We see the sky every day. It is black in the night, white when there are clouds covering it, gray when the rain is not far away, but most of the time it is blue. But do you know what gives it this color? Why is the sky blue ?
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The atmosphere acts as a color filter
You should know that the light that illuminates the Earth comes from the Sun. The light in question is made up of the seven colors of the rainbow which are red, orange, yellow, green, blue, indigo and purple. And the mixture of all these colors gives white!
In addition to this detail, you should know that these different colors each have a different wavelength. These rays travel through the atmosphere differently. Once light passes through the atmosphere, it collides with the various molecules floating in it. In addition, the light is scattered in all collisions.
The warm and cold colors that cross our atmosphere
Warm colors easily pass through the earth’s atmosphere. Remember that the atmosphere is nothing other than the layer of air that surrounds and protects our planet. These warm colors are red, orange, yellow and green. They are directly absorbed by the Earth and therefore we do not perceive them.
On the other hand, cool colors like blue, indigo and purple do not easily pass through the air. They are dispersed in the atmosphere before reaching the ground. Shorter wavelengths like blue scatter more easily than other colors. Hence, the color of the sky which is blue!
What about the color of the sky at sunset and at night?
On the other hand, you might have noticed that the sky turns orange and red at sunset when it is low on the horizon. The reason is that the layer of atmosphere to be passed through is thick. Short wavelengths are also blocked by air and only long wavelengths, like red, can remain.
When it is dark, sunlight no longer interacts with the particles that make up the atmosphere. The sky has no more color … hence its darkness.