What causes the curveature of a rainbow? The roundness of the earth, the sun or something else?

Answer 1

A rainbow is not substantively anything more then a prism of colors viewed through a humid like environment. (Water acts as a lens...think about the telescope in the movie "bugs life") Note that the rainbow moves as you move around it. (dependent upon the location of the sun, or the light source, you may see the rainbow or not. The rainbow is a reflection of light on the opposite side of water. raindrops also bend, or refract, light, like a lens. The reflection is spread into a cone of light. The edge of this cone is bright, because sunlight is concentrated at this angle.

Answer 2

Sometimes it's one or the other. Good question.
I'll give you an example:
The one that shines through something is due to the roundness of the sun. Cirrus clouds and rain falling.
I once saw something that scared the hell out of me. It was very cold and still dark (twilight) the cirrus clouds covered the sky and then a bright rainbow started at the horizon and went at a fast rate to the other side of the sky. It was a rainbow made by the ice crystals reflecting the rising sun. The sun was below the clouds. It was a bow because of the curvature of the clouds from left to right. It was awesome! I almost crapped my pants.

Answer 3

When a light ray impacts a water droplet it may be refracted and then be reflected a number of times off the inside of the droplet before being refracted on its exit from the water droplet. What happens to a particular ray depends upon where it impacts the droplet with respect to the center of the droplet. If the ray is dead-on-center it could be reflected back out of the droplet in a direction exactly opposite to the direction from which it entered. But generally the ray will be a bit off center and will be reflected backwards with its direction changed by an angle ρ, called the refraction angle.

A narrow bundle of rays impacting a particular water droplet will generate a cone of light with the cone angle being equal to the refaction angle ρ. In a vertical cross section of the cone some rays are refracted and reflected backward and downward and some are refracted and reflected backward and upward.

Observers on the ground experience only the rays that are refracted downward, but from an elevated observation point such as in an airplane the rays refracted upwards from rain droplets also enter into the formation of the rainbow. From an aircraft one can see such full circle rainbows.

Answer 4

both, in a way...the shape of the earth is relative to the shape of the atmosphere...the sun reflecting off of and through that atmosphere is what causes the rainbow and its shape...

the atmosphere is full of particles...all these particles interact with each other and the new particles added by the suns rays...

Answer 5

Nothing to do with that. It's hard to explain easily. Check out the reference. But it is becuase rainbows are cirlces around the anti-solar point. You only get to see part of it - an arc with curvature.

Answer 6

isnt it light that does that