Why does a rainbow appear as arch?
483599
the other answers are somewhat correct but unnecessarily long....\n\n1. the rainbow is actually a circle that is partially visible as an arch due     \n    horizon limitations.\n\n2.  it is a circle because the light source ( the sun ) is a circle.
211510
This site might help "see" what is going on and why.  Interesting question by the way.  I saw my first one last summer and the colors were so bright.  It was amazing!  Had everyone out in the parking lot of the strip mall checking it out.\n\n\nhttp://hyperphysics.phy-astr.gsu.edu/Hbase/atmos/rbowpri.html\n\nhttp://en.wikipedia.org/wiki/Rainbow
1107176
a rainbow? stuffed if i know....lol
557311
hmmmm, my bubles have all the colors of the rainbow.\njust need to look closely. a beauty, those colors are slowly flowing over the surface of the bubble, ....then i pop the bubble, muahahahaha.
122346
Why don't you search the answers to the previously posted questions here on this topic? This has been asked over and over. \n\nHere is a little bit to get you started:\n\nRainbows are caused because the different colors in white light are bent by different amounts in rain drops, so the colors get separated. The sun shines from behind the observer, and then bounces off the back surface of the raindrops, and those raindrops that are at the required position for light to reach the observer from the sun contribute to the rainbow. This arc is formed by the collection of raindrops which are at the vertices of angles of 42 degrees between the observer and the sun.
855168
Yes---the rainbow is a reminder of God's promise to us that never again will the whole earth be covered in water as it was in Noah's time.\nGENESIS 9:12-16--"And God said, This is the token of the covenant which I make between me and you and every living creature that is with you, for perpetual generations: I do set my bow in the cloud, and it shall be for a token of a covenant between me and the earth. And it shall come to pass, when I bring a cloud over the earth, that the bow shall be seen in the cloud, and I will remember my covenant, which is between me and you and every living creature of all flesh; and the waters shall no more become a flood to destroy all flesh. And the bow shall be in the cloud; and I will look upon it, that I may remember the everlasting covenant between God and every living creature of all flesh that is upon the earth."\nWhen we see a beautiful rainbow in the sky, may we see not only it's beauty, but remember what it represents--a promise from our Creator.
985228
You can see a rainbow when the light is behind you.  It's reflected by the raindrops.  Light of a particular colour is refected by the raindrops that are at the correct angle between the straight line from the sun to the raindrop and the straight line from the raindrop to your eye.  The raindrops at that angle are in a circle, although of course there aren't any under the ground so you only see an arc.  If you're in a plane and the sun and a raincloud are in the right places, sometimes it's possible to see the whole circle.
265331
The only reason color exists is because objects (rain drops in this case) reflect certain wavelengths and obsorb certain wavelengths of light.  The only reason we see the colors in the rainbows is because the sun produces white light which, when refracted, will produce ALL OF THE POSSIBLE COLORS.  This is interesting, you will notice there is no brown in the spectrum (or rainbow); therefore, brown is not a color.  The sun doesn't have the same color as the rainbow, the rainbow has the same color as the sun.
238996
There is no gold at the end of a rainbow.\n\n\nThe traditional description of the rainbow is that it is made up of seven colors - red, orange, yellow, green, blue, indigo, and violet. Actually, the rainbow is a whole continuum of colors from red to violet and even beyond the colors that the eye can see.\nThe colors of the rainbow arise from two basic facts:\n\nSunlight is made up of the whole range of colors that the eye can detect. The range of sunlight colors, when combined, looks white to the eye. This property of sunlight was first demonstrated by Sir Isaac Newton in 1666.\nLight of different colors is refracted by different amounts when it passes from one medium (air, for example) into another (water or glass, for example).\nDescartes and Willebrord Snell had determined how a ray of light is bent, or refracted, as it traverses regions of different densities, such as air and water. When the light paths through a raindrop are traced for red and blue light, one finds that the angle of deviation is different for the two colors because blue light is bent or refracted more than is the red
1145967
The arc of a rainbow has nothing to do with the curvature of the earth.\n\nA rainbow is formed because light from the sun is double refracted back toward you. When you see a rainbow the sun will be behind you, and the centre of the rainbow will be opposite the position of the sun.\n\nOf course, the light is scattered back equally in every direction you look, so a rainbow is actually a full circle with its centre opposite the sun.\n\nHowever, unless you are in a plane looking down (when you do see a full circle - i've seen it) the point opposite the sun will be below the horizon, so part of the circle will be cut off by the horizon and you will see an arc.
77085
Because it is refracting light that is coming from all around. When you see a rainbow produced by a prism it looks straight but if you were able to enlarge it enough it would be round.
