We all know that depending on celestial point, in which we observe the Sun, its color can vary greatly.

For example, at the zenith it is white, at sunset it is red, and sometimes even crimson. In fact, this is only an appearance - it is not the color of our luminary that changes, but its perception by the human eye. Why is this happening?

The solar spectrum is a combination of seven primary colors - remember the rainbow and the famous saying about the hunter and the pheasant, which determines the color sequence: red, yellow, green, and so on until purple.

But in an atmosphere filled with the most various types aerosol suspensions (water vapor, dust particles), each color scatters differently. For example, violet and blue are best scattered, and red is worse. This phenomenon is called dispersion of sunlight.

The reason is that color, in fact, is an electromagnetic wave of a certain length. Accordingly, different waves have different wavelengths. And the eye perceives them depending on the thickness atmospheric air separating it from the source of light, that is, the Sun.

Being at the zenith, it appears white, because the sun's rays fall on the Earth's surface at a right angle (naturally, that place on the surface where the observer is located is meant), and the thickness of the air that affects the refraction of light is relatively small. A white person seems to be a combination of all colors at once.

By the way, the sky appears blue also due to the dispersion of light: since blue, violet and blue colors, having the shortest wavelengths, scatter in the atmosphere much faster than the rest of the spectrum. That is, passing red, yellow and other rays with longer wavelengths, atmospheric particles of water and dust scatter blue rays in themselves, which give the sky its color.

The farther the Sun makes its usual daily path and descends to the horizon line, the greater the thickness of the atmospheric layer becomes, through which the sun's rays have to pass, and the more they scatter. The red color is the most resistant to scattering, as it has greatest length waves. Therefore, only he is perceived by the eyes of an observer who looks at the setting star. The remaining colors of the solar spectrum are completely scattered and absorbed by the aerosol suspension in the atmosphere.

As a result, there is a direct dependence of the scattering of spectral rays on the thickness of atmospheric air and the density of the suspension it contains. Vivid evidence of this can be observed with global emissions into the atmosphere of substances denser than air, for example, volcanic dust.

So, after 1883, when the famous eruption of the Krakatau volcano took place, for quite a long time in the most diverse places on the planet one could see red sunsets of extraordinary brightness.

From red to purple, which are the main colors of the spectrum. The color seen by the eye is explained by the wavelength of the light. Accordingly, red gives the longest light, and purple the shortest.

During sunset, a person can observe a disk rapidly approaching the horizon. Wherein sunlight passes through ever greater thickness. The longer the wavelength of light, the less it is subject to absorption by the atmospheric layer and aerosol suspensions present in it. To explain this phenomenon, you need to consider physical properties blue and red colors, the usual shades of the sky.

When the sun is at its zenith, the observer can tell that the sky is blue. This is due to differences in optical properties blue and red colors, namely the ability to scatter and absorb. Blue is more absorbent than red, but its scattering power is much higher (four times) than that of red. The ratio of wavelength to light intensity is a proven physical pattern called the Rayleigh blue sky law.

When the sun is high, the layer of atmosphere and suspension separating the sky from the observer's eyes is relatively small, the short wave of blue is not completely absorbed, and the high scattering power "muffles" other colors. This is why the sky looks blue during the day.

When the time comes for sunset, the sun begins to rapidly descend to the line of the true horizon, and the layer of the atmosphere increases sharply. After a certain time, the layer becomes so dense that the blue color is almost completely absorbed, and the red color, due to its high resistance to absorption, comes to the fore.

Thus, at sunset, the sky and the luminary itself is seen by the human eye in various shades of red, from orange to bright scarlet. It should be noted that at sunrise the same thing is observed and for the same reasons.

It's nice to look in a dazzling blue sky or enjoy a crimson sunset. Many people enjoy admiring the beauties of the world around them, but not everyone understands the nature of what they observe. In particular, they find it difficult to answer the question why the sky is blue and the sunset is red.

The sun emits pure white light. It seems that the sky should be white, but it is seen as bright blue. Why is this happening?

