Physics Explained

By Alex Eberts
Many people have a lot of unanswered questions regarding some of the things that we as humans see on a daily basis. Why do rainbows occur? How are mirages visible? Why is the sky blue? How come there are so many colors in a sunset? All of these questions can be answered using physics. Physics can explain many of the natural phenomenon’s we see everyday.


Glass can create different effects using visible light and the spectrum of colors. The effect glass creates when light is refracted is called dispersion. Dispersion occurs when the different colors, like blue and red, refract or bend in the glass in different ways. One specific device that has this effect is a prism; it breaks up the white light into all of the different colors. Raindrops act as prisms because if the sun is shining while it is raining then the light from the sun will refract or be dispersed off the raindrop. The white light hits the raindrop and when it is dispersed it is separated into different colors. This creates the effect of the rainbow and this is how we see rainbows. The diagram below demonstrates a raindrop acting as a prism with the white light from the sun being dispersed and refracted off it.











The raindrop acts like mirror also because it some of the dispersed light back at the sun. The different colors in the white light enter the raindrop at different angles therefore creating the different colors. Each raindrop only helps to contribute to one beam of light that is seen in the rainbow. Raindrops that are found located higher in the sky are red, orange or yellow light and raindrops that are found located lower in the sky are green, blue and violet. The antisolar line helps us to determine the color we will see. If a raindrop is located at 42° of the antisolar line then we will see red light. This helps to create the rainbow as a whole and make it so large. If the raindrop is located at 40° at the antisolar line then we will see blue light etc. The diagram below helps to explain how we see things due to the antisolar line. (Physics of Rainbows)











Why is the sky blue? Light in the sky is considered to be scattered light. This means that it is made up of many particles that when light is refracted or dispersed off of them it creates the blue sky that we see everyday. However, the sky is not only made up of blue light, it is made up of all the colors of the spectrum our eyes just mainly see blue. The image of clouds in the sky is created a fairly similar way. The reason why our eyes see white clouds is because it is light bouncing of water particles in the air. Therefore the clouds may look white and opaque, but they are really transparent.(Physics of the Blue Sky)

Sunsets and sunrises have the effect of being very colorful because of light scattering off of molecules located in the atmosphere. The spectrum of the color blue is much more readily visible to the human eye therefore that is why when we look at the sky we mainly see the color blue. At sunrise and sunset the light from the sun has a harder time getting through the atmosphere to our eyes therefore light is scattered towards the red end of the spectrum.(Why the Sky is Blue)

Mirages are another effect that can be explained due to physics. Mirages happen when there are two different temperature layers in the air. There is a hot layer of air and a cold layer of air. Because there are two layers there is a boundary between them which can refract light it creates an image. An example of when this can occur is on asphalt in the summer time.(Mirages1)

Works Cited

http://acept.la.asu.edu/PiN/rdg/rainbow/rainbow.shtml#top

http://acept.la.asu.edu/PiN/rdg/sky/sky.shtml

http://physics.bu.edu/~duffy/PY106/Eye.html

http://www.unmuseum.mus.pa.us/mirage.htm

Winter Break Blog: Rianbows, Mirages, Color of Sky

Physics Explained

Rainbows:

White light is a combination of many colors; a rainbow is when the white light has all of its colors separated. To form a rainbow the white light from the sun hits the raindrops and then reflects off the side of the raindrops and exits into your eyes. Each angle has a different distinct color.

Color of Sky:

The sky is scattered sunlight whose particles are smaller than the wavelength of the light. The sky is actually not only blue, it has many other colors in it as well; just the eye are the most sensitive to blue and not so much violet, and most of the light in the sky is violet and blue, therefore, creating the blue image in the sky. A further explanation as to why the sky is the color blue is because of the preferential scattering of short wavelength blue light compared to the scatter of long wavelength of red light, which is proportional with the gases in the atmosphere to the scattering of light by individual molecules (Rayleigh scattering).

Mirages:



The effect that two air levels at different temperatures is a mirage. Light can be refracted; considering there are two different temperatures of air and cold air is denser than hot air is. The specific type of mirage known as the oasis mirage happens when the air just about the ground is heated by the ground. A real example of this is when you believe to see the asphalt ground as water. This appears like this because the black color of the asphalt heats up the above air fast, which creates the refraction of the light from the sky. Light is refracted many times if there are numerous amounts of layers of different temperature air. As a result to this, natural objects can appear to look like city buildings. An example of this type of mirage is the Alaskan City Mirage.

