It would seem that at school every diligent and not so diligent student knows what colors the spectrum is divided into, what each color is. However, no matter how diligently a child studies, he will never be answered the main questions that have troubled his restless mind since early childhood: why is the sky blue and why is the sunset red?
If you dive a little into physics, you will find that the red spectrum has the worst scattering. That is why, in order for the lights of an object to be visible from afar, they are made red. And yet, why is the sunset red and not blue or green?
Let's try to think logically. When the sun is directly at the horizon, its rays have to overcome a much larger layer of atmosphere than when the sun is at its zenith. Due to its low scatterability, the red color passes through this layer of the atmosphere almost unhindered, and all other colors of the spectrum are scattered so strongly when passing through the thickness of the Earth’s airspace that they are actually not visible at all. This is why the sunset is red!
From this we can conclude that the sunset will be redder the greater the layer of atmosphere between the sun and our eye. Also, in order for the sunset to be more red, or even crimson, you just need to get dusty and pollute the air, then other colors besides red will scatter even more.
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On a clear, sunny day, the sky looks bright blue.
In the evening, at sunset, the sky turns red, pink and orange.
Why the sky is blue? What makes the sunset red?
To answer these questions, we must study light and the earth's atmosphere.
Atmosphere
The atmosphere is a mixture of gas molecules and other substances that surround the Earth. These are mainly nitrogen (78%) and oxygen (21%). Other common substances include argon and water (in the form of vapor, liquid, and ice crystals).Also, in small quantities, there are other gases and small solid particles: dust particles, soot, pollen and salt from the ocean.
The composition of the atmosphere changes depending on location, weather and other things.
For example, there may be more water in the air after a hurricane or near the ocean. Volcanoes can release large amounts of ash into the atmosphere. Pollution can add various gases and soot. The atmosphere is pressed tightly against the entire surface of the Earth. It gradually becomes thinner as you rise higher and higher. There is no clear boundary between the atmosphere and space.
Light waves
Light is a piece of energy that is emitted and travels in the form of waves. Many types of energy are represented by a wave. For example, sound is air vibrations. Light is vibrations of electric and magnetic fields. This is only a small part of a huge range of electromagnetic oscillations. This series is called a spectrum.Electromagnetic waves move in space at speeds close to 300,000 km/h. This is called the speed of light.
Color of light
Visible light is the part of the electromagnetic spectrum that our eyes can perceive. The light of the Sun or an ordinary light bulb consists of different colors. We can see these colors by refracting light using a prism. They are also visible in the rainbow in the sky.The colors are constantly mixed into one. At one end of the spectrum are red and orange. They gradually turn into yellow, green, blue, indigo and violet. Colors have different wavelengths, frequencies and energies. Purple with the shortest wavelength in the visible spectrum. This means it has the highest frequency and energy.
With red the opposite is true: the frequency and energy are the lowest, but the wavelength is the longest.
Light in the air
Light travels in space in a straight line until it encounters an obstacle in its path. When light moves through the atmosphere, it continues to move in a straight line until it hits air molecules. What happens after a collision depends on the wavelength and frequency.Dust particles and water droplets are much longer than the wavelength of visible light. Light, colliding with these particles, is reflected and changes its trajectory. Different colors of light are reflected equally from particles. The reflected light remains white, as it continues to contain all the colors mixed.
Gas molecules are much less length visible light waves. When light hits them, anything can happen. For example, it can be absorbed by molecules. And then they will begin to radiate it, but in the other direction. All colors are absorbed, but blue does this more strongly than all other colors. This process was called “Rayleigh scattering” (named after the English physicist Lord Rayleigh, who first discovered this phenomenon in 1870).
Why the sky is blue?
The sky is colored blue due to Rayleigh scattering. When light passes through the atmosphere, the blue color is absorbed by air molecules and reflected in different directions. This phenomenon is observed around the entire Earth. Wherever you look, the reflected blue color will catch you. That's why the whole sky looks blue.Near the horizon, the color of the sky is not so saturated, this is due to the fact that it has to pass through a larger volume of air.
Black sky and white sun
From Earth, the Sun appears yellow. If you find yourself in space or on the Moon, the Sun will turn white. There is no atmosphere in space and the light of the Sun is not reflected from anything. Without the atmosphere, the sky would look black.Why is the sunset red?
