Why Is the Sky Blue?

Why Is the Sky Blue?

We can look up at the sky and see that the color is blue, many of us spend lovely spring and summer days laying in the grass and watching the white clouds float by in a beautiful blue sky. But what makes the sky a blue color?, Well to understand why the sky is blue we have to take a look at some of the things that make it appear blue.

The Atmosphere

The atmosphere is a mixture of molecules of gas water and dust that surround the earth. Depending on where you live, the atmosphere can contain more water near oceans or even more dust near volcanoes or deserts.

How Light Works?

Light is energy and depending on the type of light we have a variation in the size of the wavelength. Light is a wave of vibrating magnetic and electric fields there are many kinds of light and each one has a longer or shorter wavelength.

Why Is the Sky Blue?

Light is just one part of a larger group that is called the electromagnetic fields. The visible light which humans can see with their eyes is part of the electromagnetic field it’s actually made up of a stream of colors and these colors are the same in what we see in a rainbow.

Colors of the Rainbow

  1. Red
  2. Orange
  3. Yellow
  4. Green
  5. Blue
  6. Indigo
  7. Violet

When light travels, it is in a straight line and this is called the speed of light. It will continue to travel in a straight line until it bumps into something like a drop of water or dust. The next thing that happens depends on the size of the wavelength as well as the size of whatever it bumped into. Dust and water are larger than the wavelength of light so when it hits them it bounces off them and this is called reflection.

The light goes in many different directions and at this point the light still appears to be white because it still contains all of the same colors. Gas molecules are much smaller than visible light wavelength in this case when it gets hit by the gas molecules it acts totally different. When the light hits the gas molecules some of the light is absorbed by the molecule and when this happens the molecule gets full and it can begin to radiate or give off some of the color that was absorbed. Colors of light can be effected differently even though that all the colors have been absorbed.

Rayleigh Scattering

The higher frequency colors like blue are absorbed much faster than the lower frequency colors like red. This was a scientific process that was discovered and described in the 1870s by an English physicist called Lord John Rayleigh, because he discovered it he called it the Rayleigh scattering.

Color of the Sky

the process of why the sky looks blue is due to the process of Rayleigh scattering. When the light of the Sun goes through the air in our atmosphere almost none of the reds oranges or yellow portion of the light is affected by the air, but the Blues are absorbed and reflected.

Why Is the Sky Blue?

You can see when you look at the horizon in the distance it seems like the blue is getting lighter in color, this is because not enough of the blue light is being sent back or reflected to our eyes.

So now you know why the sky is blue and probably a little bit as well on light scattering.


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