KNOXVILLE, Tenn. (WATE) — Why are some sunsets brighter than others? Why is the sky blue? It all has to do due with optics and the light spectrum.
Starting off with the basics. When a beam of sunlight hits an air molecule in the sky, molecules scatter colors in all directions. Around noon when the sun is directly above the Earth and passing through a smaller portion of Earth’s atmosphere, it’s causing all the wavelengths of light to be scattered equally. Blue light scatters more effectively due to a shorter wavelength than red light, making the sky appear blue. when looking away from the sun.
At sunrise and sunset, the sunlight is passing through more of the Earth’s atmosphere. When that happens, blue wavelengths of light are scattered out more leaving reds and oranges. That’s why during sunrise and sunset you tend to see the sky and sun look a little more orange.
In addition to air molecules, dust and pollution in the atmosphere have an impact on why we see certain colors. A dust molecule or pollution molecule tends to absorb more wavelengths of light, making the sky look dimmer.
When there is a large amount of dust or pollution in the sky, the sunset is going to be more of a deeper red color because those dust molecules are absorbing more wavelengths of light. When the sky is clear, the colors are going to appear brighter and the colors will appear more vibrant.