The sun is setting and the light will have to travel a long distance through the atmosphere before reaching you. Most of the light is reflected and absorbed. The less light reaches, the less bright the Sun appears. Its color varies from orange to red as these colors have the longest wavelength.Around the setting Sun, the sky can take on different colors.
It looks especially spectacular when there are many small particles suspended in the sky. They reflect light in different directions, turning the sky red, orange and pink.
Konstantin Mokanov
Everyone knows that depending on celestial point, in which we observe the Sun, its color can vary greatly.
For example, at 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 star 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 well-known saying about the hunter and the pheasant, with the help of which the color sequence is determined: 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 is scattered differently. For example, violet and blue scatter best, while red scatters worse. This phenomenon is called solar light dispersion.
The reason is that color is essentially an electromagnetic wave of a certain length. Accordingly, different waves have different lengths. And the eye perceives them depending on the thickness of the atmospheric air separating it from the light source, that is, the Sun.
Being at the zenith, it appears white because the sun's rays fall on the Earth's surface at right angles (meaning, of course, the place on the surface where the observer is located), and the thickness of the air, which affects the refraction of light, is relatively small. To a white person, it seems like a combination of all colors at once.
The sky, by the way, also appears blue due to the dispersion of light: since blue, violet and cyan colors, having the shortest wavelengths, are scattered in the atmosphere much faster than the rest of the spectrum. That is, by transmitting red, yellow and other rays with longer waves, atmospheric particles of water and dust scatter blue rays, which give the sky its color.
The further the Sun makes its usual daily journey and descends to the horizon, the greater the thickness of the atmospheric layer through which the sun's rays have to pass, and the more they are scattered. The most resistant to scattering is red, as it has the longest wavelength. Therefore, only it is perceived through the eyes of an observer who looks at the setting body. 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 the atmospheric air and the density of the suspension it contains. Vivid evidence of this can be observed in global emissions into the atmosphere of substances denser than air, for example, volcanic dust.
So, after 1883, when the famous eruption of the Krakatoa volcano occurred, for quite a long time in various places on the planet one could see red sunsets of extraordinary brightness.
>> Why is the sun red
Why does the sun turn red at sunset?: diagram of the movement of a star across the Earth’s sky, features of the planet’s atmosphere and the refraction of light, the red end of the spectrum.
Why is the sun red? Amazing question. After all, we could notice that often at sunset the Sun turns red, painting the sky in bloody shades. How does this happen and why is it red? The simplest answer is that light is refracted by particles in the atmosphere and all we see is the red end of the spectrum. To better understand, you should have a basic understanding of how light behaves in air, the composition of the atmosphere, the color of light, wavelengths, and Rayleigh scattering.
Atmosphere is one of the main factors in determining the color of a sunset. The earth's atmosphere is mainly composed of gases with the addition of other molecules. This affects what can be seen in every direction as the atmosphere completely surrounds the Earth. The most common gases are nitrogen (78%) and oxygen (21%). The one percent that remains consists of trace gases such as argon and water vapor, more fine solid elements such as dust, soot and ash, pollen, and salts from the oceans. There may be more water in the atmosphere after rain, or near the ocean. Volcanoes can eject large amounts of dust particles high into the atmosphere. Pollution can include a variety of gases, dust, and soot.
Then, you have to look at the light waves and the color of the light. Light is energy that travels in waves. Light is a wave of vibrating electric and magnetic fields, which is considered a particle of the electromagnetic range. Electromagnetic waves travel through space at the speed of light (299.792 km/sec). The emission energy depends on the wavelength and frequency.
The length of a wave is the distance between the peaks of the waves. Frequency is the number of waves that travel every second. The longer the wavelength of light, the lower the frequency, and the less energy it contains. Visible light is the part of the electromagnetic range that we see. The light from a light bulb may appear white, however, it is a combination of many colors. Rainbow is a natural prism effect. The tones of the spectrum are combined with each other and have different lengths waves, frequencies and energy. Violet has the shortest wavelength, meaning it has the most significant frequency and energy. Red has the longest wavelengths and the lowest frequency and energy.
