Why does the sky seem blue. What color is the sky? Why is the sky blue in terms of physics? Scientists find blue skies on Pluto and traces of lakes on Mars

Sunlight is white, meaning it includes all the colors in 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 is the best way to understand how light breaks down into waves of different frequencies. The longest wavelength is for red, the shortest is for violet and blue.

The air, which contains gas molecules, micro-crystals of ice and water droplets, scatters light with a short wavelength more strongly, so there are eight times more blue and purple in the sky than red. 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 stray 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, with fewer shades of violet than other colors. And the human eye does not see part of the spectrum, which further reduces the percentage of shades of violet in the sky.

Why isn't the sky green?

A child may have a question: "Since the scattering increases with decreasing wavelength, why is the sky not green?" Not only blue rays are scattered in the atmosphere. Their wave is the shortest, so they are the most visible and brightest. But if the human eye was 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 not like paint. If you mix green, blue and purple colors, you get a dark color. With light, the opposite is true: the more colors are mixed, the lighter the result is.

Tell us 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 are scattered. Therefore, at sunset, the sky turns red.

In short, ... "Sunlight, interacting with air molecules, is scattered into different colors. Of all the colors, blue is the best prone to scattering. It turns out that he actually captures airspace. "

Now let's take a closer look

Only children can ask such simple questions that a completely adult person does not know how to answer. The most common question tormenting children's heads: "Why is the sky blue?" However, not every parent knows the correct answer even for himself. The science of physics and scientists who have been trying to answer it for more than one hundred years will help to find it.

Erroneous explanations

People have been looking for an answer to this question for centuries. Ancient people believed that this color is the favorite for Zeus and Jupiter. At one time, the explanation of the color of the sky worried such great minds as Leonardo da Vinci and Newton. Leonardo da Vinci believed that when combined with each other, darkness and light form a lighter shade - blue. Newton associated the blue color with the accumulation of a large number of water droplets in the sky. However, it was only in the 19th century that it was possible to come to the correct conclusion.

Range

In order for a child to understand the correct explanation using the science of physics, he first needs to understand that a ray of light is particles flying at high speed - segments of an electromagnetic wave. In a stream of light, long and short beams move together, and are perceived by the human eye together as white light. Penetrating into the atmosphere through the smallest drops of water and dust, they scatter to all colors of the spectrum (rainbows).

John William Rayleigh

Back in 1871, the British physicist Lord Rayleigh noticed the dependence of the intensity of the scattered light on the wavelength. The scattering of the sun's light by irregularities in the atmosphere explains why the sky is blue. According to Rayleigh's law, blue sun rays are scattered much more intensely than orange and red, since they have a shorter wavelength.

The air near the Earth's surface and high in the sky is composed of molecules, which scatters sunlight still high in the air atmosphere. It reaches the observer from all directions, even the most distant ones. The diffused light spectrum differs markedly from direct sunlight. The energy of the former has been moved to the yellow-green part, and the energy of the latter to the blue.

The more direct sunlight is scattered, the colder the color will appear. The strongest dispersion, i.e. the shortest wave is in the violet color, the long-wave scattering in the red. Therefore, during the setting of the Sun, the distant territories of the sky appear blue, and the closest ones appear pink or scarlet.

Sunrises and sunsets

During dusk and dawn, a person most often sees pink and orange hues in the sky. This is because light from the Sun travels very low to the surface of the earth. Because of this, the path that the light needs to travel during dusk and dawn is much longer than during the day. Because the rays travel the longest path through the atmosphere, most of the blue light is scattered, so the light from the sun and nearby clouds appear reddish or pink to a person.

White sunlight consists of seven colors of the rainbow and comes to us in waves. The air scatters these waves. It scatters long waves worst of all, and short waves best of all. The blue light wave is short, so we see the sky in blue.

Detailed answer from the point of view of physics

The sun's rays go to our planet through a thick layer of the atmosphere, which itself is transparent, but not at all empty: it consists of 78% nitrogen and 21% oxygen, and also includes steam, water droplets, tiny ice crystals and solid particles earth dust and sea salt, soot and ash. Breaking through the inhomogeneous layers of the atmosphere, the rays of the sun scatter - diffraction occurs, that is, the splitting of light into components.

White light consists of seven colors of the spectrum - red, orange, yellow, green, cyan, blue and violet - and spreads in waves. Each of the colors has a different wavelength.

