Without even suspecting the complexity, your eyes perceive more than 200 colors, easily distinguish the most subtle nuances and recognize more than 20 degrees of saturation and 500 levels of brightness.

The result? Every day, our eyes receive and assimilate millions of colorful stimuli - a prodigious universe of colors, often breathtaking. But how does it work? Why does the sky blue or red at times, and gray at others? And what is the relationship between the manufacture of sunglasses?

Thanks to a certain type of photo-receivers, the cones that you perceive in colors

Your eyes are equipped with two kinds of photosensitive cells: cones and sticks. These two types of retinal photoreceptors share the work: the rods ensure the perception of changes in light intensity, up to a certain degree of luminosity. The sticks play a key role in night vision. They guarantee you an optimal vision, in broad daylight as in the dim light. The cones, meanwhile, ensure the perception of colors. There are three types, each of which reacts to a certain wavelength.

What concrete role do these different cones play in your perception of colors? - If for example, a surface reflects only short waves, this surface will be identified as blue by your brain. If it reflects, on the contrary, only the long waves, you will see it red. The reflection of medium waves causes the perception of the green color. It is when a given surface reflects different wavelengths that you perceive mixed colors like yellow, purple, purple or orange. Finally, if your cones react simultaneously to waves of any length, your brain identifies the white color.

That being said, another decisive factor comes into play in the perception of colors: objects and surfaces not only reflect colors, but they also absorb them too! A ripe cherry, for example, owes its ravishing color to the fact that its skin absorbs the blue and green lights, to reflect only the long light waves, that is to say, the red color. The colors you perceive are therefore determined by the proportion and intensity of the three types of light waves (blue, green, red) absorbed or reflected.

The human eye detects a visible spectrum between 380 and 780 nanometers. It can't perceive the light waves of shorter length (ultraviolet or UV) and higher (infrared) at the limits of this visible spectrum.

Why is the sky blue?

Sunlight is white because it contains light waves of any length, in equal proportions. Using a prism, it is easy to diffract a sunbeam and identify all the colors it contains.

When the sun is at its zenith, its rays have no difficulty in crossing the atmosphere to you. When they enter the atmosphere, only a small part of the rays of blue light is absorbed: that is why the sun is yellow. As for the sky, it looks blue precisely because the path of light rays in the atmosphere is relatively short. Molecules in the atmosphere, such as oxygen and nitrogen, deflect rays of light in all directions. The blue light, which corresponds to a shortwave, deviates and diffuses more easily than the long waves of the red light.

It is because of this important diffusion of blue light that the sky takes on its blue color. If the sun is low, like at dawn or dusk, the path of the sun's rays into the atmosphere is longer. Only the long waves of red light reach you. The sky then takes on a red color. If the weather is overcast, or if the air is dusty, the sun's rays are reflected in full, instead of being diffracted according to their wavelengths. The sky is then white, or gray if the weather is really bad. Unlike the earth, the moon has no atmosphere. The moon sky is black because sunlight reaches the surface of the planet without undergoing any deviation.

For the same reason, if you are on the moon, you will perceive the bright white sun. The sky then takes on a red color. If the weather is overcast, or if the air is dusty, the sun's rays are reflected in full, instead of being diffracted according to their wavelengths. The sky is then white, or gray if the weather is really bad. Unlike the earth, the moon has no atmosphere.

The moon sky is black because sunlight reaches the surface of the planet without undergoing any deviation. For the same reason, if you are on the moon, you will perceive the bright white sun. The sky then takes on a red color. If the weather is overcast, or if the air is dusty, the sun's rays are reflected in full, instead of being diffracted according to their wavelengths.

The sky is then white, or gray if the weather is really bad. Unlike the earth, the moon has no atmosphere. The moon sky is black because sunlight reaches the surface of the planet without undergoing any deviation. For the same reason, if you are on the moon, you will perceive the bright white sun. Unlike the earth, the moon has no atmosphere. The moon sky is black because sunlight reaches the surface of the planet without undergoing any deviation.

For the same reason, if you are on the moon, you will perceive the bright white sun. Unlike the earth, the moon has no atmosphere. The moon sky is black because sunlight reaches the surface of the planet without undergoing any deviation. For the same reason, if you are on the moon, you will perceive the bright white sun.

What do sunglasses do for your eyes?

Sunglasses are more than just a fashion accessory. They protect your eyes from shortwave ultraviolet radiation, invisible but very harmful. By reducing the inconvenience associated with the glare of the sun, they also considerably improve your comfort of view. The more intense the sunlight, and the more reflective surfaces such as water or snow, the more important it is to protect your eyes. It is therefore recommended to opt for darker glasses. Specific treatments may be useful in the most extreme conditions.

Generally, the hue of your sunglasses is neutral, the less they influence your perception of colors. Good sunglasses should ideally dim the light while allowing you to maintain a natural perception of the entire color spectrum. This issue is decisive for sunglasses for driving or a two-wheeler. When acquiring your sunglasses, be sure to opt for lenses suitable for driving. Avoid shades that are too dark, high absorption. They could alter your perception of signal lights. Some colors, such as dark blue or red, can't be worn behind the wheel. In addition, solar absorption lenses above 25% are not suitable for driving at night or in low light conditions. When driving, be careful - be sure to consider these factors! Your Optician will be happy to provide you with further details on this subject.

In some cases - for both aesthetic and practical reasons - classic shades such as gray, brown and dark green are inadequate. Zeelool sunglasses and Lenses are available in the shade of your choice. Depending on the color chosen, your natural perception of colors will be more or less altered. After a while, however, your eyes will adapt to the filter and your brain will spontaneously restore the natural colors.

There are many myths about how a particular shade of glasses can affect your eyesight or mood. The fact is that the positive or negative effects of a certain hue vary considerably between people. Do not hesitate to try several shades at your optician!

How do sunglasses improve contrasts?

As we have just shown, the sun's rays are deflected as they pass through the atmosphere in all directions. Because of the action of the particles present in the atmosphere, it is the blue light that is most reflective: that is why the sky appears blue when the sun shines. Skylet sunglasses are specifically treated to filter out some of the blue light, and thus significantly improve your contrast vision. All the art is to mitigate the share of blue light just enough for the colors to stay natural. Skylet lenses from Zeiss do not include a blue blocker that would completely filter out any blue light.

Interesting fact: If you have a visual red-green weakness (without being color blind), Skylet sunglasses can improve your vision.

Published by Calida Jenkins