There's nothing more beautiful than waking up in the morning and seeing a rainbow , right? This phenomenon is one of the most interesting, especially considering that it only occurs on Venus and here on planet Earth.
How is it formed? What are the colors of the rainbow and in what order do they appear? We'll talk about this and much more here, in this special feature on one of the meteorological phenomena that has captivated and continues to captivate humanity.
The human eye, capable of seeing amazing phenomena
To understand what a rainbow is, how it forms, and the colors we see, I wouldn't want to start this article without first explaining a little about how our eyes see . This way, it will be easier for you to understand, and you'll surely enjoy it much more the next time you see one.
Believe it or not, the human eye is one of nature's greatest creations (yes, even if you have to wear contact lenses). Our eyes are very sensitive to light (which, by the way, is white, meaning it's composed of red, green, and blue light), but what appears to us as one color is actually another. Why? Because they absorb a portion of the light illuminating the object and reflect a smaller portion . In other words, if we see a white object, what we're actually seeing are the basic colors of the spectrum mixed together. Conversely, if we see the object as black, it's because it absorbs all the electromagnetic radiation of the visible spectrum.
So, what is the visible spectrum? It's simply the electromagnetic spectrum that the human eye can perceive. This radiation is known as visible light, which is what we can see or distinguish. A typical healthy eye can respond to wavelengths from 390 to 750 nm. Also, if you're interested in learning more about how light is formed, I encourage you to read the article on what light is.
what is the rainbow?
This beautiful phenomenon occurs when sunlight passes through tiny water droplets suspended in the atmosphere , creating a colorful arc in the sky. When a ray of sunlight is intercepted by a water droplet, the droplet breaks it down into the colors of the visible spectrum and simultaneously deflects it; in other words, the ray of sunlight is refracted both as it enters and exits the droplet. For this reason, the ray retraces its path. Furthermore, some of the light refracted upon entering the droplet is reflected back and refracted again as it exits.
Each droplet appears a different color , so those that appear the same color clump together to create one of nature's most beautiful spectacles. If you'd like to delve deeper into how these colors form, you can consult the article on the mystery behind iridescent cloud colors . You can also learn about optical refraction , which is fundamental to rainbow formation.
What are the colors of the rainbow?
The colors of the rainbow are seven, and the first color is red. They appear in this order:
- Red
- Orange
- Yellow
- Green. Green gives way to the so-called cold colors.
- Blue
- Indigo
- Violeta
When it occurs?
Rainbows occur on rainy days (usually mostly sunny days) or on days with high humidity . In both cases, the sun is visible in the sky, always behind you. For more information, you can look up the inverted rainbow , an interesting phenomenon related to rainbow formation.
Can there be double rainbows?
Double rainbows are not very common, but they can occasionally be seen. They form when sunlight enters the lower half of a raindrop and bounces back after two internal bounces . As it does so, the rays cross and exit the droplet in reverse order, producing the seven colors of the rainbow, but inverted. The second rainbow is fainter than the first, but it will be more visible than the third if, instead of two internal bounces, three occur.
The space you see between the rainbows is called the " Alexander's Dark Zone ," and if you'd like to learn more about double rainbows, you can read the article on double rainbows . I also recommend reading about the amazing phenomenon of fire clouds , which are a spectacular sight.
Curiosities about the rainbow
This phenomenon has been occurring for millions and millions of years, but the reality is that until three centuries ago, no one had attempted to provide a scientific explanation . Until then, it had been considered a gift from God to humankind after the Great Flood (according to the Old Testament), it was also seen as a necklace that would remind Gilgamesh of the flood (according to "The Epic of Gilgamesh"), and for the Greeks, it was a messenger goddess between heaven and earth called Iris.
More recently, in 1611, Antoinius de Demini presented his theory, which was later refined by René Descartes. But it wasn't they who established the official theory of rainbow formation; that honor belongs to Isaac Newton , who also studied how light can be divided into different colors and whose work is fundamental. This great scientist was able to demonstrate, with the help of a prism, that the white light of the sun contains the colors red, orange, yellow, green, blue, indigo, and violet— the colors of the rainbow. If you're curious about how light can display different colors, I encourage you to read about Newton's prism.
Have you ever seen a double rainbow? Do you already know what the colors of the rainbow are?