Blue, blue, violet colors are from the short-wave part of the spectrum, therefore they are very strongly scattered in the atmosphere. The mixture of these colors appears to our eye as blue. At sunrise and sunset, the sun's rays become longer and go to the earth at a sharper angle - and we observe how the blue completely dissipates for a while: it is replaced by red and yellow tones from the long-wave part of the spectrum.

The overflows of blue color, which can sometimes be observed in the sky, are explained by the inhomogeneity of the composition of the atmosphere - passing through it, even blue light waves are not scattered in the same way.

The physical law of light scattering is called Rayleigh's law in honor of the English physicist who discovered it and says that the intensity of the scattered light is inversely proportional to the fourth power of the wavelength of light. The formula looks like this: I ~ 1 / λ4

For a designer and programmer: the color of the blue sky

Interestingly, for each designer and programmer, the color of the blue sky will be denoted differently - depending on personal perception, because blue is the collective name for a whole group of light shades of blue - and sometimes even with a subtle shift towards green. Each of these shades has its own color coordinates.

The closest hue to spectral blue is the 130 hue in the Windows color system, denoted 00BFFF.

Interestingly, in the CMYK system, cyan can be called one of the main system colors - cyan, although there is a shade of green in it. In Russian, cyan is best matched by the definition of "sea green". But the sea is often called blue.

The song "There is a golden city under the blue sky"

The most famous song, which was performed by Boris Grebenshchikov and his group "Aquarium" called "City", does not belong to either BG or the group. Yes, and was called in the original "Paradise". The author of the text - the poet-emigrant Anri Volokhonsky - composed these poems in 1972, having heard a string melody performed by V. Vavilov on the disc. On the envelope of the disc, the melody was shamelessly attributed to Francesco da Milano, who does not have such a piece. The traces of the author of the original melody are now lost, and different performers have interpreted it in different ways.

And we hear Volokhonsky's text in Grebenshchikov's version. As everyone knows, BG sings: "Under the blue sky ..." In the original - "Above". The poet was inspired by the book of the prophet Ezekiel, and the city above the sky was, of course, the heavenly Jerusalem, “I had not yet seen the earthly,” Volokhonsky said.

Aquarium - "Under the blue sky"

We are all accustomed to the fact that the color of the sky is a fickle characteristic. Fog, clouds, time of day - everything affects the color of the dome over your head. Its daily change does not occupy the minds of most adults, which cannot be said about children. They are constantly wondering why the sky is blue in terms of physics, or what colors the sunset red. Let's try to understand these not the easiest questions.

Changeable

It is worth starting with an answer to the question of what, in fact, the sky is. In the ancient world, it was really seen as a dome covering the Earth. Today, however, hardly anyone does not know that, no matter how high the curious explorer ascends, he will not be able to reach this dome. The sky is not a thing, but rather a panorama that opens when viewed from the surface of the planet, a kind of appearance woven of light. Moreover, if you observe from different points, it may look different. So, from the one that has risen above the clouds, a completely different view opens than from the ground at this time.

The clear sky is blue, but as soon as the clouds come in, it turns gray, leaden, or off-white. The night sky is black, sometimes you can see reddish areas on it. This is a reflection of the city's artificial lighting. The reason for all such changes is light and its interaction with air and particles of various substances in it.

The nature of color

In order to answer the question of why the sky is blue from the point of view of physics, you need to remember what color is. This is a wave of a certain length. The light coming from the Sun to the Earth is seen as white. Even from Newton's experiments, it is known that it is a bundle of seven rays: red, orange, yellow, green, light blue, blue and violet. Colors differ in wavelength. The red-orange spectrum includes the most impressive waves in this parameter. parts of the spectrum are characterized by a short wavelength. The decomposition of light into a spectrum occurs when it collides with molecules of various substances, while part of the waves can be absorbed, and part of it can be scattered.

Investigating the cause

Many scientists have tried to explain why the sky is blue in terms of physics. All researchers sought to find a phenomenon or process that scatters light in the planet's atmosphere in such a way that as a result, only blue reaches us. Water was also the first candidate for the role of such particles. It was believed that they absorb red light and transmit blue, and as a result, we see the blue sky. Subsequent calculations, however, showed that the amount of ozone, ice crystals and water vapor molecules in the atmosphere was not enough to give the sky a blue color.

