Why does the sky turn red at sunset?

 Why is the sky/atmosphere blue during the day?

 Why is the sky/space reddish in color at sunrise and sunset?

 Light: Light is an electromagnetic radiation that travels in the form of waves. It originates from any source in different forms.

 Visible spectrum of light:

 Electromagnetic waves can be in different wavelengths, such waves of light whose wavelength is between 400 ~ nanometers to 750 ~ nanometers, their overall spectrum is called the visible wave spectrum of light.

 Waves of light whose wavelength is between 400 nanometers and 700 nanometers disturb our brain in a way that can be seen, this wavelength is called the visible spectrum of light.

The color:

 Color is the conscious recognition of the mind formed in the brain. It is actually created by the variation of the wavelength of light that our brain distinguishes as different colors.  Color is a recognition of disturbances in our brains caused by changes in the wavelength of light.

All physical objects are actually colorless, they have no color of their own, the whole universe is actually colorless.

 The answer to why we see a rose leaf red is that at the smallest atomic level, its structure is such that when light waves hit it, the basic particles of the leaf's structure where at that level are having 670 nanometers ups and downs (in simple way to understand).  They reflect without any effect on the waves with wavelengths from 1000 to 700 nanometers and absorb all other wavelengths, these waves with wavelengths from 670 nanometers to 700 nanometers,put an affact to our brain recognizes red as the color and we see this leaf red.

 Scattering of light:

 When light hits a particle or surface whose volume is less than or equal to the wavelength of light, then the light waves are scattered in all directions after colliding with the particle or being absorbed, it is called scattering of light waves.

 Why is the color of the sky blue during the day?

 Our atmosphere consists of many gas molecules, these gases include nitrogen, oxygen and argon gases. Nitrogen gas is the most abundant gas in the atmosphere. Its molecular size is about 0.3 nanometers.  Spectral white light (wavelengths from 400~ nanometers to 700~ nanometers) hits air molecules, while light waves of longer wavelengths are less likely to hit air molecules due to their very small volume.  While waves with shorter wavelengths are absorbed to a greater extent by collisions with these air molecules and scatter more than waves with longer wavelengths, the wavelengths of 400 to 450 nanometers.  Due to its short wavelength, it scatters more and reaches our eyes more, so we see the sky in blue color (400 to 450 nanometer wavelength).

Why does the sky turn red at sunset?

 When the Sun is near the horizon from our point of view, the amount of space between it and us is greater than at any other point of the Sun position, so the process of light scattering is more frequent and greater, and the blue light  The light of the other colors also undergoes a sufficient amount of scattering compared to the wavelengths, which increases the amount of scattering of yellow, yellowish, red and reddish light waves in the atmosphere, due to which we see the sky blue.  Instead it looks reddish.

 Since clouds are a large collection of water vapor, they can contain water vapor of varying volumes in the form of very small water droplets that scatter all the waves of light coming from the sun equally.  They look white to us.