why is rainbow in that shape but not a straight line?
968711
A rainbow is curved due to angle requirements.  Light from the sun that\nbounces through a drop of water, comes into your eye, and appears red must\nbounce at a specific angle.  Join two sticks together at a set angle.  Place\none end at a dot to represent the sun.  Place the other toward your eye.\nThe place where the sticks join, where the water drop is, can be rotated\naround in a circle.  A rainbow is shaped like a circle.\nWell,\n\nYou never see the entire rainbow because of the horizon.  When you look at a\nrainbow, the Earth gets in the way of most of the circle.  The portion you\nsee is just the top portion.  Draw a circle and cover a little more than\nhalf of it.  What is left is the shape of a rainbow.\n\n____________________________________________________\nWhy does the light that is dispersed by the rainbow forms a bow? The answer involves the use of some simple geometry. The first point is that a rainbow is not a two-dimensional arc; it is in fact a three dimensional cone with the apex at the observer's eye. The reason that it appears to be only a two dimensional flat object isbecause there is no evidence of distance. All the drops, which disperse lighttowards the observer to form the rainbow, lie in the shape of a cone withmany different layers. The outside layers disperse the red component, thelayer below  that - the orange component, and the layer below that -the yellow component, etc. \nConsider the path of a ray of monochromatic light through a single spherical raindrop. Imagine how light is refracted as it enters the raindrop, then how it is reflected by the internal, curved, mirror-like surface of the raindrop, and finally how it is refracted as it emerges from the drop. If we then apply the results for a single raindrop to a whole collection in the sky, we can visualize the shape of the bow.\n\nAlso consider only the dispersion of the red component of the light. It has been shown previously that the red component is seen when the angle between the incident rays and dispersed rays make an angle of 42 degrees. Of course beams are dispersed at 42 degrees from drops all over the sky in all directions up, down, left, and right. However, only red light, which reached the observer eye, comes from the water drops which are on the cone with sideto axis angle of 42 degrees. If the observer's eye is at the apex of the coneas shown in Figure 3, then to see the violet part of the bow we would needto look at 40 degree to the conical axis. Therefore, the cone that producesthe violet component comes from a cone inside that of the cone which producedthe red part. The same argument can be made for all the other colors, andbecause different colors are formed by different cones, when they are viewedfrom the apex they appear in the form of a bow.\nIt is interesting to note that because only the drops on the cone with apex at the observer's eye are responsible for the formation of the rainbow, which an observers sees, then an important implication is that each person looking at a different rainbow. That leads to another interesting fact that both of the observer's eyes actually see a different rainbow, as they are both at the apex of different cones.
380553
When we draw a circle with a compass, we keep the angle between the two legs constant.\n\nA ray from the top most point on the rainbow to our eye makes an angle to the horizontal direction. Theory says this angle is a constant.\n\nImagine the ray as one leg of long compass and the horizontal direction as another leg which points the center. Keeping the angle constant when the compass is rotated an arc is formed. \n\nIf we go high up we can see the whole circle.
1018600
no. rainbows are actually circular, and therefore have no end or beginning. they seem to end at the horizon, but actually continue on the other side. i know it sounds weird, but if you see them from above, in an airplane, you can see the whole circle.
773813
Rainbows don't exist.  What you can see is the light from the sun (behind you) relected and refracted by raindrops.  You can't go there - what you see would move with you.\n\nYou can only see a rainbow where there are raindrops.  It seems to end where it touches the ground, but that's because there aren't any raindrops down there.  If you could get high enough, you would be able to see the whole circle - so there's no end.
73801
When white light (all colors) hits a rain drop, each color refracts at a different angle.  The color is governed by what frequency it is.  Red has the lowest frequency and violet has the highest.  This is what causes the specific pattern of the rainbow.  The angle is with respect to your eye.  Hope this helped.
1103987
Rainbows are 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, reflects off the back of the drop, and is 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 (color) 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 spectra crosses itself, and thus the red light appears higher in the sky, and forms the outer color of the rainbow.\n\nA rainbow 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. Its position is always in the opposite direction of the sun with respect to the observer, and the interior is actually a magnified image of the sun, which can be seen to be 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 (this means that if the sun is higher than 42° 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).\n\nSometimes, a second, dimmer rainbow is seen outside the primary bow, caused by a double reflection of the sunlight inside the raindrops, and appears at an angle of 50°–53°. Because of the extra reflection, the colours of the bow are inverted compared to the primary bow, with blue on the outside and red on the inside. (The full sequence of colors is red, orange, yellow, green, cyan, blue and violet.)\n\nA triple rainbow is even more rarely seen. A few observers have reported seeing quadruple rainbows in which a dim outermost arc had a rippling and pulsating appearance.