Scientists for several centuries could not explain the blue color of the sky. From a school course in physics, everything that is white light can be decomposed with the help of a prism into its constituent colors. There is even a simple phrase for them: "Every Hunter Wants to Know Where the Pheasant Sits." Initial words This phrase allows you to remember the order of the colors in: red, yellow, green, cyan, indigo, violet.

Scientists have suggested that the blue color of the sky is due to the fact that the blue component of the solar spectrum best reaches the Earth's surface, while other colors are absorbed by ozone or dust scattered in the atmosphere. The explanations were quite interesting, but they were not confirmed by experiments and calculations.

Attempts to explain the blue color of the sky did not stop, and in 1899 Lord Rayleigh put forward a theory that finally gave an answer to this question. It turned out that the blue color of the sky is caused by the properties of air molecules. A certain amount of rays coming from the Sun reach the Earth's surface without interference, but most of them are absorbed by air molecules. By absorbing photons, air molecules are charged (excited) and already emit photons themselves. But these photons have a different wavelength, and photons that give blue color predominate among them. That is why the sky looks blue: the more sunny the day is and the less cloudy, the more saturated this blue color of the sky becomes.

But if the sky is blue, why does it turn crimson at sunset? The reason for this is very simple. Red component the solar spectrum is much worse absorbed by air molecules than other colors. During the day, the sun's rays enter the Earth's atmosphere at an angle that directly depends on the latitude at which the observer is located. At the equator this angle will be close to a straight line, closer to the poles it will decrease. As the Sun moves, the layer of air that light rays need to pass through before reaching the observer's eye increases - after all, the Sun is no longer overhead, but tends to the horizon. A thick layer of air absorbs most of the rays of the solar spectrum, but the red rays reach the observer almost without loss. That is why the sunset looks red.

On April 26, 2012, strange greenish clouds appeared in the sky over Moscow. inexplicable phenomenon alarmed the residents of the capital and excited the Russian Internet. It was suggested that an accident occurred at one of the enterprises, which was accompanied by the release of hazardous substances into the atmosphere. chemical substances. Fortunately, the information has not been confirmed.

Instruction

Chief sanitary doctor Russian Federation Gennady Onishchenko said that according to official data, there were no accidents at chemical plants in the Moscow region and nearby regions. Meanwhile, in some areas of Moscow, people really felt worse. Allergy sufferers and asthmatics understood the reason for this abnormal phenomenon.

After a long winter in the first days of April, a sharp warming, which caused a rapid melting of the snow cover, the early blooming of leaves on trees and the flowering of several of their species at once: birch, alder,

One of distinguishing features man is curiosity. Probably everyone, as a child, looked at the sky and wondered: “why is the sky blue?”. As it turns out, the answers to such seemingly simple questions require some knowledge in the field of physics, and therefore not every parent will be able to correctly explain to the child the reason for this phenomenon.

Consider this issue from a scientific point of view.

Wavelength range electromagnetic radiation covers almost the entire spectrum of electromagnetic radiation, which includes radiation visible to humans. The image below shows the dependence of the intensity of solar radiation on the wavelength of this radiation.

Analyzing this image, one can note the fact that visible radiation is also represented by uneven intensity for radiation of different wavelengths. So a relatively small contribution to visible radiation makes the violet color, and the largest - blue and green colors.

Why the sky is blue?

First of all, we are led to this question by the fact that air is a colorless gas and should not emit blue light. It is obvious that the cause of such radiation is our star.

As you know, white light is actually a combination of radiation of all colors of the visible spectrum. Using a prism, you can explicitly decompose light into the entire range of colors. A similar effect occurs in the sky after rain and forms a rainbow. When the sunlight hits earth's atmosphere, it begins to dissipate, i.e. radiation changes its direction. However, the peculiarity of the composition of air is such that when light enters it, radiation with a short wavelength is scattered more than long-wave radiation. Thus, taking into account the spectrum shown earlier, it can be seen that red and orange light will practically not change its trajectory, passing through the air, while violet and blue radiation will noticeably change their direction. For this reason, a kind of "wandering" short-wave light appears in the air, which is constantly scattered in this medium. As a result of the described phenomenon, it seems that short-wave radiation of the visible spectrum (violet, blue, blue) is emitted at every point in the sky.

