What is a red sunset and why is it such a captivating color? Why is the sky blue during the day and red at night?

The crimson evening dawn will certainly remain in the memory of almost any person who managed to observe it. After all, even artists and photographers captured it in their works. And why the sun at sunset is red and not any other color is interesting to many.

What color is the celestial body?

It has been proven that the sun does not have a specific color. And its rays consist of many tones. The length of each electromagnetic wave corresponds a certain color. According to this length, human eyes distinguish between tones and halftones.

Thickness as well as density atmospheric air directly affect the overall color of the rays. But it's not that simple.

What is the reason that the sunset was scarlet?

The air is not homogeneous. It contains dust particles that are very fine. When the sun is located high, and the atmospheric layer, as well as the layer of various suspensions, is relatively small, the decomposition of the colors of the sun's rays, called dispersion, will not be significant. As it approaches the horizon, the thickness and density of the layers increases. Therefore, the dispersion becomes much more noticeable. Light is made up of a combination of tones. Each of them has a different ability to dissipate in the atmosphere and has different lengths electromagnetic wave.

All shades of red and orange are practically devoid of the ability to dissipate. Therefore, looking at the evening dawn, with strong dispersion, the entire set of tones of the sun's rays becomes practically invisible when absorbed by the aerosol suspension of air. And only the scarlet tone remains visible.

This explains why the sunset is red and not yellow, for example. At sunrise exactly the same thing occurs and for similar reasons.

What weather does it foretell?

Many natural phenomena describe the signs by which people lived tens and even hundreds of years ago. They compiled a so-called set of rules and passed it on from generation to generation. After all, people’s lives throughout the year depended on what the weather would be like, and therefore the harvest of vegetables and berries. Thanks to their observations, you can find out what a red sunset means and what it portends. The following are the most famous signs:

1. If the sunset light is purple, it means windy weather is expected tomorrow.
2. If the sky turns scarlet only after sunset, it means there will be bad weather in a day or two.
3. If there are reddish clouds opposite the evening dawn, it will rain.
4. If the sky turns crimson when the light is still high at sunset, there will be bad weather in the evening of the same day.
5. If there are no clouds at sunrise, when the heavenly body sets with a light scarlet dawn, you can expect clear weather.
6. If the sun sets big and bright scarlet, then tomorrow you can expect good weather.
7. If during the evening dawn in summer the sky turns purple on the northern side, frost is expected.

These patterns were noticed and remembered by people in the old days. Yes, they had not heard about dispersion and why this happens, but they knew a lot about the red sunset signs.

Enjoy the beauty of the purple sunset of the heavenly body. Observe how this process goes and what is accompanied by it. Then perhaps you will be able to predict what he portends.

Sometimes at night we have the opportunity to observe a phenomenon in which the sky seems not dark enough. And today we will look at questions about why the sky is bright at night.

Why is it light at night in winter?

IN winter period year, we are accustomed not only to the fact that it begins to get dark much earlier than in summer, but also to the fact that the weather is usually such that even in the daytime the daylight hours seem less bright. Despite this, sometimes we have the opportunity to observe quite bright nights, therefore, we need to consider the question of why the sky at night is bright in winter.

There may be two reasons for a lighter sky at night:

• If you notice that the night is not as dark as always, and there is precipitation in the form of snow outside, you can be sure that the snow is the reason for such a bright sky. Snowflakes reflect the light of lanterns, as well as moonlight, thereby creating the illusion of a more illuminated night sky;
• If the sky is bright enough and there is no precipitation, then the cause of this phenomenon can be considered strong and low cloudiness. Pay attention to the clouds - they are lower than usual. For this reason, clouds act as reflectors of light from the earth, which leads to the illusion of a bright sky.

Why is it as bright as day at night?

If, when wondering about the night illumination of the Earth’s surface, you were directly interested in information about the so-called “White Nights”, which are observed, for example, in St. Petersburg, then in this situation the answer will be completely different.

To begin with, it is worth noting that such white nights are observed not only in St. Petersburg, but also in many other parts of our planet. For example, it is quite possible that someone will be interested in the question of why it is light at night in Greenland, since a similar phenomenon is also present there.