To put this all together, we must look at the action of light in the air of our planet. What happens to light depends on the wavelength of the light and the size of the particles. Dust particles and water droplets are much larger than the wavelength of visible light, so they bounce in different directions. The light that is reflected appears white because it still contains all the same colors, but the gas molecules are smaller than the wavelength of visible light. When light hits them, it acts differently. Once a gas molecule hits the light, some of it can be absorbed. Later, the molecule emits light in different directions. The color that is emitted is the same that was absorbed. Different colors of light have different effects. All colors can be absorbed, but higher frequencies (blue) are absorbed more often than lower frequencies (red). This process is called Rayleigh scattering.
So, the answer to the question "Why is the Sun red?" next: At sunset, the light has to travel further through the atmosphere before it gets to you, so it reflects and scatters the most, and the Sun emerges from the darkness. The color of the Sun changes from orange to red because there are more blue and green waves now scattered and only the longer waves (orange and red) remain visible.
From red to violet, which are the main colors of the spectrum. The color visible to the eye is explained by the wavelength of light. Accordingly, red color gives the longest light, and violet gives the shortest.
During sunset, a person can observe a disk quickly approaching the horizon. At the same time, sunlight passes through an increasing thickness. The longer the light wavelength, the less susceptible it is to absorption by the atmospheric layer and the aerosol suspensions present in it. To explain this phenomenon, we need to consider the physical properties of blue and red colors, the usual shades of the sky.
When the sun is at its zenith, an observer can say that the sky is blue. This is due to differences in the optical properties of blue and red colors, namely their scattering and absorption abilities. Blue color is absorbed more strongly than red, but its ability to dissipate is much higher (four times) than that of red color. The ratio of wavelength to light intensity is a proven physical law called “Rayleigh’s blue sky law.”
When the sun is high, the layer of atmosphere and suspended matter separating the sky from the observer’s eyes is relatively small, the short wavelength of blue light is not completely absorbed, and the high scattering ability “drowns out” other colors. That's why the sky appears blue during the day.
When sunset comes, the sun begins to rapidly descend towards the true horizon, and the layer of 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 appear to the human eye in various shades of red, from orange to bright scarlet. It should be noted that the same thing is observed at sunrise and for the same reasons.
It's nice to look into the dazzling blue sky or enjoy the crimson sunset. Many people enjoy admiring the beauty of the world around them, but not everyone understands the nature of what they observe. In particular, it is difficult for them 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 appears bright blue. Why is this happening?
Scientists for several centuries could not explain the blue color of the sky. From a school physics course, everything that white light can be decomposed into its component colors using a prism. There is even a simple phrase for them: “Every Hunter Wants to Know Where the Pheasant Sits.” The initial words of this phrase allow you to remember the order of colors: red, yellow, green, blue, indigo, violet.
Scientists have suggested that the blue color of the sky is caused by 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 continued, and in 1899 Lord Rayleigh put forward a theory that finally answered 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 reaches the Earth's surface without interference, but most of them are absorbed by air molecules. By absorbing photons, air molecules become charged (excited) and then emit photons themselves. But these photons have a different wavelength, and photons that produce blue predominate among them. This is why the sky looks blue: the sunnier the day and the less cloudy it is, the more saturated this blue color of the sky becomes.
But if the sky is blue, then why does it turn crimson during sunset? The reason for this is very simple. The red component of the solar spectrum is absorbed much worse 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 right angle, closer to the poles it will decrease. As the Sun moves, the layer of air that light rays must pass through before reaching the observer’s eye increases - after all, the Sun is no longer overhead, but is leaning towards the horizon. A thick layer of air absorbs most of the rays of the solar spectrum, but red rays reach the observer almost without loss. This is why the sunset looks red.
On April 26, 2012, strange greenish clouds appeared in the sky over Moscow. An inexplicable phenomenon alarmed residents of the capital and agitated the Russian Internet. It was suggested that an accident occurred at one of the enterprises, which was accompanied by the release of harmful chemicals into the atmosphere. Fortunately, the information was not confirmed.
Instructions
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 anomalous phenomenon.
After a long winter, in early April there was a sharp warming, which caused rapid melting of the snow cover, early leafing out of trees and flowering of several species at once: birch, alder,