What makes rainbows form an arc?

Answer 1

The rainbow is formed by the refraction and reflection of the sun's rays as they fall on drops of rain which act as prism to produce the different colours.
The position of the sun,the rain drops and the observer count in producing the rainbow.The angle which the rain drop makes at the observer's eye is particularly important.
According to simple geometrical principles,the rain drops which lie at this angle and in a direction opposite to the sun, lie in the form of a full circle or part of it(arc).Even if there are enough raindrops to form a full circle,it will look like an arc as it is limited by the horizon.
If the observer is on a high mountain and the sun is near the horizon,he will be able to see the whole circle of rainbow.

Answer 2

Well its mostly formed when it rains and the sun comes out but to describe it: A rainbow is an arc of light separated into bands of color (parallel stripes) that appear when the Sun's rays are refracted and reflected by drops of mist or rain. The colors of the rainbow are red, orange, yellow, green, blue, indigo, and violet. These are the full spectrum of colors that make up the sun's white light. Thus, rainbow is a multicolored arc of light in sky. A clear cloudless day-time sky is blue because molecules in the air scatter blue light from the sun more than they scatter red light. When we look towards the sun at sunset, we see red and orange colors because the blue light has been scattered out and away from the line of sight.

Answer 3

The sun is round.

Answer 4

the water bends the light therefore it is round