The well-known fact of the perception of radiation is that the human eye can catch, see, radiation only if it directly hits the eye. Then, looking at the sky, you will most likely see the shades of that visible radiation, the wavelength of which is the smallest, since it is it that scatters best in the air.

Why don't you see a distinctly red color when you look at the Sun? Firstly, a person is unlikely to be able to carefully examine the Sun, since intense radiation can damage the visual organ. Secondly, despite the existence of such a phenomenon as the scattering of light in the air, nevertheless, most of the light emitted by the Sun reaches the surface of the Earth without being scattered. Therefore, all the colors of the visible spectrum of radiation are combined, forming light with a more pronounced white color.

Let us return to the light scattered by the air, the color of which, as we have already determined, should have the smallest wavelength. Of the visible radiation, violet has the shortest wavelength, followed by blue, and blue has a slightly longer wavelength. Taking into account the uneven intensity of the solar radiation, it becomes clear that the contribution of the violet color is negligible. Therefore, the largest contribution to the radiation scattered by the air is blue, followed by blue.

Why is the sunset red?

In the case when the Sun hides behind the horizon, we can observe the same long-wave radiation of red-orange color. In this case, the light from the Sun must travel a noticeably greater distance in the Earth's atmosphere before reaching the observer's eyes. In the place where the radiation of the Sun begins to interact with the atmosphere, blue and blue colors are most pronounced. However, with distance, shortwave radiation loses its intensity, as it is significantly scattered along the way. While longwave radiation does an excellent job of overcoming such large distances. This is why the Sun is red at sunset.

As mentioned earlier, although long-wave radiation is weakly scattered in air, there is still scattering. Therefore, being on the horizon, the Sun emits light, from which only the radiation of red-orange hues reaches the observer, which has time to dissipate somewhat in the atmosphere, forming the previously mentioned "stray" light. The latter paints the sky in variegated shades of red and orange.

Why are clouds white?

Speaking of clouds, we know that they are made up of microscopic droplets of liquid that scatter visible light almost uniformly, regardless of the wavelength of the radiation. Then the scattered light, directed in all directions from the droplet, is scattered again on other droplets. In this case, the combination of radiation of all wavelengths is preserved, and the clouds "glow" (reflect) in white.

If the weather is cloudy, then solar radiation reaches the Earth's surface in an insignificant amount. In the case of large clouds, or a large number of them, some of the sunlight is absorbed, so the sky dims and takes on a gray color.

Everyone knows that depending on the celestial point in which we observe the Sun, its color can vary greatly. For example, at the zenith it is white, at sunset it is red, and sometimes even crimson. In fact, this is only an appearance - it is not the color of our luminary that changes, but its perception by the human eye. Why is this happening?


The solar spectrum is a combination of seven primary colors - remember the rainbow and the famous saying about the hunter and the pheasant, which determines the color sequence: red, yellow, green, and so on until purple. But in an atmosphere filled with various types of aerosol suspensions (water vapor, dust particles), each color scatters differently. For example, violet and blue are best scattered, and red is worse. This phenomenon is called dispersion of sunlight.

The reason is that color, in fact, is an electromagnetic wave of a certain length. Accordingly, different waves have different wavelengths. And the eye perceives them depending on the thickness of the atmospheric air that separates it from the source of light, that is, the Sun. Being at the zenith, it appears white, because the sun's rays fall on the Earth's surface at a right angle (naturally, that place on the surface where the observer is located is meant), and the thickness of the air that affects the refraction of light is relatively small. A white person seems to be a combination of all colors at once.


By the way, the sky appears blue also due to the dispersion of light: since blue, violet and blue colors, having the shortest wavelengths, scatter in the atmosphere much faster than the rest of the spectrum. That is, passing red, yellow and other rays with longer wavelengths, atmospheric particles of water and dust scatter blue rays in themselves, which give the sky its color.

The farther the Sun makes its usual daily path and descends to the horizon line, the greater the thickness of the atmospheric layer becomes, through which the sun's rays have to pass, and the more they scatter. Red is the most resistant to scattering because it has the longest wavelength. Therefore, only he is perceived through the eyes of an observer who looks at the setting star. The remaining colors of the solar spectrum are completely scattered and absorbed by the aerosol suspension in the atmosphere.

