If Rainbows Are Circular, Why Do We Only See Arches
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Often times after a wild thunderstorm a calm glamorous arc of different colors, rainbow, appears and it always feels like a blessing. What many people don’t know is that rainbow does not form an arc but actually a complete circle of different colors in the line. This is because in most cases we never see the complete rainbow so we just assume it’s just the arch but actually, the reason behind this is due to the fact that a piece of the rainbow is mostly covered by the surface and horizon thus we only see the top visible part.
Rainbow formation
For matter, light travels faster in the air than water. When sun rays hit water droplets in the air their speed is reduced instantly thereby refracted as it enters the water droplets, its refracted again by the inner walls and again as it leaves the surface of the water droplets. the change is due to the fact that water is more denser than air. Although sun rays may look one distinct color it is actually composed of various different color rays to make that distinct white light. all these colors differ in their wavelengths that’s why after refraction the colors leave the water drop in different angles forming layers.
The Antisolar point
Given that all these colors disperse at different angles, it’s only possible to view a single color from one drop. This is because the other colors are dispersed at an angle impossible for the eye to see. The antisolar point serves as the center of a rainbow and is 18o degrees away from the sun. This point may be on the ground surface as well as the sky.
The position of this point also relates directly to the position of the sun to determine how an observer either on the ground or in the air is going to view the rainbow. When the sun is really close to the surface, the antisolar point tends to get raised such that the observer is able to see a larger portion of the rainbow. Viceversa, when the sun is quite above the ground or 42 degrees above the surface it gets almost impossible to view even a piece of the rainbow this is due to the lack of enough water droplets between the view and the sun.
This is however different when viewing from above on a misty rainy day. From an aircraft on such a day its easier to
