El arco iris It is one of the most beautiful and fascinating meteorological phenomena in existence. It is formed when the sun’s rays pass through water droplets suspended in the atmosphere. This process fractures the white light of the sun into a visible spectrum, which we usually perceive as a rainbow. The phenomenon has inspired scientists, philosophers and artists for centuries, and continues to amaze those lucky enough to see it.
The colours of the rainbow are characteristic and always appear in the same order. They are made up of seven well-defined colours: red, orange, yellow, green, blue, indigo and violet.
How is a rainbow formed?
The formation of a rainbow is a natural process that occurs due to the refraction, reflection, and scattering of light. White sunlight passes through water droplets in the atmosphere, causing it to refract (bend). Inside the droplets, the light is reflected once off the inner surface and then scattered into different wavelengths, which correspond to different colors. The result is a spectrum of colors that never ceases to amaze us. It is important to note that the angle of the light is crucial. Sunlight must enter the raindrops at an angle of 42 degrees for a rainbow to form. This phenomenon is observed after rain, or even during it, whenever sunlight strikes the droplets suspended in the air. Isaac Newton was the first to decompose white light using a prism and discover that the rainbow phenomenon was due to the refraction of light.
Colors of the rainbow: a perfect sequence
The rainbow is made up of seven colors, which always appear in the same order, due to the wavelengths of visible light that are refracted in the water droplets. These colors are: red, orange, yellow, green, blue, indigo and violet. Each has a specific wavelength that determines its location in the visible spectrum of the rainbow.
The Red color
El Red Red is the first color of the rainbow and the outermost in the band of colors. This is because it has the longest wavelength of all, allowing it to be refracted less than the other colors. Red symbolizes energy and vitality, and is one of the first colors detected by the human eye.
The color orange
The second visible color in the rainbow is orangeDerived from the mixture of red and yellow, orange evokes creativity and enthusiasm. Although it is often perceived as less intense than red, it is still a prominent color in the most vivid rainbows.
Yellow color
El yellow It is one of the brightest colours of the rainbow and is associated with light and positive energy. It is located in the centre of the visible spectrum, which makes it a transition colour between warm (red and orange) and cool (green and blue).
The color green
El Verde Green marks the beginning of cool colours. It represents nature, growth and serenity. In colour science, green is associated with life and regeneration, and its appearance in the rainbow is a sign of this same vitality.
The color blue
The fifth color of the rainbow is azulThis color has a shorter wavelength than green, which puts it towards the cooler side of the spectrum. Blue is emblematic of calm and stability, and although it is often seen less intensely in weaker rainbows, under optimal conditions, it shows up very clearly.
The color indigo
El indigoIndigo, also called indigo, is a color that is difficult for the human eye to distinguish, often leading to the perception that there are only six visible colors in the rainbow. Indigo is a deep mixture of blue and violet, giving it a mystical and enigmatic hue.
The color violet
Finally, the violet Violet closes the rainbow spectrum. This color is at the end with the shortest wavelengths, making it the most refracted color of all. Being at the inner edge of the arc, violet appears to gently blur, creating a soft contrast with the nearby blue.
Scientific explanation of the rainbow
The science behind the rainbow explains this phenomenon through the laws of refraction, dispersion, and reflection of light. When light strikes water droplets, some rays are reflected inside, while others pass through. As white light passes through the water, the different wavelengths (colors) separate, forming the visible spectrum of the rainbow in the sky. The seven colors recognized in the rainbow comprise the visible light spectrum that can be perceived by the human eye. Although the rainbow appears to have a limited number of colors, the reality is that the light spectrum is continuous and exhibits infinite gradations of color, but the human eye can only distinguish certain specific sets of wavelengths.
Why does the rainbow have an arc?
The rainbow’s characteristic arc shape is due to the geometry of light and water. The arc is a complete circle, but we generally only see the upper half because of our position on Earth. This happens because light rays refract at a fixed angle of 42° in the water droplets, creating the rainbow’s circular shape. The size of the water droplets and the sun’s position in the sky also affect the rainbow’s visibility. That’s why rainbows are more intense and colorful in the early morning or late afternoon, when the sun is lower in the sky. In short, the rainbow is one of the most spectacular and complex meteorological phenomena, resulting from the interaction of sunlight with water droplets in the atmosphere. With its perfect combination of colors and iconic shape, this phenomenon has inspired wonder in scientists, artists, and people from all cultures throughout history.