270700
much to many people's belief's 7 basic colors aren't based on the rainbow colors. in fact some of the colors on the rainbow is actually a mix of primary colors that are really secondary or tetiary. not primary [basic]. so... here we go...\n\n\n7 basic colors are:\n\n1- a cool yellow a.k.a Hansa Yellow Medium—a lemony, slight bias to blue-green;\n\n2- a warm yellow a.k.a New Gamboge— a golden, slight bias to red-orange;\n\n3- a cool blue a.k.a Phthalo Blue (GS)—an icy, slight bias to blue-green;\n\n4- a warm blue a.k.a French Ultramarine— a purplish blue, slight bias to violet;\n\n5-  a cool red a.k.a Quinacridone Rose—a rosy, slight bias to red-violet;\n\n6- a warm red a.k.a Pyrrol Orange—a tomatoey red, slight bias to red-orange;\n\nok..only six [6] are listed here. to get the 7th color,all u need to do is... well here's where the magic is....\n\na] Use a warm and a cool of each primary hue (a warm red and a cool red; a warm yellow and a cool yellow; a warm blue and a cool blue) to mix bright, high-inten sity secondary called a Mixed Primary Hue. The secret is in using the right split primary colors and not crossing over the lines into another section!\n\n++TIPS++\n\nTo mix the oranges, mix the red and yellow within the lines to the left of the circle. First mix orange, and then add more yellow for yellow-or ange and more red for red-orange. \nTo mix the greens, mix the blue and yellow within the lines to the right of the circle. First mix green, and then add more yellow for yellow-green and more blue for blue-green. \nTo mix the purples or violets, mix the pink or rose with the blue within the lines at the bottom of the circle. First mix purple , and then add more blue for blue-violet and red for red-violet. \n\nNow here's the rule that makes this work: 'When mixing two colors on the wheel to achieve high- intensity color, don't cross over the line-stay in each section. Just imagine, no more muddy colors!\n\nCrossing over the lines and mixing the colors on either side of the line causes the mixtures to become less intense and slightly grayer. Cross two lines and even more graying occurs. This graying is called neutralizing. It is the result of a slight touch of that third color being added to the mix. To mix earth colors, you simply cross over the lines or add a warm neutral to your mixtures.\n\nOK ...\n\nNow for the much awaited 7th basic color....\n\nThat's where Quinacridone Burnt Orange—the seventh color of our essential 7 basics-enters the scene… it's a versatile warm neutral.\n\n\nhehe. quite interesting. hmm. [^_^]
771669
Cause squares would look weird
321325
On top of the arch...???
202794
The 'end' of the rainbow is defined as:\nThe point of the rainbow that satisfies both of the following criteria:\n1 - point where the rainbow intersects the ground\n2 - point where is located in close vicinity one (1) pot of gold (any size pot of gold will do)\n\nIf only the first criteria is satisfied, you have found the 'beginning' of the rainbow.
379722
The rainbow effect can be observed whenever there are water drops in the air and sunlight shining from behind the observer at a low altitude or angle. The most spectacular rainbow displays when half of the sky is still dark with draining clouds and the observer is at a spot with clear sky overhead. The rainbow effect is also commonly seen near waterfalls or fountains. Rainbow fringes can sometimes be seen at the edges of backlit clouds and as vertical bands in distant rain or virga. The effect can also be artificially created by dispersing water droplets into the air during a sunny day.\nIn a very few cases, a moonbow, or night-time rainbow, can be seen on strongly moonlit nights. As human visual perception for colour in low light is poor, moonbows are perceived to be white.\nThe rainbow's appearance is caused by dispersion of sunlight as it is refracted by (approximately spherical) raindrops. The light is first refracted as it enters the surface of the raindrop, reflected off the back of the drop, and again refracted as it leaves the drop. The overall effect is that the incoming light is reflected back over a wide range of angles, with the most intense light at an angle of about 40°–42°, regardless of the size of the drop. Since the water of the raindrops is dispersive, the amount that the sunlight is bent depends upon the wavelength, and hence colour, of the light's constituent parts. Blue light is refracted at a greater angle than red light, but because the area of the back of the droplet has a focal point inside the droplet, the spectrum crosses itself, and therefore the red light appears higher in the sky, and forms the outer colour of the rainbow. Contrary to popular belief, the light at the back of the raindrop does not undergo total internal reflection; however, light that emerges from the back of the raindrop does not create a rainbow between the observer and the Sun. The spectra emitted from the back of the raindrop do not have a maximum of intensity, as the other visible rainbows do, and thus the colours blend together and do not form a rainbow.\n rainbow does not actually exist at a location in the sky, but rather is an optical phenomenon whose apparent position depends on the observer's location. All raindrops refract and reflect the sunlight in the same way, but only the light from some raindrops reaches the observer's eye. These raindrops are perceived to constitute the rainbow by that observer. The position of a rainbow in the sky is always in the opposite direction of the Sun with respect to the observer, and the interior is always slightly brighter than the exterior. The bow is centred on the shadow of the observer's head, or more exactly at the antisolar point (which is below the horizon during the daytime), appearing at an angle of approximately 40°–42° to the line between the observer's head and its shadow. As a result, if the Sun is higher than 42°, then the rainbow is below the horizon and cannot be seen unless the observer is at the top of a mountain or a similar vantage point. Similarly, it is difficult to photograph the complete arc of a rainbow, which would require an angle of view of 84°. For a 35 mm camera, a lens with a focal length of 19 mm or less would be required, whilst most photographers are only likely to have a 28 mm wide-angle lens.\nFrom an aeroplane, one has the opportunity to see the whole circle of the rainbow, with the plane's shadow in the centre. This phenomenon can be confused with the glory, but a glory is usually much smaller, covering only 5°–20°, as opposed to over 80° for a full circle rainbow.
1169657
there's a rainbow always after the rain