By Jacque Scott

Why is the Sky Blue?

I was looking back at some of my old columns from 2006.  I started writing for The Messenger in April of that year and my columns have slowly evolved into what you see today.  The very first column was called “Why is the Sky Blue” and I’ll reprint it for you.

You’ll see that at that time I was still working as a nurse and only had 2 grandchilren.  Today I am retired, married to a wonderful man and have 9 grandchildren.  Time flies when you’re having fun…  So here goes…

Ever wonder why something is like it is?  How something came to be like it is?  How it all started?  The small child in each of us wants to know why, why, why………I’ve done a bit of research and from week to week will try to share some of the answers I have found.

First of all, let me tell you a little about myself. I am a nurse, a mother of six and grandmother of two. We moved to East Texas in the late 90’s and found that there is no finer or beautiful place  to raise children. Three of my six still live in the Palestine area.

So let’s start with something as simple sounding as ‘Why is the sky blue?’ A famous scientist, John Tyndall, shed some light on this age old question in the late 1800’s.

Tyndall explained that the sun is almost 93 million miles away, and its white rays come to the earth in a straight line until they hit the earth’s atmosphere. The rays are absorbed by the atmosphere and are turned into beautiful colors like a prism. Our atmosphere is full of dust particles which catch and break up the light rays, throwing back all of the colors except the blue ones. What happens to the light depends on its wave length and the size of the thing it hits.

When the light hits these large particles of dust and water droplets, the different colors of light all appear white when reflected.  Gas molecules are smaller.  When light hits them, light gets absorbed and after a while the molecule releases some of the light. All colors can be absorbed but blue ones are absorbed more than red ones. This process is called Rayleigh scattering after an English physicist, named Lord John Rayleigh, who described it in the late 1800’s.

The blue sky color happens when the light moves through the atmosphere because very little of the other colors are affected by air. The blue light scatters when it passes through a lot of air, and goes in many directions. The color of blue is lightest near the horizon because it has been scattered and so appears paler or whiter than the rest of the sky.

When the sky is gray, it is because the earth dust is coated with vapor or water dust, and vapor is not a good reflector.  We cannot have a blue sky until the water vapor has condensed and fallen as rain.

So, there you have it, a simple answer to an old question.  Please feel free to write me in care of the Messenger about any of the ’Wonder Why’s’ you might have.  I will try my best to find some of the answers for you.  God bless you.