We always see half rainbow from ground. But it looks completely circular when we see it from high altitude.

 

Rainbows are a natural phenomenon that has fascinated humans for centuries. The beauty and wonder of a rainbow is something that many people have experienced at some point in their lives. However, there is a common misconception about how rainbows appear from different vantage points. From the ground, we typically only see half of a rainbow, but from high altitudes, a rainbow appears as a complete circle. In this essay, we will explore the science behind this phenomenon and why it occurs.

First, it is important to understand what causes a rainbow. Rainbows are formed when sunlight is refracted, or bent, as it passes through raindrops. This causes the light to be separated into its component colors, creating a spectrum of colors. This process is known as dispersion. When the dispersed light is reflected back towards the observer, it forms a circular arc of colors.

When we view a rainbow from the ground, we are limited in our perspective by the curvature of the Earth. We can only see the part of the rainbow that is above the horizon. This is why we only see half of the rainbow. However, from high altitudes, such as from an airplane or a mountaintop, we are able to see more of the rainbow, and it appears as a complete circle.

The reason for this is related to the way that light is refracted as it passes through raindrops. The amount of refraction that occurs depends on the angle at which the light enters and exits the raindrop. When we view a rainbow from the ground, the angle between the incoming sunlight and the observer's eye is approximately 42 degrees. This means that the light is refracted by about 42 degrees as it enters the raindrop and then again as it exits the raindrop. This causes the light to be dispersed into its component colors, forming a half-circle of colors in the sky.

However, when we view a rainbow from high altitudes, the angle between the incoming sunlight and the observer's eye is much larger. This means that the light is refracted by a greater angle as it enters and exits the raindrop, causing the dispersion of colors to be more spread out. This results in a complete circle of colors, rather than a half-circle.

It is also worth noting that the size of the rainbow changes depending on the observer's altitude. The higher the observer, the larger the rainbow appears. This is because the observer's perspective changes, allowing them to see more of the rainbow.

In addition to the scientific explanation for why rainbows appear as half-circles or complete circles, there are also cultural and symbolic meanings associated with rainbows. In many cultures, rainbows are seen as a symbol of hope and renewal. They are often associated with positive emotions such as joy, happiness, and wonder.

In conclusion, the phenomenon of why we see a half-rainbow from the ground but a complete circle from high altitudes can be explained by the way that light is refracted as it passes through raindrops. When the angle between the incoming sunlight and the observer's eye is large enough, the dispersion of colors becomes more spread out, resulting in a complete circle of colors. While rainbows have a scientific explanation, they also hold cultural and symbolic significance for many people. Regardless of how we view them, rainbows are a beautiful and awe-inspiring natural wonder that will continue to captivate and inspire us for generations to come.