962965
Here's what happens: imagine you're standing with the Sun at your back looking at a water drop. As a light ray from the Sun hits the drop, it is bent inwards, toward the center of the drop. It bounces off the back of the drop (coming towards you again) and then refracts again on its way out. As a result you see the light ray appearing to come from some point behind the drop, that is, on the opposite side of the sky from the sun (which is where you see rainbows!) \n\n\nBut what about the colors? It turns out that each color of light is bent a little bit differently - red light is bent the least and violet the most. So, each color appears to be coming from a slightly different place behind the water drop. \n\nThe rainbow is circular because only drops located at certain places on the sky (in a circle around the point opposite the Sun) redirect the light exactly back toward your eye. It's only the light from those drops that you see, and hence you see a circle.\n\nanother explaination: This is difficult to envision and to describe, but we'll use some real common sense objects for our model. Picture yourslf standing in front of a tunnel, like you might find under a bridge - a nice even, round, smooth tunnel. Now, if you cast a shadow parallel to the ground, like a shadow from a power line (not the pole, the line - which is parallel to the ground) and let the shadow fall inside the tunnel, you can imagine that the shape of the shadow on the ceiling of the curved tunnel looks as though it is arced, even though the source of the shadow is a straight line. Can you picture that? This is what is happening in the atmosphere. The rainbow is actually a straight line, since light travels in a straight line. Its just that the straight line is falling across a 'fish bowl' like pocket of moist, reflective air, like our tunnel in the model. The rainbow appears, therefore, to be an arc.
429250
I think it is something that placed in a way that from \nright to left (flat way) or so but not from up to down or down to up.\nexample: ------------------------- horizontal line
655753
I'll try to explain here, but it would be a lot easier if I could draw you a picture.  Here goes... \n\nThe shape of the rainbow actually has to do merely with your own perspective.  Each droplet of water acts like a prism, deflecting different colors of light at slightly different angles.  All the rays of sunlight are more or less parallel when they enter air full of water droplets.  So each color is, on average, deflected a certain number of degrees, varying by wavelength.  But you can only see the colors if they were deflected towards you.  So if, say, green light is deflected by 10 degrees on average, then most of the green light that you see is coming from areas where your line of sight is 10 degrees off from the direction of the sun's rays.  Geometrically speaking, the source of the light has a cone shape, but from your perspective (at the "point" of the cone) it looks like a circle.  If you have ever seen a rainbow while in an airplane or up on a mountian, you will notice that it is actually a full circle.  Usually, we can only see the top half, because the ground absorbs the light instead of deflecting it, and because the "cone" of light is far away (thus its radius is very large, and the bottom part goes "into the ground").  However, you can sometimes see circular rainbows in the mist from a waterfall or sprinkler - anytime you are high up or the water source is very close.\n\nAargh, this would be so much easier to explain with a pencil and paper... Oh well, hope it was useful anyway.
203928
Rainbows are made from light reflecting off the small droplets of water in the air, usually after it just rained so it doesn't really travel any differently...
771669
Cause squares would look weird
246417
Because the physics are: the sun at a 42 degree angle, behind you, and the fact the watger droplets in the air make the rainbow, and the world and consequently the air is curved.
942352
A rainbow is an optical and meteorological phenomenon that causes a nearly continuous spectrum of light to appear in the sky when the Sun shines onto droplets of moisture in the Earth's atmosphere. It takes the form of a multicoloured arc, with red on the outside and violet on the inside. A double rainbow includes a second, fainter, arc with colors in the opposite order.\n\nEven though a rainbow spans a continuous spectrum of colours, traditionally the full sequence of colours is most commonly cited as red, orange, yellow, green, blue, indigo and violet. It is commonly thought that indigo was included due to the different religious connotations of the numbers six and seven at the time of Isaac Newton's work on light, despite its lack of scientific significance and the poor ability of humans to distinguish colours in the blue portion of the visual spectrum.\n\nScientific explanation\n\nThe 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.\n\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 most often perceived to be white.\nRainbows may also appear in the spray of a water fountain\nEnlarge\nRainbows may also appear in the spray of a water fountain\n\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°. This angle is independent of the size of the drop, but does depend on its refractive index. As seawater has a higher refractive index than rain water, the radius of a 'rain'bow in a sea spray is smaller than a true rainbow. This is visible to the naked eye by a misalignment of these bows [1].\n\nSince the water 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\nA 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 obser
216785
The rainbow represents the diversity in our culture. and freedom from persecution.  it came about after Stonewall (that is a mile marker in our struggle to gain visibility in our society).  we also have a more ominous symbol. that is the pink triangle that represents our turmoil from the Germans along with the Jews the wore the star of David
1173045
You know how you see a rainbow when its really humid, or when it rains and there is sun? Thats what you saw, you saw a rainbow, but not a half rainbow, but rather a whole rainbow around the sun. A ring rainbow, this is due because of the high humidity that is in the air, its the same as a rainbow, just around the sun.
507580
A rainbow is an optical and meteorological phenomenon that causes a nearly continuous spectrum of light to appear in the sky when the Sun shines onto droplets of moisture in the Earth's atmosphere. It takes the form of a multicoloured arc, with red on the outside and violet on the inside. Even though a rainbow spans a continuous spectrum of colours, traditionally the full sequence of colours is most commonly cited as red, orange, yellow, green, blue, indigo, and violet. It is commonly thought that indigo was included due to the different religious connotations of the numbers six and seven at the time of Isaac Newton's work on light, despite its lack of scientific significance and the poor ability of humans to distinguish colours in the blue portion of the visual spectrum.\n\n\nThe 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.\n\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.\n\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\nA 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 vie
129313
The curvature of the rainbow is a consequence of having only those raindrops that are at the vertices of 42 degree angles between you and the sun. The collection of all these raindrops is of course an arc. \n\nThe light enters the raindrop from behind you, and bounces off its back surface. The colors separate, because each color has a different speed in the water, and therefore refract a different amount.