hmm why is a rainbow always an arc?

Answer 1

Actually it's a circle, but you only see a part of the circle (unless you're in an airplane).

This happens because all raindrops are spherical, and therefore they all refract light at exactly the same angle from the Sun. Since the Sun is in just one point in the sky, the locus of that angle forms a circle on the celestial sphere. You see the part of the circle that is above the horizon -- that is, that part of the circle where there are a lot of raindrops in the sky.

Answer 2

Actually rainbow is a full circle.Our height is too small to look at the full circle and hence it is limited by the horizon and we see only a part of it(arc).The details are given below.
When we see the rainbow there is a particular angle at which the reflected rays from the rain drops reach our eye.According to simple geometric principles,the raindrops which lie at this particular angle and direction opposite to the sun lie in the form of full circle or a part of it(arc).Even if there are enough rain drops to form a full circle,to an observer on the earth,it will look like an arc as it is limited by the horizon.When the sun is near the horizon,an observer on a high mountain can see the whole circle of a rainbow.

Answer 3

Good question. A rainbow is defined as follows—Any one of a family of large, colored, circular (or nearly circular) arcs formed by light (usually sunlight) falling on a population of water drops such as provided by rain, cloud, fog, or spray.
The apparent center of the arcs is normally the shadow of the observer's head, so the rainbow is a personal phenomenon with each person seeing a slightly different bow. Although the rainbow can form a circle, when caused by rain the bottom part of the circle is usually cut off by the ground, leaving an arc, the extent of which depends upon the elevation of the light. The term rainbow is not applied to the small, nearly circular arcs seen around the sun and antisolar point in clouds. These are the corona and glory. Nor is the term applied to the large circular arcs formed by light falling on ice crystals. These are the halos. Rainbows are seen as related groups of arcs, such as the primary rainbow (with red on the outside, blue on the inside), the (larger) secondary rainbow (with red on the inside), the supernumerary rainbows (seen to the inside of the primary bow), and the reflection bows (the centers of which are above the horizon). However, the appearance of these bows can vary markedly depending upon whether they formed in rain, drizzle, or cloud, as both the radius and color purity of the arcs depend on drop size. Certainly, the brightest and most frequently seen of the bows is the primary rainbow, but whether the whole arc above the horizon is seen or not depends upon the location of the rain. It is not uncommon for someone to report seeing two rainbows, when these were merely two unconnected portions of the same bow. There is a hierarchy of theories of the rainbow with simplicity being purchased at the expense of verisimilitude. Theories that treat light as a series of rays do a good job of explaining the approximate positions and colors of the primary and secondary bows but fail to account for the supernumerary bows. To account for such easily observable features of the natural bow as the variations of color purity, brightness, and distribution of the supernumeraries around the arc, such things as the wave nature of light, the drop-size distribution in a cloud, and the size- dependent shape of raindrops must be taken into account.

Answer 4

It is actually a complete circle, but we only see half because the Earth gets in the way. The colors are caused by sunlight shining onto the droplets at an angle. It is probably a circle because the droplets are spherical, but I'm just making an educated guess.

Answer 5

the rainbow is shaped like it is because it is refracted light thru rain. the longer wavelengths are refracted differently than the next longest etc. therefor the paths of light are arranged in an arc from red to violet.

Answer 6

becuase rainboes were first made when the angels were sad,, and they cried making the world wet and dark,, and moths who used to be amazingly colorful and pretty decided to flutter there beautiful color into the sky. they asked the butterflies for help bu the butterflies were too vain, and wouldn't help. So all the moths fluttered all there color into the sky and flew as far as they could, but when there color started to wear out and they got tired they tended to slowly start drifting to the ground. At that time the moths were colorless,, but the sky became beautiful with their color and the angels became happy.
. .
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Answer 7

because that's the way they were created by the way the sun hits them ppl copied them and now they're a fad

Answer 8

They are actually a circle.

Answer 9

http://timesofindia.indiatimes.com/articleshow/2021393.cms