Why is the sunset glow purple?

As we all know, sunlight consists of seven colors: red, orange, yellow, green, cyan, blue and purple. When sunlight enters the atmosphere and meets particles in the air, these colored lights will be dispersed, which is called scattering. Due to the different wavelengths of light waves, blue-violet light is scattered first, and red-orange light is scattered last.

During the day, the sun shines almost directly into the atmosphere, scattering more blue-violet light, blue is dominant, while red-orange light has less scattering and strong penetration, and shines directly on the ground. So the sky we see is blue. In the evening, the sun shines obliquely on the earth, and the light passes through the atmosphere thicker than noon. Blue-violet light first scatters in the atmosphere, and after reaching the ground, the remaining red, orange and yellow light scatter more, mainly red and orange light. These lights shine on the sky and clouds, forming a beautiful sunset glow.