“It is pointless to add another color to the rainbow,” said Shakespeare.
This is because rainbows are the most beautiful of all weather phenomena.
Rainbows are the art of water, light, and air.
It is a magnificent rhythm woven by the warp and woof of the atmosphere.
The moment-to-moment changes are exquisite. The complexity and simplicity of the colors is a wonder to behold.
Rainbows in mythology
The ancients believed that all natural phenomena in the sky were signs of divine activity.
Thus, a rainbow following a fierce storm signaled the presence of a benevolent deity.
In particular, rainbows straddle the line between heaven and earth.
As such, it was a special symbol of communication with the gods.
In ancient Greece, the rainbow was a manifestation of the gods.
It was the goddess Iris, who delivered messages to people from Mount Olympus.
Iris got her Latin name from the flower Iris, which means supreme beauty.
As the rainbow goddess, Iris’ most important task was to deliver news.
She descends to the world of men by treading on rainbows, dressed in clothes made of dewdrops.
In Norse mythology, the gods built a bridge between the heavens and the inhabited earth.
This is the rainbow bridge called Bifrost.
The rainbow is the channel of communication between the gods and people.
The Umbanda and Condomble indigenous peoples of Brazil and the Santeria people of Cuba assign similar symbolism to the rainbow.
In Tibet, humans and gods are united by the rainbow, which is a pathway between the higher realms where gods live and the lower realms where humans live.
In Tibet, humans and gods are said to ascend and descend on heavenly ladders made of rainbows.
In African cultures, such as the Yoruba people of Nigeria, rainbows are seen as energy flowing between heaven and earth.
They identify it with the sky serpent, which they see as an auspicious symbol.
The Incas associated the rainbow with the sun god.
The ancient Chaldeans saw the rainbow as a great bow held aloft by a great goddess after a great flood.
The Bantu kings of the Sahara claimed they were descended from the rainbow.
They utilized the rainbow to rule. The Chinese Carapace Gate is the oldest documented meteorological phenomenon.
The rainbow (虹) is thought to be “a two-headed monster (a dragon or snake type) drinking from a river.
When they saw a rainbow, they would tremble and smoke divining sticks.
In Chinese tradition, the rainbow is a symbol of the Heavenly Dragon, the unity of heaven and earth.
In the Christian world, however, the rainbow appears in the story of Noah’s flood.
It’s a symbol of God’s forgiveness and love.
The science of rainbows
So, how do rainbows happen
It was the 17th century philosopher Rene Descartes who scientifically characterized the phenomenon.
Since then, many atmospheric scientists have elaborated on how they work.
Rainbows are formed by raindrops floating in the sky on one side.
Sunlight from the other side of the raindrops is refracted, spectralized, and reflected, making it visible to our eyes.
Rainbows are caused by white sunlight passing through air and water and bending into different colors.
This is light refraction.
Refraction occurs when different colors of light pass through raindrops at different speeds.
Red travels slightly faster than purple.
This difference in speed causes it to split into different colors.
This splitting of colors is called spectroscopy.
Rainbows are visible to our eyes because the sun’s rays are reflected at a certain angle in the raindrops. It’s a reflection.
What we usually see as a single rainbow is called a primary rainbow.
It’s a single reflection of sunlight in raindrops. It’s also called a nimbus rainbow.
It appears at a visual radius of 40 to 42°, centered on the extension of the line connecting the sun to the observer.
Think of it as a sunlight spectrum with violet on the inside and red on the outside.
Although slightly rarer, double rainbows are also common.
In a double rainbow, a secondary rainbow is visible outside the primary rainbow. The secondary rainbow is sometimes called a dark rainbow.
Unlike the primary rainbow, it has a wider viewing radius. It appears with a viewing radius of 50 to 53°.
It’s created when light reflects twice inside a raindrop.
The colors of the rainbow are reversed from the primary rainbow, with red on the inside and purple on the outside.