As a result, there is a direct dependence of the scattering of spectral rays on the thickness of atmospheric air and the density of the suspension it contains. Vivid evidence of this can be observed with global emissions into the atmosphere of substances denser than air, for example, volcanic dust. So, after 1883, when the famous eruption of the Krakatau volcano took place, for quite a long time in the most diverse places on the planet one could see red sunsets of extraordinary brightness.

On a clear sunny day, the sky above us looks bright blue. In the evening, the sunset colors the sky in reds, pinks and oranges. Why is the sky blue? What makes a sunset red?

To answer these questions, you need to know what light is and what the Earth's atmosphere consists of.

Atmosphere

The atmosphere is the mixture of gases and other particles that surround the earth. Basically, the atmosphere consists of gaseous nitrogen (78%) and oxygen (21%). Argon gas and water (in the form of steam, droplets and ice crystals) are the next most common in the atmosphere, their concentration does not exceed 0.93% and 0.001%, respectively. The Earth's atmosphere also contains small amounts of other gases, as well as the smallest particles of dust, soot, ash, pollen and salt that enter the atmosphere from the oceans.

The composition of the atmosphere varies within small limits depending on the place, the weather, etc. The concentration of water in the atmosphere increases during torrential storms, as well as near the ocean. Volcanoes are capable of throwing huge amounts of ash high into the atmosphere. Technogenic pollution can also add various gases or dust and soot to the usual composition of the atmosphere.

Atmospheric density at low altitude near the Earth's surface is the highest, with increasing altitude it gradually decreases. There is no clear-cut boundary between the atmosphere and space.

light waves

Light is a form of energy that is carried by waves. In addition to light, waves carry other types of energy, for example, a sound wave is an air vibration. A light wave is an oscillation of electric and magnetic fields, this range is called the electromagnetic spectrum.

Electromagnetic waves propagate through airless space at a speed of 299.792 km/s. The speed of propagation of these waves is called the speed of light.

The radiation energy depends on the wavelength and its frequency. The wavelength is the distance between the two nearest peaks (or troughs) of a wave. Wave frequency is the number of wave oscillations per second. The longer the wave, the lower its frequency, and the less energy it carries.

Visible light colors

Visible light is the part of the electromagnetic spectrum that our eyes can see. The light emitted by the Sun or an incandescent lamp may appear white, but is actually a mixture of different colors. You can see the different colors of the visible spectrum of light by decomposing it into its components using a prism. This spectrum can also be observed in the sky in the form of a rainbow, which occurs due to the refraction of the light of the Sun in water droplets, acting as one giant prism.

The colors of the spectrum are mixed, continuously moving one into another. At one end of the spectrum is red or orange. These colors fade into yellow, green, blue, indigo and violet. Colors have different wavelengths, different frequencies, and different energies.

Propagation of light in the air

Light travels through space in a straight line as long as there are no obstacles in its path. When a light wave enters the atmosphere, light continues to propagate in a straight line until dust or gas molecules get in its way. In this case, what happens to the light will depend on its wavelength and the size of the particles in its path.

Dust particles and water droplets are much larger than the wavelength visible light. Light is reflected in different directions when it collides with these large particles. Different colors of visible light are equally reflected by these particles. Reflected light appears white because it still contains the same colors it had before it was reflected.

Gas molecules are smaller than the wavelength of visible light. If light wave collides with them, the result of the collision may be different. When light collides with a molecule of any gas, some of it is absorbed. A little later, the molecule begins to emit light in various directions. The color of the emitted light is the same color that was absorbed. But colors of different wavelengths are absorbed differently. All colors can be absorbed, but higher frequencies (blue) are much more absorbed than lower frequencies (red). This process is called Rayleigh scattering, named after the British physicist John Rayleigh, who discovered this scattering phenomenon in the 1870s.

Why is the sky blue?

The sky is blue due to Rayleigh scattering. As light travels through the atmosphere, most of the long wavelengths of the optical spectrum pass through unchanged. Only a small part of the red, orange and yellow colors interact with the air.

