Interesting Information

During the day (daylight) the sky has a blue appearance because the Sun’s light (white light) is made up of rainbow of colors (red, orange, yellow, green, blue, indigo and violet) of different wavelength. This means, all these different colors of light combine to give you what is called white light (see diagram: refraction of sunlight). When sunlight enters the Earth’s atmosphere, it collides with air particles that causes the scattering of sunlight around the sky. The light with the shorter wavelength is scattered more by this collision than light with longer wavelengths. In this case, violet light is scattered the most, but human eyes do not see this color very well. However, since the human eyes are more sensitive to blue light (the next most scattered visible color), you will see the sky as blue. This therefore means that the blueness of the sky is from the blue light that is scattered from the sunlight in the atmosphere which, then enters our eyes from all regions of the sky.

To explain why the sky is blue we will need to take a quick look at the Sun and the atmosphere in understanding the role they play in the sky appearing blue. Light from the sun (sunlight) is composed of seven colors (rainbow colors) of different wavelength* that blend perfectly to make the sun’s light white in appearance. This light from the Sun is called white light. The different colors in sunlight (white light) can be seen by passing sunlight through a prism (see diagram below). When sunlight (white light) is allowed to pass through a prism, it scatters the different colors of light according to their wavelength, showing a continuous band of colors. This procedure exhibits the range (visible light spectrum) of colors - red, orange, yellow, green, blue, indigo, and violet in that order. This means that the different colors of light have different wavelengths in which red light has the longest wavelength and blue light found at the other end of the visible