The reason is pollution

At the next stage of research, John Tyndall suggested that dust plays the role of the desired particles. Blue light has the greatest resistance to scattering, and therefore is able to pass through all layers of dust and other suspended particles. Tyndall conducted an experiment that confirmed his assumption. He created a model of a smog in a laboratory and illuminated it with bright white light. The smog took on a blue hue. The scientist made an unambiguous conclusion from his research: the color of the sky is determined by dust particles, that is, if the air of the Earth was clean, then not blue, but white skies shone above the heads of people.

Lord's research

The final point on the question of why the sky is blue (from the point of view of physics) was put by the English scientist, Lord D. Rayleigh. He proved that it is not dust or smog that colors the space overhead in the shade we are accustomed to. It's about the air itself. Gas molecules absorb the largest and primarily the longest wavelengths equivalent to red. In this case, the blue is scattered. This is how the color of the sky we see in clear weather is explained today.

The attentive will notice that, following the logic of scientists, the dome over your head should be purple, since it is this color that has the shortest wavelength in the visible range. However, this is not a mistake: the proportion of violet in the spectrum is much less than that of blue, and human eyes are more sensitive to the latter. In fact, the blue we see is the result of mixing blue with purple and some other colors.

Sunsets and clouds

Everyone knows that at different times of the day you can see different colors of the sky. Photos of beautiful sunsets over the sea or lake are a great illustration of this. All sorts of shades of red and yellow combined with blue and dark blue make such a spectacle unforgettable. And it is explained by the same scattering of light. The fact is that during dusk and dawn, the sun's rays have to overcome a much larger path through the atmosphere than during the height of the day. In this case, the light of the blue-green part of the spectrum is scattered in different directions and the clouds located at the horizon line become colored in shades of red.

When the sky is covered with clouds, the picture changes completely. unable to overcome the dense layer, and most of them simply do not reach the ground. The rays that managed to pass through the clouds meet with water drops of rain and clouds, which again distort the light. As a result of all these transformations, white light reaches the earth, if the clouds are small in size, and gray, when the sky is covered by impressive clouds, which again absorb part of the rays.

Other heaven

Interestingly, on other planets of the solar system, when viewed from the surface, you can see the sky, which is very different from that of the earth. On space objects, deprived of the atmosphere, the sun's rays freely reach the surface. As a result, the sky here is black, without any shade. Such a picture can be seen on the Moon, Mercury and Pluto.

The Martian sky has a reddish-orange hue. The reason for this lies in the dust with which the atmosphere of the planet is saturated. It is painted in different shades of red and orange. When the Sun rises above the horizon, the Martian sky turns pinkish-red, while the portion of it immediately surrounding the luminary's disk appears blue or even purple.

The sky above Saturn is the same color as on Earth. Aquamarine skies stretch over Uranus. The reason lies in the methane haze located in the upper planets.

Venus is hidden from the eyes of researchers by a dense layer of clouds. It does not allow the rays of the blue-green spectrum to reach the planet's surface, so the sky here is yellow-orange with a gray stripe along the horizon.

Exploring overhead space during the day reveals no less wonders than exploring the starry sky. Understanding the processes taking place in and behind the clouds helps to comprehend the reason for things that are quite familiar to the average person, which, nevertheless, not everyone can explain on the fly.

"Dad, mom, why is the sky blue?" - how many times parents and the older generation shy away from hearing such a question from a small child.

It seems that people with higher education know almost everything, but this interest of children is often perplexing. Perhaps a physicist can easily find an explanation that satisfies the kid.

However, the "average" parents do not know what to say to their child. You need to figure out which explanation is suitable for children, and which one is suitable for an adult.

To understand the blueness of the sky, you need to remember the school physics course. Colors are distinguished by their ability to scatter (due to wavelength) in the gas envelope surrounding the Earth. So, the red color has a low ability, therefore it is used, for example, as external side lighting of aircraft.

Thus, those colors that have an increased ability to scatter in the air are actively used to mask any objects from air and ground opponents. These are usually the blue and violet parts of the spectrum.

Consider scattering using the example of a sunset. Since the red color has a low scattering power, the departure of the sun is accompanied by crimson, scarlet flashes and other shades of red. What is the reason for this? Let's consider in order.

