Why are overcast skies gray and clear skies blue?

2024 Author: Henry Conors | [email protected]. Last modified: 2024-02-12 02:43

The beauty of the sky has been depicted more than once by artists, described by writers and poets, even people who are very far from art stare into this alluring abyss, admire it, not finding either words or sufficient emotions to express those feelings that stir the soul and mind. Height attracts a person in any role, it is beautiful with its crystal blue surface, no less attractive are its seething streams of white-gray clouds, replaced by light interspersed with cirrus clouds or lush cumulus "lambs". And no matter how melancholy the cloudy sky may look, enveloping with its depth, deafening and crushing with its whole mass, it also causes a storm of emotions and experiences, casting thoughts on a special wave.

Beauty is seen by the beholder

Every person perceives the world differently. For some, it is gloomy and gray, while others, on the contrary, see only a blooming, green, full of colors planet. We also value the heavens above our heads differently. If we take into account a person with ordinary color perception, then he will see the sky as it is commonly believed - blue, gray, pinkish at sunset, smoky-gray at dawn.

In fact, these paints -it is only what our eyes and brain can convey to us. It is easiest for people to perceive an overcast sky as gray. In clear weather, we have endless azure above our heads, but in fact, the atmospheric dome is closer to a purple hue when viewed from the side of the Earth.

In this publication, we will find out why the sky on a cloudy day is gray and what determines the saturation of this color, we will also find out how its color changes throughout the day and year and what affects these processes.

The bottomless ocean above

Above the territory of European countries, the sky in the warm season usually strikes with its rich blue tint. Sometimes you can say about it that it is blue-blue. However, if you give even one day to what is happening above our heads and carefully observe natural processes, you will notice a gradation of color that changes very much from the moment the sun rises until the moment it completely sets.

In summer, the sky seems so clear and visually high due to low humidity, the absence of a large number of clouds, which, accumulating water, gradually sink closer to the ground. In clear weather, our gaze does not even look at hundreds of meters ahead, but at a distance equal to 1-1.5 km. Therefore, we perceive the sky as high and bright - the absence of interference in the path of light rays in the atmosphere helps to ensure that they do not refract, and the eyes perceive its color as blue.

Why does the sky change color

Such a change is described by science, however, not as picturesque as by writers, and is called diffuse radiation of the sky. If we speak in a simple and accessible language for the reader, then the processes of color formation of the heavens can be explained as follows. The light that the sun emits passes through the air gap around the Earth, it scatters it. This process is easier with short wavelengths. During the maximum rise of the celestial body above our planet, at a point located outside its direction, the brightest and most saturated blue color will be observed.

However, when the sun sets or rises, its rays pass tangentially to the surface of the Earth, the light emitted by them needs to travel a longer path, which means they are scattered in the air to a much greater extent than during the day. As a result, a person perceives the sky in pink and red colors in the morning and evening. This phenomenon is most visible when there is an overcast sky above us. Clouds and clouds then become very bright, the glow of the setting sun colors them in stunning crimson colors.

Thundersteel

But what is an overcast sky? Why does it become like this? This phenomenon is one of the links in the water cycle in nature. Rising up in the form of steam, water particles enter the atmospheric layer with a lower temperature. Accumulating and cooling at high altitude, they combine with each other, turning into drops. At the moment when these particles are still very small, beautiful white cumulus clouds appear to our eyes. However, the larger the drops become,the more in the clouds of gray.

Sometimes, looking at the sky, through which these huge "lambs" float, you can see that one part of them is painted gray, others even acquire a steel thunder hue. This transformation is explained by the fact that the drops in the clouds have different sizes and shapes, so they refract light in different ways. When the sky is completely overcast, it is all mouse gray, and only white light reaches us.

Enormous smoky expanses

There are days when the gray overcast sky has not a single gap. This happens when the concentration of clouds and clouds is very high, they envelop the entire visual space in the sky. Sometimes they are perceived as a huge pressing mass, ready to fall on the head. Moreover, this phenomenon is most typical in autumn and winter, when the air temperature is low, but the humidity, on the contrary, is high and is at the level of 80-90%.

On such days, the clouds are very close to the earth's surface, they are located only a hundred or two meters from it. The description of an overcast sky often has melancholy and depressing notes, and this is most likely due to precisely the sensations that arise when you feel alone with this gloomy hulk, ready to fall down on you with rain and cold.

It could have been different…

The color of the sky depends on the intensity of the light radiation and the wavelength reaching the planet, so in winter, even on clear days, it is bluish-blue. But the closer spring is and the higher the position of the sun, the brighter its blue, especially on days when haze dissipates in the upper atmosphere, distorting the light.

Scientists have found that on other planets the sky may not have the usual blue and gray colors for us, on Mars, for example, it is pink even at the height of daylight.