However, many shorter wavelengths of light are absorbed by gas molecules. After absorption, the blue color is emitted in all directions. It is scattered all over the sky. Whichever way you look, some of this scattered blue light reaches the observer. Since blue light is visible everywhere overhead, the sky looks blue.

If you look towards the horizon, the sky will have a paler hue. This is a result of the fact that light travels a greater distance in the atmosphere to the observer. The scattered light is again scattered by the atmosphere, and less blue reaches the observer's eye. Therefore, the color of the sky near the horizon appears paler or even appears completely white.

Black sky and white sun

From Earth, the Sun appears yellow. If we were in space or on the Moon, the Sun would appear white to us. There is no atmosphere in space that scatters sunlight. On Earth, some of the short wavelengths of sunlight (blue and violet) are absorbed by scattering. The rest of the spectrum looks yellow.

Also, in space, the sky looks dark or black instead of blue. This is the result of the absence of an atmosphere, hence the light does not scatter in any way.

Why is the sunset red?

As the sun goes down, the sunlight has to travel a greater distance in the atmosphere to reach the observer, so more sunlight is reflected and scattered by the atmosphere. Since less direct light reaches the observer, the Sun appears less bright. The color of the Sun also appears to be different, ranging from orange to red. This is due to the fact that even more short-wavelength colors, blue and green, are scattered. Only the long-wavelength components of the optical spectrum remain, which reach the observer's eyes.

The sky around the setting sun can be painted in different colors. The sky is most beautiful when the air contains many small particles of dust or water. These particles reflect light in all directions. In this case, shorter light waves are scattered. The observer sees light rays of longer wavelengths, and so the sky appears red, pink, or orange.

More about the atmosphere

What is atmosphere?

The atmosphere is a mixture of gases and other substances that surround the Earth, in the form of a thin, mostly transparent shell. The atmosphere is held in place by the Earth's gravity. The main components of the atmosphere are nitrogen (78.09%), oxygen (20.95%), argon (0.93%) and carbon dioxide (0.03%). The atmosphere also contains small amounts of water (in different places its concentration ranges from 0% to 4%), solid particles, gases neon, helium, methane, hydrogen, krypton, ozone and xenon. The science that studies the atmosphere is called meteorology.

Life on Earth would not be possible without the presence of an atmosphere that supplies the oxygen we need to breathe. In addition, the atmosphere performs another important function - it equalizes the temperature throughout the planet. If there were no atmosphere, then in some places on the planet there could be sizzling heat, and in other places it would be extremely cold, the temperature range could range from -170 ° C at night to + 120 ° C during the day. The atmosphere also protects us from the harmful radiation of the Sun and space, absorbing and scattering it.

Of the total amount of solar energy reaching the Earth, approximately 30% is reflected by clouds and the earth's surface back into space. The atmosphere absorbs approximately 19% of the Sun's radiation, and only 51% is absorbed by the Earth's surface.

Air has weight, although we do not realize it, and do not feel the pressure of the air column. At sea level, this pressure is one atmosphere, or 760 mmHg (1013 millibars or 101.3 kPa). With increasing height Atmosphere pressure is rapidly declining. The pressure drops by a factor of 10 for every 16 km in altitude. This means that at a pressure of 1 atmosphere at sea level, at an altitude of 16 km, the pressure will be 0.1 atm, and at an altitude of 32 km - 0.01 atm.

The density of the atmosphere in its lowest layers is 1.2 kg/m 3 . Each cubic centimeter of air contains approximately 2.7 * 10 19 molecules. At ground level, each molecule travels at about 1,600 km/h, while colliding with other molecules at a rate of 5 billion times per second.

Air density also drops rapidly with altitude. At a height of 3 km, the air density decreases by 30%. People living near sea level experience temporary breathing problems when raised to this altitude. The highest altitude at which people permanently live is 4 km.

The structure of the atmosphere

The atmosphere consists of different layers, the division into these layers occurs according to their temperature, molecular composition and electrical properties. These layers do not have pronounced boundaries, they change seasonally, and in addition, their parameters change at different latitudes.

