, blue, indigo, violet. Not all colors pass through the air, only blue, indigo and violet. They color the sky.

It would be enough. On our website you can also download a presentation on the topic: “Why the sky is blue” at the link: prezentaciya-pochemu-nebo-goluboe It may come in handy in the classroom at school.

We welcome the most inquisitive on the pages of our site! Today we will touch on a question that often worries inquisitive minds (especially children's), but not everyone finds an opportunity to figure out why is the sky blue because the air is actually transparent. Let's try to answer it briefly.

What does Wikipedia say?

If we don’t know something, then we can always find the answer in Wikipedia. So let's take a look there and see what this resource tells us.

As a matter of fact, here is a link to the relevant material.

Well said on Wikipedia! True, somehow it is not very clear. The only thing that can be sorted out is the fact that the sun's rays reach our atmosphere, something happens to them, and we see a blue sky. No, this will not work, let's try to understand in more detail and in a more understandable language why the sky is blue.

In fact, the reason for everything is such a thing as " light scattering»!

Light scattering

So, the Sun emits rays that are white. White, as you know, includes all the colors of the spectrum visible to us. Evidence of that - rainbow. It arises for the reason that sunlight, falling into water droplets, is refracted and breaks up into different colors. We also observe blue skies for a similar reason.

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The fact is that there are many gas molecules in the air, which scatter sunlight. Light particles scatter in different directions, so the blue color of the sky is visible to both earthlings and astronauts from the ISS in the form of a blue halo. But why is it blue, because there are at least seven colors in the spectrum, as they say: "Every hunter wants to know where the pheasant is sitting!".

Interesting fact! A person inhales about 20 kg of air per day. We get this volume by taking 22,000 breaths a day.

Why is the sky blue?

Each color has its own wavelength. In the following figure, you can see how this indicator varies.

Violet diffuses too much, and the colors from green to red, on the contrary, do not scatter very intensively. So it turns out, blue and blue particles are the golden mean. Violet, despite the fact that it scatters better than blue, we do not notice because of our perception: with the same brightness, blue is perceived by our eyes much better than its counterpart.

Here is a good video on this topic, which helped us to understand this issue.