Every day, we look up at the sky and see it in all its blue glory; yet we may not know why it is blue rather than other colors. In this video, we will dive into every detail that determines the color of the sky. The causes are divided into three parts, namely light waves, the scattering of sunlight, and the reason why we interpret the sky as blue instead of violet.
The first factor is the light waves. There are different colors of light waves with different wavelengths in the visible light region of the electromagnetic spectrum, mainly violet, indigo, blue, green, yellow, orange, and red. Violet light waves have the shortest wavelengths among all, while red light waves have the longest wavelength.
The second factor is the scattering of sunlight. The Sun shines white light, which is a combination of all seven colors of light waves. Light waves from the Sun bounce off from air molecules, which is a process called Rayleigh scattering. Because air molecules are much smaller than the wavelengths of the light, collisions cause the longer wavelengths to scatter less
compared to that of the shorter ones. As a result, light of shorter wavelengths scatter more than longer ones. As the wavelengths of light increase, their frequency and thus energy decrease. The light waves with the lowest energy refract the least, while light waves with the highest
energy exhibit the greatest refraction. Upon entering the atmosphere and coming in contact with air molecules, sunlight, originally white, scatters into seven different colors. With violet having the shortest wavelengths, meaning that they are the most energetic, they tend to overpower the
other colors of light waves, thus taking control of the color of the sky.
The third factor we discussed is why we interpret the sky as blue instead of violet. The retinas of our eyes have color-sensitive cells, which are known as cones. Cones are divided into three types, namely red, blue, and green. Each type of cones is sensitive to a specific color of light wave. When we look at something and its light strikes our retina, the cones allow our brain to determine the colors we see. These colors correspond to the actual color light waves we see. While each type of cone has its peak sensitivity for red, blue, or light, they can also detect light of other colors. When violet light waves strike the retina, red cones are the most stimulated cone
cells, allowing us to see red within violet. The greenish tinge and reddish tinge are washed out when blue and violet lights are combined. As a result, we can see blue instead of violet.
Through this video, we aim to explain the phenomenon of why the sky appears blue to the audience. By understanding the intricate details of this phenomenon, we hope to spark the audience’s curiosity and deepen their appreciation of the beauty of nature.
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