Separation of the atmosphere into layers depending on their molecular composition

Homosphere

• Lower 100 km including Troposphere, Stratosphere and Mesopause.
• Makes up 99% of the mass of the atmosphere.
• Molecules are not separated by molecular weight.
• The composition is quite homogeneous, with the exception of some small local anomalies. Homogeneity is maintained by constant mixing, turbulence and turbulent diffusion.
• Water is one of two components distributed unevenly. When water vapor rises, it cools and condenses, then returning to the earth in the form of precipitation - snow and rain. The stratosphere itself is very dry.
• Ozone is another molecule whose distribution is uneven. (Read about the ozone layer in the stratosphere below.)

heterosphere

• Extends above the homosphere, includes the Thermosphere and the Exosphere.
• The separation of the molecules of this layer is based on their molecular weights. Heavier molecules such as nitrogen and oxygen are concentrated at the bottom of the layer. The lighter ones, helium and hydrogen, dominate in the upper part of the heterosphere.

Separation of the atmosphere into layers depending on their electrical properties.

Neutral atmosphere

• Below 100 km.

Ionosphere

• Approximately above 100 km.
• Contains electrically charged particles (ions) produced by the absorption of ultraviolet light
• The degree of ionization changes with height.
• Different layers reflect long and short radio waves. This allows radio signals propagating in a straight line to bend around the spherical surface of the earth.
• Auroras occur in these atmospheric layers.
• Magnetosphere is the upper part of the ionosphere, extending to about 70,000 km, this height depends on the intensity solar wind. The magnetosphere protects us from the high-energy charged particles of the solar wind by keeping them in the Earth's magnetic field.

Separation of the atmosphere into layers depending on their temperatures

Top border height troposphere depends on seasons and latitude. It extends from earth's surface up to a height of about 16 km at the equator, and up to a height of 9 km at the North and South Poles.

• The prefix "tropo" means change. The change in the parameters of the troposphere occurs due to weather conditions - for example, due to the movement of atmospheric fronts.
• As the altitude increases, the temperature drops. Warm air rises, then cools and descends back to Earth. This process is called convection, it occurs as a result of the movement air masses. The winds in this layer blow mainly vertically.
• This layer contains more molecules than all the other layers combined.

Stratosphere- extends approximately from a height of 11 km to 50 km.

• It has a very thin layer of air.
• The prefix "strato" refers to layers or layering.
• The lower part of the Stratosphere is quite calm. Jet planes often fly in the lower Stratosphere in order to get around bad weather in the Troposphere.
• Strong winds known as high-altitude jet streams blow in the upper part of the Stratosphere. They blow horizontally at speeds up to 480 km/h.
• The stratosphere contains ozone layer", located at an altitude of approximately 12 to 50 km (depending on latitude). Although the concentration of ozone in this layer is only 8 ml / m 3, it very effectively absorbs the harmful ultraviolet rays of the sun, thereby protecting life on earth. The ozone molecule consists of three oxygen atoms The oxygen molecules we breathe contain two oxygen atoms.
• The stratosphere is very cold, its temperature is about -55°C at the bottom and increases with height. The increase in temperature is due to the absorption of ultraviolet rays by oxygen and ozone.

Mesosphere- extends to altitudes of about 100 km.

• As the altitude increases, the temperature rises rapidly.

Thermosphere- extends to altitudes of about 400 km.

• With increasing altitude, the temperature rises rapidly due to the absorption of very short wavelength ultraviolet radiation.
• Meteors, or "shooting stars", begin to burn up at altitudes of about 110-130 km above the Earth's surface.

Exosphere- extends for hundreds of kilometers beyond the Thermosphere, gradually passing into outer space.

• The air density here is so low that the use of the concept of temperature loses all meaning.
• Molecules often fly off into space when they collide with each other.

Why is the color of the sky blue?

Visible light is a form of energy that can travel through space. Light from the sun or an incandescent lamp appears white when in reality it is a mixture of all colors. The main colors that make up the white color are red, orange, yellow, green, blue, indigo and violet. These colors continuously change into one another, therefore, in addition to the primary colors, there is also a huge number of various shades. All these colors and shades can be observed in the sky in the form of a rainbow that occurs in areas of high humidity.

The air that fills the entire sky is a mixture of minute gas molecules and small solid particles such as dust.

