Why is the sky Blue?
As anyone who has studied this issue will tell you, the sky isn’t really blue. In fact, there isn’t a sky in the true sense of the word. Sorry, there is no bowl of beautiful blue that gets darker when the sun drops below the horizon.
So, what’s the answer to the question posed in our title? The solution to the riddle involves sunlight and the chemicals that make up the atmosphere. The thing that makes the atmosphere look blue to our eyes is called scattering. Light from the sun passes through oxygen, nitrogen and other elements that breaks into some of its basic colors as it does do. Blue is scattered efficiently while other colors are not scattered as effectively.
This idea destroys the idea that we are seeing the blue reflection of the ocean. There may be something to this original idea but the light-scattering concept is the basic reason we see blue when we look up.
Light of Many Colors
Sunlight is white. That’s the way it generally appears to the human eye. But if a prism or some other object can separate the basic parts of this white light we might see red, orange, yellow, green, blue and violet. Light travels in waves, with some waves shorter than others. For example, blue light waves are shorter. Red light waves are longer. Notice that these colors are at opposite ends of the color spectrum.
If white light scatters, bends or is reflected it may appear as some of the colors of this spectrum. Blue light portions of sunlight are scattered by the molecules of the different gases and moisture in the air. That’s why it looks blue the majority of the time.
Other Colors
At times we see the horizon in different colors. If a sunset appears deep red or orange it’s probably because of the moisture, dust and other particles hanging in the air. The white light of the sun is scattered differently at those times than during a clear day when the sky appears to be blue.
Some sunlight energy is absorbed by objects on the Earth or by the Earth itself. Some light is reflected back into the atmosphere. It all depends on what is in the air – dust, pollution, water vapor etc.