Works Cited

"Light and Optics." Patterns in Nature 2000 March 3, 2008 http://acept.la.asu.edu/PiN/rdg/rainbow/rainbow.shtml#top.

"What Causes a Rainbow?." 2000 March 3, 2008 http://www.howstuffworks.com/question41.htm.

"Blue Skys and White Clouds." Patterns in Nature 1999 March 3, 2008 http://acept.la.asu.edu/PiN/rdg/sky/sky.shtml.

"Mirages in The Sky." 1998 March 3, 2008 .

Physics Blog: Winter Break

Rainbows, Mirages, Sky

Rainbows, Mirages, and the color of sky at dawn and dusk are more than just a pretty site for one’s eye. They have a lot of physics behind them that can explain their nature and being. The leprechaun does not just find the pot of gold at the end of a rainbow, but can be enlightened by the physics that causes such a miracle. The refraction of various lights causes the colors that encompass our world. Many physics concepts such as dispersion, refraction, and others involve the explanation of the formation of rainbows, mirages, and the sky.
The topic of rainbows is very interesting, because the concepts involved are quite complex. Think about the time one sees rainbows; it is always after a rainstorm, light rain, or some type of precipitation. This is one of the factors that help form the rainbows. The sunlight that forms rainbows bounces off the water vapor and particles in the air and reflect back into your eyesight. The white light from the sun is not only reflecting off the water, but it is also refracting and dispersing from the drops. Only the refracted rays are actually seen in the eyes, because they form the colors and rainbow. Specifically, every raindrop shows one color of the rainbow. For example, every light reflected at 42 degrees is seen as red light. The various colors that make up a rainbow spectrum; red, orange, yellow, green, blue, indigo, violet, each have specific and different refractions. For example, blue light bends or refracts more so than the green light. The green light then refracts more than the red light, and so on. The prism that makes up the rainbow split into different colors, which form due to the refraction techniques. “Each rainbow is your own,” this is because each rainbow looks different compared to the rainbow seen from a friend’s companion (Rainbows: Lights and Optics).
Another physics phenomenon includes the mirages in a sky. Two layers of air at different temperatures form a mirage. Cold air is denser than hot air, therefore the boundary between the two layers can refract light. The easiest and most commonly known mirage is the pond of water in the desert. Examples of various mirages include a band of marching soldiers on a mountain, certain UFO spottings, and of course the water in the desert. Mirages on top of water are seen when the air temperature is much warmer than that of the water. When there are several boundaries between the air layers, the more light is refracted and the more complex the image appears. Some claim to have seen castles, cities, and buildings refracting off a cliff. There are many mirages seen in the desert as well as the Arctic especially. The smoothness, shape, and amount of boundaries all are factors of what make the mirage (Krystek).
Mirages are not in fact optical illusions but real physics phenomenon, and can be photographed. This chart explains the classification of a mirage: IMAGEEEEE? The refraction of a mirage includes terrestrial refraction, inside the atmosphere and astronomical refraction, beyond the atmosphere (Young). The various forms of refraction and the boundaries between airs form the physics marvel of a mirage.
Lastly, the final physics wonder seen throughout the atmosphere is why the sunset and sunrise are full of colors. The sun formulates this because of the way the optics of the human eye work. When the sun is rising or setting, it has to travel through much more atmosphere to reach the human eye. Most of the blue light scatters in other direction, leaving mostly the red and orange side of the spectrum to reach our eyes. The human eye relies on refraction and lens to see the images of the world. Because the red and blue lights are on the opposite side of the light spectrum, they come to they eye at different times. Due to the refraction of our eye, blue light is almost never seen, because it refracts in too many different directions. The red, orange, and yellow light is more direct and can be seen from far away at sunrise or sunset (Polarization).
Physics is a science full of interesting and incredible marvels. The science of rainbows includes dispersion, refraction, and reflecting. Mirages are all about boundaries between airs that create a real photographable image. Finally, the sun, the thing that lights the world is perceived through our eye due to the different wavelengths of color. Overall, each one of these topics includes a lot of interesting physics that make up their formation.