As sunlight passes through the air, it bumps into molecules and dust. When light collides with gas molecules, the light can be reflected in various directions. Some colors, such as red and orange, reach the observer directly by passing directly through the air. But most of the blue light is re-reflected from air molecules in all directions. In this way, blue light is scattered throughout the sky and it appears blue.

When we look up, some of this blue light reaches our eyes from all over the sky. Since blue is visible everywhere overhead, the sky looks blue.

IN outer space there is no air. Since there are no obstacles from which light could be reflected, the light propagates directly. The rays of light do not scatter, and the "sky" looks dark and black.

Experiments with light

The first experiment - decomposition of light into a spectrum

For this experiment you will need:

• a small mirror, a piece of white paper or cardboard, water;
• a large shallow vessel such as a cuvette or bowl, or a plastic ice cream box;
• sunny weather and a window facing the sunny side.

How to conduct an experiment:

1. Fill a cuvette or bowl 2/3 full with water, and place it on the floor or table so that direct sunlight reaches the water. The presence of direct sunlight is essential for the correct conduct of the experiment.
2. Place a mirror under water so that the sun's rays fall on it. Hold a piece of paper over the mirror so that the rays of the sun reflected by the mirror fall on the paper, if necessary, adjust their relative position. Observe the color spectrum on paper.

What's happening: The water and the mirror act like a prism, splitting the light into its color spectrum. This happens because the rays of light passing from one medium (air) to another (water) change their speed and direction. This phenomenon is called refraction. Different colors are refracted differently, violet rays are more strongly decelerated and change their direction more strongly. Red rays slow down and change their direction to a lesser extent. The light is split into its component colors and we can see the spectrum.

The second experiment - modeling the sky in a glass jar

Materials needed for the experiment:

• a transparent tall glass or a transparent plastic or glass jar;
• water, milk, teaspoon, flashlight;
• a dark room;

Conducting an experiment:

1. Fill a glass or jar 2/3 full with water, approximately 300-400 ml.
2. Add 0.5 to one tablespoon of milk to the water, shake the mixture.
3. Taking a glass and a flashlight, go to a dark room.
4. Hold a flashlight over a glass of water and point the beam of light at the surface of the water, look at the glass from the side. In this case, the water will have a bluish tint. Now point the flashlight at the side of the glass, and look at the beam of light from the other side of the glass, so that the light passes through the water. This will give the water a reddish tint. Place a flashlight under the glass and point the beam of light upwards while looking at the water from above. In this case, the reddish tint near the water will look more saturated.

What happens in this experiment is that small particles of milk suspended in water scatter the light coming from a flashlight in the same way that particles and molecules in the air scatter sunlight. When the glass is illuminated from above, the water appears bluish due to the fact that the blue color is scattered in all directions. When you look directly at the light through the water, the flashlight appears red, as some of the blue rays have been removed due to light scattering.

The third experiment - mixing colors

You will need:

• pencil, scissors, white cardboard or a piece of drawing paper;
• colored pencils or felt-tip pens, a ruler;
• a mug or a large cup with a diameter at the top of 7-10 cm or a caliper.
• Paper cup.

How to conduct an experiment:

1. If you don't have a caliper, use a mug as a template to draw a circle on a piece of cardboard and cut out the circle. Using a ruler, divide the circle into 7 approximately equal sectors.
2. Color these seven sectors in the colors of the main spectrum - red, orange, yellow, green, blue, indigo and violet. Try to paint the disk as accurately and evenly as possible.
3. Make a hole in the middle of the disc and put the disc on the pencil.
4. Make a hole in the bottom of the paper cup, the diameter of the hole should be slightly larger than the diameter of the pencil. Turn the cup upside down and insert a pencil with a disc into it so that the pencil lead rests on the table, adjust the position of the disc on the pencil so that the disc does not touch the bottom of the cup and is above it at a height of 0.5..1.5 cm.
5. Quickly spin the pencil and look at the spinning disk, note its color. If necessary, adjust the disk and pencil so that they can rotate easily.

Explanation of the phenomenon seen: the colors that paint the sectors on the disk are the main constituent colors white light. When the disk spins fast enough, the colors seem to blend and the disk looks white. Try experimenting with other color combinations.