why does a rainbow arch towards the earth?
352181
I'm thinking it is all about the curve of the earths surface and therefore the curving atmosphere.
157694
Your perspective to the event, it is so large and you can only stand in on place at a time.  Hence why you can never find the end of the rainbow.
873831
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.
1034783
'False' rainbow or secondary one forms because of TOTAL INTERNAL REFLECTION through the optical medium (which probably is the rain drops). Total internal reflection can be understood like this: sine of angle of refraction equals sine of angle of incidence into the refractive index. So, when u kep on increasing the angle of incidence, the angle of refratction also keeps on increasing till when a point comes when it esceeds 90 degrees, i.e., when the refracted ray moves back out of the refracting surface (apparently reflected), and one gets an inverted image, hence the sequence opposite of VIBGYOR. Bye. Hope this helps.
524651
Cloud Rainbow, same thing, the light passes thru the moisture, you get a rainbow. I love them no matter how scientific I can get abut it.
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.
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...
43821
When light and water meet in the sky on a summer's day, for a few moments, a rainbow will appear. Such a beautiful sight! This phenomena of the atmosphere appears during or immediately following local showers, when the sun is shining and the air contains raindrops. A rainbow can best be seen with polarized sunglasses. We cannot follow the arc of a rainbow down below the horizon, because we cannot see those droplets in the air below the horizon. But the higher we are above the ground, the more of the rainbow circle we would see. That is why, from an airplane in flight, a rainbow will appear as a complete circle with the shadow of the aitplane in the center.\n\nThe bow is divided into bands displaying the different colors of the spectrum and is formed by the refraction and reflection of the sun's rays in drops of rain. Reflection is simply the return of light waves from the raindrop's surface. Light which appears to be white, is really made up of a mixture of red, orange, yellow, green, blue, and violet light
125458
Well I think they appear as lines; fat, multicolored, curved lines.  But they aren't really "there" where we see them.  That is, other people, say a mile away from you, will see the rainbow shifted from where you see it, and that's because the rainbow's apparent direction is relative to the sun's rays that are near you.  But is this the answer to your question?  Are you asking why they're not thin? straight?  Give us something, Bea.
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.
733617
it is due to the rotaion of the Earth with respect to Sun , \n\nit is visible from east first  not rising , \n\nthe light rays emerges form east.
427036
Rainbows are caused by sunlight reflecting off and refracting through raindrops. There is a very specific angle that each different wavelength of light will take so all parts of the rainbow of that color are always seen at exactly that angle away from the Sun, about 42 degrees for visible light. In math, the collection of all points at a certain distance from a point is a circle, so rainbows are seen as a circle around the sun.
1001101
A rainbow is actually round. On the ground, the bottom part is hidden, but in the sky, like from the view of a flying airplane, it can be seen as a round shape.
271966
It is a division of light into the color spectrum as it passes through water droplets, and it's also a reflection.\n\nAnd the source of the light to the droplets to your eyes is at an angle of 42 degrees relative.  If you were standing on the edge of a cliff, and the sun was behind you, you would see a circular rainbow.\n\nThe shape of the rainbow has to do with the shape of the water droplet.
811234
Because the Earth is round, the widest point could be from top to bottom.... it all depends on which way you are looking at it.
388125
A rainbow occurs when sunlight passes through sheets of falling rain which act as a prism to separate the light into it's full spectrum of colors. A double rainbow occurs when there are multiple sheets of rain that are perhaps angled slightly differently. One sheet of rain bends the light into one rainbow, the other sheet of rain bends the light in a slightly different path to create a second prismatic display. \n\nBasically, it is like haveing one light source (the sun) and two separate prisms set next to each other, but at slightly different angle giving you two separate spectra or rainbows.\n\nDouble rainbows are very cool indeed. I saw one last summer!
311578
It IS the amount of atmosphere, but primarily because of the refraction it causes.\n\nThink of it as looking through a rainbow from the side.  As light travels through dense layers of air, it bends, and the different colors in white light emerge.