We argue further. The blue and blue "separation" of the spectrum is between green and violet colors. All these shades are distinguished by their high scattering power. And the maximum scattering of a certain shade in a particular environment paints it in this color.

Now we need to explain the following fact: if the purple tint is better diffused in the air, why is the sky blue, and, for example, not purple. This phenomenon is explained by the fact that the human organs of vision, with equal brightness, "prefer" just blue shades, and not violet or green.

Who is painting the sky?

How can you answer a child who looks at the parent with enthusiasm and expects an understandable and quite clear answer? A parent's departure from the question can offend the baby or disbelieve him of the "omnipotence" of mom or dad. What are the possible explanations?

Answer # 1. As in the mirror

It is extremely difficult for a child of 2-3 years old to tell about spectra, wavelengths and other physical wisdom. But there is no need to dismiss it, it is better to give the maximum simple explanation, satisfying the natural curiosity inherent in a tiny child.

There are many reservoirs on our Earth: there are rivers, lakes, and seas (we show the map to the child). When it's sunny outside, the water is reflected, like in a mirror, in the heavens. This is why the sky is as blue as the water in the lake. You can show your child a blue object in the mirror.

For young children, this explanation is sufficient.

Answer No. 2. Splashes in the sieve

An older child can be given a more realistic explanation. Tell him that the sunbeam has seven shades: red, orange, yellow, green, blue, blue, and purple. At this point, show a drawing of a rainbow.

All rays penetrate to the Earth through a dense layer of air, as if through a magic sieve. Each ray begins to splatter into its constituent parts, but the blue color remains, since it is the most persistent.

Answer number 3. The sky is cellophane

The air close to us seems transparent, like a thin plastic bag, but its real color is blue. This is especially noticeable when you look at the heavens. Invite the child to lift their head and explain that since the air layer is very dense, it takes on a bluish tint.

For greater effect, take a plastic bag and fold it several times, inviting the child to see how it changed color and transparency.

Answer number 4. Air is small particles

For preschool children, the following explanation is suitable: air masses are a "mixture" of various mobile particles (gas, dust, litter, water vapor). They are so small that they can be seen by people with special equipment - microscopes.

The sun's rays include seven shades. Passing through air masses, the beam collides with small particles, as a result of which all colors disintegrate. Since the blue hue is the most persistent, we can distinguish it in the sky.

Answer number 5. Short beams

The sun warms us with its rays, and they seem to us yellow, like in children's drawings. However, each ray actually resembles a bright rainbow. But the air around us includes many particles invisible to the eye.

When a heavenly body sends rays to Earth, not all of them reach their destination. Part of the rays (which is blue) is very short and does not have time to hit the Earth, therefore it dissolves in the air and becomes lighter. Heaven is the same air, only very high.

That is why when the child lifts his head, he sees the sun's rays dissolved in the air above. That is why the sky turns blue.

It is very important for children to receive a quick explanation, but it is not always possible to remember or come up with a simple and understandable answer. Avoiding conversation is certainly not the best scenario, but it’s better to prepare.

Try to explain to your child what you are going to tell, but do it a little later. Be sure to indicate the exact time, otherwise the baby will think that you are deceiving him. You can do the following:

1. Think of the planetariums, in which experts very fascinatingly explain the history of the emergence of the Earth, talk about the starry sky. The kid will definitely like this fascinating story. And even if the guide does not explain where the blue sky came from, he will learn a lot of new and unusual things.
2. If it is not possible to go to the planetarium or the question remains unanswered, you will have time to search in any sources, for example, on the net. Just choose an explanation based on the age and level of intellectual development of the children. And do not forget to thank your child, because it is he who helps you develop.

Why the sky is blue? Such questions bother many kids for reasons who get to know the world around them. It's good if the parent himself knows where the blue over his head comes from. Our answer options will also help with this.

Before telling your version, invite your child to reflect and put forward his own idea.

In such a simple way, you can bring up an inquisitive baby who always seeks to find an explanation for every fact that excites him.

Hello, I am Nadezhda Plotnikova. Having successfully completed her studies at SUSU as a special psychologist, she devoted several years to working with children with developmental problems and consulting parents on raising babies. I use the experience gained, including in the creation of articles of a psychological orientation. Of course, in no way do I pretend to be the ultimate truth, but I hope that my articles will help dear readers to deal with any difficulties.