In case you were ever one of countless people who have ever wondered to themselves why the sky was blue, then your answer will hopefully be cleared up. It all begins with the simple and complicated physics of it all. To commence understanding, first you must know that whenever any kind of light comes into contact with some sort of boundary between two transparent pieces of material, with different indices of refraction, a portion of this original light is reflected. On the other hand, a portion of its original light is also transmitted due to refraction.
To further understand this concept, the picture above shows the line (indicating the boundary) and the two spaces on either side as the transparent material. It then shows the types of reflection, absorption, and the path of light throughout its journey.
You may be wondering what any of this has to do with the answer to why the sky is blue. The previous information shows how the light gets used, some of it reflected, some refracted, some absorbed, and so on. Technically, the sky is blue “simply” because of scattered sunlight. Although we may see the sky as blue, in reality it is more on the violet end of the spectrum but the human eye is not as sensitive to see this. (Patterns in Nature) Continuing to look at the color of the sky, some people might wonder why we see more towards the blue end of the spectrum rather than the red. The answer to this question is that the blue and violet wavelengths are much shorter than red scattering. The idea that the sky was blue because of gases in the atmosphere also was brought up by a scientist named Rayleigh. There have been several theories tested and thought up of by previous experimenters to explain the idea of why the sky was blue.
The scattering of light in an atmosphere is a very important aspect to look at when asking the infamous question of why the sky is blue. Before, the visible spectrum of red and blue was discussed in relation to the color in the sky.1/lambda to the fourth power is the formula used to equate to the scattering of light by molecules.This makes sense because the red end of the spectrum has longer wave lengths than the blue and violet end. If you were to plug a longer wavelength into the formula, you would notice that it would be a much larger number under one, meaning a smaller number as a whole. When a shorter wavelength is plugged in, a smaller more manageable number is created. The atmosphere has a lot to do with the scattering of light. When the sun is at his highest point, or around midday 12 o’clock, it has to pass through the thinnest layer or atmosphere that it has all day. This explains why the sky tends to be brightest and clearer than any other point in the day; and also why you get sunburned or tanned more (since the sun is passing through the thinnest layer of atmosphere.)
This picture and all of the above information after Patterns in Nature was used fromPolarization; and The Human Eye.Again, the wavelengths are a huge part in why we see the sky as blue. The longer wavelengths of the reds and oranges tend to pass straight through, without being changed. The blues and violets are some what tampered with because the shorter wavelengths are far easier to be absorbed. When they are absorbed, they are then radiated and scattered into all different directions. Since the blue light shows up in all directions, you see the whole sky as being blue as a whole, rather than separate parts. For a moment, picture yourself at a beach; when you look out at the clear refreshing blue sky, you notice further out on the horizon there is a paler blue and then almost whitish color. Although this may never have been a mind-boggling thing to you, some people have also pondered this question as much as why the sky was blue. Since the horizon is much farther away from you, there needs to be more blue light at stronger amounts of it to reach you so that you see the same color closer up. However, this is not the case so you see a much lighter version of the blue color you see straight above you. (Blue Sky http://www.sciencemadesimple.com/sky_blue.html)
All of this wavelength information can also be used to help determine why the sunset ends up being red. The longer wavelengths in the early morning and late at night help to explain why the colors red and orange are more apt to show up. The sun goes down and has to go through a thicker atmosphere and therefore the longer wavelengths tend to be way more prominent. The light also must go farther to get to your visible eye while the sun rises and sets because it is on the horizon, rather than right above you. As I said before with the paler and lighter blues on the horizon, the sunrise and sunset is also on the horizon, so the longer wavelengths will get to you easier than the shorter blues and violet wavelengths. That is why you see the reds, oranges, and pinks when the sun sets and rises
http://members.aol.com/danglick01/Sunset1.jpg
Rainbows:
First, to understand rainbows, you must know that white light contains all of the colors of the visible pattern, or as we all know it, “ROYGBIV”. We are able to see these colors lets say, through a prism, because each color has its own wavelength that directs how it bends away, towards, or in any direction. For example, blue light typically refracts because of its shorter wavelength where as green refracts, but less than blue and so on. So when light is shown through a glass prism and it hits at just the right angle, the colors are refracted and dispersed, or scattered about to create the visible spectrum. Also, to create another visual, if sunlight was shown into a glass of water, the light would refract and bend and create a spectrum on the floor where you would see a column of your visible colors. (http://acept.la.asu.edu/PiN/rdg/rainbow/rainbow.shtml#top)
The rainbow occurs because after raining, the droplets of water in the air act as their own tiny prisms, refracted and dispersing the wavelengths of light. As the sunlight goes into the water it reflects and disperses, and depending on the angle of refraction, shows a color in the rainbow. The colors vary due to the angle of refraction and the length of the wavelength. (http://www.howstuffworks.com/question41.htm)
http://inspirationalrainbows.com/images/desert_rainbow.jpgFor many centuries, there have been stories of mirages where people claim to see things that in reality aren’t there, no matter how convinced they are. These “mirages” are created by two layers of air at quite different temperatures. As discussed earlier, when there is a boundary between two transparent materials, light is refracted and reflected. Mirages occur because when the air is at the ground, but not quite touching it, and becomes overheated, an image occurs. I’m sure at one point or another you have been able to see the heat in the air on the ground on a hot summer’s day. There is almost like a ripple effect where it looks like the air is bending and takes on wave like characteristics. (
Lastly, although many may believe they are the mind playing tricks on people, that is actually false. They truly do occur due to the refraction of light in the atmosphere and the changes in air temperature combined with the light. (http://mintaka.sdsu.edu/GF/mirages/mirintro.html)
No comments:
Post a Comment