Why is the sky blue and sunsets colorful?

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The sky appears blue, and sunsets are colorful due to a phenomenon known as Rayleigh scattering. Here is the explanation:

1. Why is the sky blue?

Sunlight is made up of different colors that together produce white light. When the sunlight hits the earth’s atmosphere, it is scattered by the molecules in the air (mainly nitrogen and oxygen).
The scattering depends on the wavelength: Short-wave light (blue and violet) is scattered more strongly than long-wave light (red, orange, yellow).
Although violet light is scattered even more than blue light, we perceive the sky as blue because our eyes are more sensitive to blue light, and the violet light is partially absorbed in the upper atmosphere.

2. Why are sunsets colorful?

At sunrises and sunsets, the sun is lower on the horizon, so light has to travel a longer distance through the atmosphere.
On this longer path, the short-wave blue light is scattered so much that it barely reaches our eyes. The long-wave light (red, orange, yellow) is scattered less and therefore dominates the sky.
In addition, dust, clouds and other particles in the atmosphere can further scatter and reflect the light, resulting in the intense colors of sunsets.

The sky is blue because blue light is more scattered, and sunsets are colorful because the blue light is filtered out on the longer path through the atmosphere, and the warm colors dominate.