How are Rainbows Formed
We all have seen a rainbow occasionally during or immediately after a rain shower. Most, if not all, of us have pondered on the workings of this natural phenomenon. Indeed, humans have always been fascinated with rainbows. It has various symbolisms in different legends and mythologies, and is often depicted in songs, poems, and paintings.
In spite of its varied romanticized interpretations, rainbows can be easily explained by science. This article provides a detailed explanation about this phenomenon.
What is a rainbow?
A rainbow is an arched light that is separated into bands of parallel color stripes. It appears when the sun s rays are bent and reflected by drops of mist or rain. It is composed of the colors red, orange, yellow, green, blue, indigo, and violet.
What causes a rainbow to form?
Immediately after a rain shower, thousands of water droplets are left floating in the air. As sunlight passes through these spherical-shaped droplets, light is bent and scattered into a continuous band of colors. This light is reflected off the back of the drop and refracted again as it leaves the drop. Thus, the light coming from several of the raindrops create a rainbow.
How does a rainbow get its colors?
The colors of the rainbow are caused by the dispersion of light as it passes through a prism. The prism scatters the different colors of light according to their wavelength. It appears as a spectrum, or a continuous band of colors, as it travels from the prism to the air.
The sun s white light is made up a spectrum of colors that behave like a wave. Sir Isaac Newton demonstrated this fact by letting a beam of sunlight pass through a prism. He proved that sunlight is composed of several colors that the human eye cannot see separately. These are the colors red, orange, yellow, green, blue, indigo, and violet the same colors that compose a rainbow.
Why do the colors appear the way that they do?
Light is bent at different angles for different wavelengths. This is the reason for the order of appearance of the band of colors. Red is least refracted, while violet is refracted the most. The other colors of the spectrum are found between these two. Blue light is shorter than red light. As the area at the back of the droplet has a focal point, the spectrum crosses itself and causes the red light to appear higher in the sky. That is why red forms the outer color of the rainbow, while blue is seen in the middle of the rainbow.
Hence, the color of the rainbow is always seen in the following order: red, orange, yellow, green, blue, indigo, and violet.
Can everybody see the same rainbow at the same time?
Rainbows do not actually exist at one particular location in the sky. Its observable position depends on the sun s position and the observer s location. All raindrops refract and reflect light the same way, but not all the light from the raindrop reaches the observer s eyes. The light that reaches the observer constitutes the rainbow for that observer.
In addition, a rainbow always appears directly opposite the sun from the observer. Hence, a rainbow appears in front of a person whose back is to the sun.
Why is a rainbow shaped like an arc?
Though rainbows appear as a bow in the sky, they are actually formed as a circle. The light from the sun is refracted by droplets at approximately 42 . This angle is so big that the rainbow appears at the middle point opposite the sun.
The arc is actually part of the circle of light cut off by the horizon. A larger portion of the rainbow can be seen when the sun is low in the sky. The full circle can be seen at high altitudes, such as in an airplane, because the horizon does not block the observer s point of view.
How can I make my own rainbow?
During a sunny day, take a spray gun and fill it with water. Stand outside with the sun behind you. Spray water in front of you in all directions. Rainbows should be popping all around you.
