The rainbow is a beautiful natural phenomenon that has fascinated people throughout history. It is formed when sunlight is refracted and dispersed by water droplets in the air, breaking white light into its full spectrum of color. But what exactly are the sequence of colors that make up a rainbow? Let’s take a closer look at the 7 colors of the rainbow in order.
The Origin of the 7 Colors
The sequence of colors that form a rainbow originate from the dispersion of sunlight by water droplets in the atmosphere. When a ray of sunlight passes through a water droplet, it slows down and bends, separating into its component wavelengths. The different wavelengths of light refract at slightly different angles, causing them to fan out into the familiar rainbow spectrum.
Sir Isaac Newton was the first to discover that sunlight is composed of a spectrum of different colored lights back in 1666. He demonstrated this by passing a narrow beam of sunlight through a glass prism, which separated the light into the colors of the rainbow due to the prism’s refractive properties. Newton identified seven main colors present in the sunlight: red, orange, yellow, green, blue, indigo and violet. These seven color names provided the basis for the sequence of colors recognized today in rainbows.
The 7 Rainbow Colors in Order
The colors of the rainbow in order from top to bottom are:
| Red |
| Orange |
| Yellow |
| Green |
| Blue |
| Indigo |
| Violet |
So when you see a rainbow, the red band will always be at the top and the violet band at the bottom. This sequence of 7 colors has become well-established in scientific sources and popular culture. But you may notice that not all rainbows clearly show all 7 distinct colors. Sometimes the indigo band may be difficult to distinguish from the blue or violet. The apparent number of colors can also depend on the size and brightness of the rainbow. But in theory, there are always 7 spectral bands present.
The Visible Spectrum
The 7 rainbow colors correspond to wavelengths of light that are visible to the human eye. The visible spectrum is part of the full electromagnetic spectrum, which includes radio waves, microwaves, infrared, ultraviolet, x-rays and gamma rays.
The visible wavelengths make up only a small fraction of the full spectrum, from about 380 to 750 nanometers. This range can be further broken down into the 7 main rainbow colors:
| Color | Wavelength (nm) |
| Violet | 380-450 |
| Blue | 450-495 |
| Green | 495-570 |
| Yellow | 570-590 |
| Orange | 590-620 |
| Red | 620-750 |
As you can see, there is some overlap between the ranges of adjacent colors, so the divisions are not absolute. But each color band corresponds to a certain wavelength range that stimulates the color receptors in our eyes.
Why Is the Sequence Always the Same?
You might be wondering why rainbows always show the 7 color bands in the same order. This has to do with the inherent properties of light and the way it interacts with water.
Red light has the longest wavelengths of visible light, while violet has the shortest. When white light enters a water droplet, the longer red wavelengths are bent the least while the shorter violet wavelengths are bent the most. This separates the component colors based on their refractive properties.
Red always appears at the top since its light is bent the least, exiting the raindrop close to the original path. Violet exits at a wider angle relative to the original path since its shorter wavelength undergoes more angular deflection. The other colors fan out in sequence between the outer violet band and inner red band.
So in essence, rainbows will always show red on the outside and violet on the inside due to fundamental principles of optics and the physics of how different colors of light are refracted. This reliable sequence is why Roy G. Biv is a helpful mnemonic for remembering the order!
Fun Facts About Each Color
Now let’s take a quick look at some interesting facts about each of the 7 rainbow colors:
Red
– Longest visible wavelength
– First color Sir Isaac Newton identified when he passed sunlight through a prism
– Associated with love, passion and excitement
Orange
– Blend of red and yellow
– Many citrus fruits have orange color
– Reminds people of sunshine and warmth
Yellow
– Middle color of the visible spectrum
– Associated with happiness and optimism
– Makes babies cry more than any other color
Green
– Restful to the human eye
– Dominant color in nature and foliage
– Associated with health, renewal and environment
Blue
– One of the most popular colors
– Associated with depth, stability and tranquility
– Lowest natural wavelength humans can see
Indigo
– Mix of traditional blue and violet
– Isaac Newton added indigo to fit the 7 colors of the rainbow
– The color of creativity and meditation
Violet
– Shortest wavelength visible to humans
– Blend of red and blue light
– Associated with spirituality and imagination
So in addition to their scientific properties, each color also has its own interesting symbolic associations and influences on the human mind. The rainbow truly contains a rich spectrum of meaning.