Works Cited
Krystek, Lee. "Mirages in the Sky." Mirages in the Sky. 1998. 1 Mar 2008 .
"Light and Optics." Patterns in Nature. 26 Dec 1999. Department of Physics and Astronomy: Arizona State University. 1 Mar 2008 .
"Polarization." Polarization; And the Human Eye. 1999. 4 Aug 1999 .
Young, Andrew T. "Introduction." An Introduction to Mirages. 2008. .

Human Eye Paper

The eye is a very interesting and complex organ within the human body. Its main function is to provide sight.

The outermost layer of the eye is called the sclera and it maintains the shape of the eye. The front clear part of this is called the cornea. Extraocular muscles are the muscles that move the eye and these are attached to the sclera. All light must pass through the cornea first and then moves onto the choroid which is the second layer of the eye. This part contains blood vessels that supply blood to the different parts of the eye and contains two structures called the iris and ciliary body. Within the iris there are two muscles the sphincter and dilator. The dilator muscle makes the iris smaller and pupil larger which allows more light into the eye. The sphincter muscle makes the iris larger and pupil smaller which allows less light into the eye. Pupil size can change from 2 millimeters to 8 millimeters on average and when the size of the pupil changes, it changes the amount of light that enters the eye 30 times. The innermost layer of the eye is called the retina and this is the light-sensing portion of the eye. Contained in this layer are rod cells, which are responsible for vision in low light, and cone cells that are responsible for color vision and detail. The macula is located in the back part of the eye in the center of the retina. In the center of the macula is the fovea centralis and this part contains only cones as it is used for seeing fine details. The retina also contains a chemical called rhodopsin, known as "visual purple." This chemical converts light into electrical impulses that the brain then measures as vision. Retinal nerve fibers are connected at the back of the eye, forming the optic nerve, which sends the electrical impulses to the brain. The optic disk is where the optic nerve and blood vessels exit the retina. This is a blind spot on the retina because there are no rods or cones. Yet we are unaware of this blind spot because each eye covers the blind spot of the other eye. This is some of the basic anatomy of the human eye. (Bianco, M.D. 2)

There are many infections, diseases, etc. that cause vision problems or even blindness. Glaucoma is when drainage of an aqueous humor which is produced in the ciliary body and then drained through the canal of schlemm is blocked. The conjunctiva, which keeps the eye moist, can have an infection called conjunctivitis also known as pink eye. The eye is protected from injuries by a bony cavity called the orbital cavity and eyelids do this by blinking. Eyelashes and eyebrows also protect the eye from particles that may harm it. Nearsightedness, also known as myopia, is when a person is able to see near objects well but has difficulty seeing objects that are farther away. Farsightedness, also known as hyperopia, is when a person is able to see distant objects well but has difficulty seeing objects that are closer. Astigmatism is an uneven curvature of the cornea that causes distortion in vision. The older we get the more the lens becomes less elastic and loses its ability to change shape. This is called presbyopia. It is more noticeable when we try to see things up close, because the ciliary body must contract to make the lens thicker and the loss of elasticity prevents the lens from becoming thicker. This causes us to lose our ability to focus on certain objects. A cataract is cloudiness in the lens that blocks light from reaching the retina and can be corrected with surgery. Trachoma is an infection caused by an organism called Chlamydia trachomatis and is disease is the most common cause of blindness is the world, however is rare in the United States. Other causes for blindness include vitamin A deficiency, tumors, strokes, neurological diseases, other infections, and hereditary diseases. (Bianco, M.D. 9, 10, 12)

The eye relies on refraction in order to focus on various objects. Refraction takes place by the aqueous humor, which is a liquid on top of the lens. Light is refracted as it comes into the eye by the liquid, is then refracted more by the lens, and then more by the vitreous humor, which is a jelly-like substance located in the space between the lens and the retina. The lens is critical in creating a sharp image so it can adjust quickly when focusing objects at different distances and this process is known as accommodation. (Polarization 1)

The eye is a very interesting and vital organ in the human body. It works to help us focus in on images at various distances. By this we are able to observe the world around us and enjoy its beauty.

Works Cited

Bianco, M.D., Carl. ""How Vision Works"." How Stuff Works. 1998. 2 Mar 2008 http://health.howstuffworks.com/eye4.htm

unknown, unknown. "Polarization; and the Human Eye." University. 2 Mar 2008 http://physics.bu.edu/~duffy/PY106/Eye.html