Events on a planetary scale are considered to be to blame for the occurrence of such a phenomenon. The point is that in certain moment time, due to the fact that the Earth rotates around the Sun along a certain trajectory, and also rotates around its own axis, our planet is on such a trajectory that even at night the Sun in the territory of, for example, St. Petersburg or Greenland does not set much lower horizon lines. Accordingly, even at night sunlight dissipates over the surface of the Earth and in the above-mentioned territories a kind of twilight is observed instead of the usual night.

The world around us is full of amazing wonders, but we often do not pay attention to them. Admiring the clear blue of the spring sky or the bright colors of the sunset, we don’t even think about why the sky changes color as the time of day changes.


We are accustomed to the bright blue on a fine sunny day and to the fact that in the fall the sky becomes hazy gray, losing its bright colors. But if you ask modern man about why this happens, then the vast majority of us, once armed with school knowledge of physics, are unlikely to be able to answer this simple question. Meanwhile, there is nothing complicated in the explanation.

What is color?

From school course As physicists, we should know that differences in the color perception of objects depend on the wavelength of light. Our eye is able to distinguish only a fairly narrow range of wave radiation, with the shortest waves being blue and the longest being red. Between these two primary colors lies our entire palette of color perception, expressed by wave radiation in different ranges.

A white ray of sunlight actually consists of waves of all color ranges, which is easy to see by passing it through a glass prism - you probably remember this school experience. In order to remember the sequence of changes in wavelengths, i.e. sequence of colors of the daylight spectrum, a funny phrase about a hunter was invented, which each of us learned at school: Every Hunter Wants to Know, etc.


Since red light waves are the longest, they are less susceptible to scattering when passing through. Therefore, when you need to visually highlight an object, they use predominantly red color, which is clearly visible from afar in any weather.

Therefore, a prohibitory traffic light or any other danger warning light is red, not green or Blue colour.

Why does the sky turn red at sunset?

IN evening hours Before sunset, the sun's rays hit the earth's surface at an angle rather than straight on. They have to overcome a much thicker layer of atmosphere than in the daytime, when the surface of the earth is illuminated by the direct rays of the Sun.

At this time, the atmosphere acts as a color filter, which scatters rays from almost the entire visible range, except for red ones - the longest and therefore most resistant to interference. All other light waves are either scattered or absorbed by particles of water vapor and dust present in the atmosphere.

The lower the Sun falls relative to the horizon, the thicker the layer of atmosphere the light rays have to overcome. Therefore, their color is increasingly shifting towards the red part of the spectrum. Associated with this phenomenon folk sign, indicating that a red sunset portends strong wind the next day.


The wind originates in high layers of the atmosphere and at a great distance from the observer. Oblique rays of the sun highlight the emerging zone of atmospheric radiation, in which there is much more dust and vapor than in a calm atmosphere. Therefore, before a windy day we see a particularly red, bright sunset.

Why is the sky blue during the day?

Differences in light wavelengths also explain the clear blue of the daytime sky. When the sun's rays fall directly on the surface of the earth, the layer of atmosphere they overcome has the smallest thickness.

Scattering of light waves occurs when they collide with the molecules of gases that make up the air, and in this situation, the short-wavelength light range turns out to be the most stable, i.e. blue and violet light waves. On a fine windless day the sky takes on amazing depth and blue. But why do we then see blue and not purple sky?

The fact is that the cells in the human eye that are responsible for color perception perceive blue much better than violet. Still, violet is too close to the border of the perception range.

This is why we see the sky bright blue if there are no scattering components in the atmosphere other than air molecules. When a sufficiently large amount of dust appears in the atmosphere - for example, in a hot summer in the city - the sky seems to fade, losing its bright blue.

Gray sky of bad weather

Now it’s clear why autumn bad weather and winter slush make the sky hopelessly gray. A large number of water vapor in the atmosphere leads to the scattering of all components of a white light beam without exception. Light rays are crushed into tiny droplets and water molecules, losing their direction and mixing throughout the entire range of the spectrum.


Therefore, light rays reach the surface as if passed through a giant scattering lampshade. We perceive this phenomenon as the grayish-white color of the sky. As soon as moisture is removed from the atmosphere, the sky again becomes bright blue.