How Rainbows are Formed
To understand why rainbows show their signature color sequence, it helps to visualize how rainbows take shape optically:
1. Sunlight enters a water droplet – A ray of sunlight shines on a water droplet at a specific angle, entering one side of the spherical droplet.
2. Dispersion and internal reflection – The sunlight is slowed down and refracted within the droplet, causing the component wavelengths to separate and reflect internally off the back surface.
3. Light exits the droplet – The dispersed light wavelengths exit the droplet on the opposite side, fanning out at slightly different angles based on refractive index.
4. Light reaches the observer – An observer positioned at the right angle sees the array of wavelengths as the familiar rainbow spectrum of red, orange, yellow, green, blue, indigo and violet.
So it is the process of dispersion, internal reflection and angular separation of light within myriad suspended raindrops that creates the rainbow’s continuous spectrum of color.
Double Rainbows
Sometimes we are treated to an even more spectacular sight – a double rainbow! A double rainbow simply forms from additional internal reflections within the raindrops.
First Reflection: Creates the primary rainbow with red on top.
Second Reflection: The light reflects again, creating a secondary inverted rainbow with violet on top.
The second reflection is dimmer than the first, which is why the secondary bow is fainter and often harder to see. But the sequence of colors is reversed.
Double rainbows reinforce that the order of colors stemming from dispersion is always fixed, no matter how many internal reflections occur!
Rainbows in Culture and History
Rainbows have fascinated humankind across cultures and history:
– In Greek mythology, the rainbow was considered to be a path made by a messenger between the gods and humans.
– Rainbows play an important role in many world religions, serving as a symbol of God’s covenant, mercy or promises.
– In Irish lore, leprechauns were said to hide pots of gold at the ends of rainbows.
– The Inuit people believed that the spirits of loved ones existed at the end of rainbows.
– The rainbow flag has been adopted as a symbol of the LGBT community and social movements.
– Rainbows are often used in art and culture to represent hope, peace, diversity and optimism.
So for thousands of years, rainbows have captivated our imagination and been infused with rich meaning. The consistent sequence of rainbow colors has been both a source of scientific curiosity and artistic inspiration.
Ways to Remember the Order
The sequence of colors in a rainbow is always fixed, but here are some handy ways to memorize the proper order:
– Roy G. Biv – Use this classic mnemonic device, with each letter representing the first letter of a rainbow color.
– A Colorful Story: Make up a silly phrase like “Really Orange Yaks Graze Blue Ivy Vigorously.”
– Visualize a rainbow – Picture the rainbow’s shape and colors in your mind. Red is on top since it’s refracted the least.
– Associate moods with colors: “Red for Anger, Orange for Vitality, Yellow for Joy…” etc.
– Learn the sequence song – Sing or listen to “I Can Sing a Rainbow” to memorize.
– Observe real rainbows – Take note of natural rainbows and reinforce the proper color ordering.
With practice, knowing your ROY G. BIV becomes second nature!
Conclusion
The colors of the rainbow originate from sunlight’s visible spectrum and always appear in the sequence of red, orange, yellow, green, blue, indigo and violet. This reliable order stems from the physics of light dispersion and reflection in water droplets. While not every rainbow may show all 7 colors vividly, the sequence is fundamentally fixed due to the inherent properties of different wavelengths of light. As a fascinating interplay between optics, nature and our perception, rainbows continue to offer scientific insight and inspire human imagination. So next time you encounter one of nature’s most splendid wonders, look closely to see all 7 colors!
