There is nothing more beautiful than starting the day with a totally clear sky, of a beautiful blue color, right? Surely you have ever wondered why it has that characteristic color and not another. It could be said, without mistake, that it is the million dollar question you need an answer soon.
As well. In this article I will explain Why is the sky blue so that from now on, every time you look up at the sky, you know why we see it in that tonality.
The blue color of the sky
The simplest explanation for why the sky is blue is the following: this color is due to the interaction of white light that comes from the Sun with molecules found in the air. However, the color that results from the interaction between the white light of the Sun and the molecules does not have to be blue. In fact, as the hours go by, the sky presents different shades and colors in the sky. This is due to the rotational and translational movements of the Earth and the different changes that occur in the whole of the air in the atmosphere. But there is still more ...
Once the white light from the sun 'passes through' the atmosphere, it disperses into all its colors: short-wave (blue and violet) and long-wave (red and yellow). As blue and violet colored rays have a maximum deviation, they disperse more and more before reaching the ground that we tread. When they reach our eyes, we have the sensation that they occupy the entire sky when they really come directly from our star: the sun.
This is the explanation of why in deep space the sky is completely black. As there are no air particles that can refract in sunlight, you cannot distinguish the different colors that the sky from outer space is likely to have.
Visible spectrum of light
To better understand this explanation, I think it is convenient to explain what is the visible spectrum of light and how important is it on the subject we are dealing with.
The eyes of human beings are a real wonder (yes, even if you have to wear contact lenses 😉), since can distinguish a wide variety of colors ranging from ultraviolet -which has a wavelength of 400nm-, to infrared -750nm-. These waves are known as visible light, that is, we see an object, or in this case the sky, that is being illuminated by something (the sun).
Depending on the wavelength, we will see it in one color or another. When we see it blue, it is because we are perceiving waves from between 435 and 500nm. But if you want to know what wavelengths each color has, maybe this will help you:
625 - 740: Red
590 - 625: Orange
565 - 590: Yellow
520 - 565: Green
500 - 520: Cyan
435 - 500: Blue
380 - 435: Violet
Not all animals see the world the same color as us. So much so that dogs, for example, do not distinguish red or green. Each species has its own spectrum of colors, depending on how important vision is to her.
The other sky colors
Although we might think that the sky can only be seen in different shades of blue, in reality sometimes we will see it in other colors. And it is that under some certain circumstances phenomena such as rainbow, solar crowns and halos of light.
As if it were a prism, white light reaching the atmosphere causes different wavelengths, which sometimes causes the sky to produce phenomena as wonderful as those mentioned in the previous paragraph. Although, of course, in this case there are no prisms, but particles of water.
And by the way, do you know why sometimes the sky looks red or orange? No? Nothing happens. Here's the explanation: this happens especially at sunset. It is because the sun's rays at those times have to travel a greater distance than in the central hours of the day to reach us. First it looks like orange and then red, since the short wavelengths (which, as we have seen, are bluish and violet colors) are increasingly dispersed and only long lengths reach us (red).
If in the afternoon we have a cloudy sky, the rays of the sun will illuminate the clouds from the bottom, which in turn will be perceived by our eyes. Keep in mind that the sky will not be looking increasingly red, but the blue color will fade as it is dispersed by air particles. Interesting, don't you think?
Now you know why the sky is blue ... or, well, other colors too 🙂.
Hi albi.
Clouds are made up of drops of water. The color varies depending on the size of these drops and the sun; For example, if they are large, our eyes will see them gray or black because the clouds block the passage of the sun's rays towards the earth.
As for the Moon, well, actually our satellite is made up of dark material; however, the space is much blacker. Thus, being surrounded by complete darkness it seems to us that it is white, especially on nights with a full moon.
An interesting fact is that human eyes are sensitive to light, being made up of rods and cones. Thanks to the former we can distinguish colors, as long as there is enough light; the opposite happens with seconds, that is, they detect light, but colors ... not so much.
But why do the clouds look white? And the moon too! Why?
Hi albi.
Clouds are made up of drops of water. The color varies depending on the size of these drops and the sun; For example, if they are large, our eyes will see them gray or black because the clouds block the passage of the sun's rays towards the earth.
As for the Moon, well, actually our satellite is made up of dark material; however, the space is much blacker. Thus, being surrounded by complete darkness it seems to us that it is white, especially on nights with a full moon.
An interesting fact is that human eyes are sensitive to light, being made up of rods and cones. Thanks to the former we can distinguish colors, as long as there is enough light; the opposite happens with seconds, that is, they detect light, but colors ... not so much.