Topic: Tyndall Effect
Why does the sky appear blue?
It is such a beautiful rainbow.
Have you ever wondered, how it is formed?
A rainbow is formed when raindrops split sunlight into different colors.
Sunlight or white light consists of many colors.
However, only a few of them are visible to us.
A band of these visible colors is called a visible spectrum.
When we see a rainbow, our brain and eyes distinguish the visible spectrum into seven main colors, namely red, orange, yellow, green, blue, indigo and violet.
Hey.
Did you notice that the size of the balls increased?
Yes, you guessed right.
The balls represent the different colors of a rainbow in increasing order of their wavelengths.
Wavelength is the distance between consecutive crests or consecutive troughs in a wave.
In a rainbow, as we move from violet to red, the wavelength of colors increases.
Violet has the shortest wavelength while red has the longest wavelength.
Do you think that our eyes have a natural inclination towards blue as compared to violet?
Yes, this is one of the reasons why our sky appears blue and not violet.
To understand this, first let us study about Tyndall effect.
Tyndall effect is a phenomenon in which a beam of light scatters on striking the particles present in its path.
This scattering of light is responsible for the blue color of the sky.
We know that our atmosphere primarily consists of oxygen and nitrogen particles along with dust, smoke and other particles in comparatively smaller proportions.
The size of these particles in the atmosphere is responsible for the color of scattered light.
When the sunlight strikes particles of dust,smoke, etc., which are bigger than the wavelength of sunlight, all the colors of sunlight are equally scattered.
As a result, the scattered light appears white.
However, when the sunlight strikes particles of oxygen and nitrogen which are smaller than the wavelength of sunlight, the colors of sunlight having shorter wavelengths, that is, blue and violet are much more scattered than colors having longer wavelengths.
But our eyes are much more sensitive to blue color as compared to violet, hence the sky appears blue to us.