Tertiary rainbows appear in the opposite direction of the first and second rainbows, i.e. towards the sun, at a radius of 38-42°.
It is created when light is reflected three times within a raindrop.
However, it becomes increasingly difficult to actually see them because each reflection is significantly darker.
There can also be four or more rainbows.
It’s not easy to see more than three rainbows.
But here’s the thing.
When you see a rainbow on the ground, you can only see a semicircle in the shape of an arrow.
But from the air, rainbows are circular.
Think of a water droplet in three dimensions.
When sunlight hits a water droplet, the light from the droplet forms a cone, like an ice cream cone.
If the point of the cone (the apex) is where you look, the rainbow looks like the circumference of a circle, which is the base of the cone.
But why is the shape of the rainbow we see a semicircle?
In most cases, the rainbow is covered by the ground, which makes it look like a semicircle.
However, if you were to look at a rainbow from an airplane (the airplane’s position is the apex of a cone), the rainbow would definitely look like a circle.
That’s why you can’t see a squashed rainbow, and why you can’t see the sides or back of a rainbow.
Rainbows are always seen from the front.
There are also different types of rainbows.
The rainbows that appear inside the primary rainbow and outside the secondary rainbow are supernumerary rainbows, which are thought to be caused by light interference from the water droplets that create the primary and secondary rainbows.
If the sun is hovering over a calm body of water, such as a lake, the sun’s reflection on the lake also produces a pale rainbow, which overlaps the rainbows and is called a semi-supernumerary rainbow.
Water droplets with a radius smaller than 30 μm (micrometers), such as fog, can produce a wide rainbow with only a thin band of color at 37-40° from the point of convergence, which is called a fogbow.
Rainbows can also be produced by moonlight instead of sunlight, which is called a moonbow.
If a rainbow occurs near sunset or sunrise, it can be a red, monochromatic rainbow.
Are there really seven rainbow colors?
Newton was the first to experimentally show that the rainbow is made up of multiple colors.
When he separated the spectrum of light with a prism, he found seven colors: red, yellow, blue, red, white, and blue.
After that, Newton’s color wheel became immovable.
However, when light is actually separated, there are more than 100 colors that humans can distinguish.
So why did Newton divide the rainbow into seven colors?
There are several explanations.
One is that in the Bible, seven was a sacred number for a perfect number.
Medieval Europe was under the overwhelming influence of Christianity.
It’s also why we see seven scales in music and seven stars: Sun-Moon-Mars-Mercury-Jupiter-Venus-Saturn.
In fact, the number of colors in the rainbow varies from culture to culture.
In the Anglo-American world, it’s common to see six colors in the rainbow, not including indigo.
The Maya, the indigenous people of Mexico, saw it as five colors.
Some peoples see only two or three colors. In the East, they saw the rainbow in five colors.
So these five colors, the five colors, are not literally five colors.
They are the five colors in the sense of all the colors that can exist in the universe.
In the East, the five colors are the five pure, unadulterated, basic colors as described in the Yin Yang Five Elements.
They were called the five colors, the five elements.
Therefore, the rainbow that the fairy rides down is not a “seven-color rainbow”.
It was a rainbow of five colors.
By looking at the rainbow, we see that the categories of colors vary from culture to culture.
Rainbows are getting harder to see
“My heart leaps when I look at the rainbow in the sky / It did when I was a child, and it does now that I’m a man / And it will continue to do so when I’m old / Or else I’ll die” (Wordsworth’s poem). As a child, I remember running with my friends to the end of the rainbow when it appeared.
We thought there was treasure buried at the end of the rainbow.
In France, you could find a large pearl, in Greece, a golden key, in Ireland, a gold watch, and in Norway, a golden bottle (甁).
As it turns out, the rainbow retains its shape as you approach it and recedes backwards.
That’s why no one ever reaches the end of the rainbow….
In Germany, there is a saying that if you see a rainbow, only good things will happen to you for the next 40 years.