In astronomy, the sky is called the b-circle. From the surface it is imagined to be a mythical sphere where the sun, stars, moons and planets are seen to travel. B-sphere is usually divided into different constellations. Generally the word sky is used to indicate any point above the surface of the earth. But its meaning and usage may be different. For example, in the case of the sky, the sky refers to only the dense part of the lower atmosphere.
The sky looks blue for daylight light scattering. And at night, the sky looks like a black carpet full of stars. If there is no cloud during the day, there is sun in the sky. And in the night sky (sometimes in the day) the moon, planets and stars are visible. Natural phenomena such as clouds, raindrops, aurora or polar bear, thunder, etc. are observed in the sky.
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Due to the scattering of light the sky looks blue. When the particles are light, the particles spread in different light, which is the scattering of light. The less the light's wavelength, the greater the scattering of the light. Blue light wavelength is the lowest, so the sky is more scattering in the sky and the sky looks blue.
Cloud molecules are very large, and so they diffuse light beyond blue. As a result, the color of the cloud is white.
That is why the sky looks red at sunrise and sunset. At that time the sun stood near the horizon. So sunlight penetrates into the atmosphere of thick clouds. The blue light goes on different distances, but due to the red light wavelength it is less distracted and comes to earth. So the sky looks red again.
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