Nothing quite sparks a sense of wonder like the sudden sight of a rainbow stretching across the sky. From inspiring countless pieces of artwork, mythology, poetry, to etching unforgettable memories in our minds, rainbows have fascinated humans throughout history. However, beyond their enchanting beauty, lies a fascinating world of science and optical phenomena. So, what causes rainbows, and what's the story behind this brilliant display of Nature's hues? Let's dive into understanding light refraction and the logical yet magical science of rainbows.
What Causes Rainbows: The Simple Yet Stirring Physics
At its core, the creation of a rainbow is a game of light and water droplets, orchestrated under certain ideal conditions. When sunlight (or any white light) after a rain shower enters a spherical water droplet, the magic unfolds in three steps: refraction, reflection, and dispersion.
For a rainbow to be visible to the observer's eye, the light must first refract, i.e., bend as it enters the water droplet. This occurs because light slows down when it moves from a less dense medium (air) to a denser one (water). This slowing down of light, in turn, causes it to change direction, an event commonly known as refraction. However, the story doesn't end here. This refracted light then hits the inside surface of the water droplet and reflects off of it, bouncing back towards the other side of the droplet.
The Dispersion of Light: A Symphony of Colors
As the light exits the droplet (another round of refraction), it leaves at an angle allowing the observer to perceive the light as a band of colors rather than just white light, and therein lies the heart of the rainbow phenomenon. This phenomenon is known as dispersion.
Dispersion occurs because each color in white light has its own unique wavelength. When white light refracts, the change in speed experienced by each color is slightly different. This difference in speed causes the colors to spread out, creating a spectrum. The shortest wavelengths (blue and violet light) refract the most while the longest ones (red light) refract the least, causing the colors to spread and form a circle of light - or the brilliant arc we know and love as a rainbow.
Believe it or not, every raindrop dispersed light in this manner but we only see the light from the raindrops which direct the dispersed light precisely to our line of sight.
Continue with us as we journey further into the science of rainbows, exploring more about this colorful arc, and understanding in depth about various types of rainbows, their formation and more.
The Beauty of Dissection
When we talk about the beautiful parabolas in the sky, we look at different elements simultaneously; the sunlight, the rain, and the unique atmospheric conditions. But to understand the reason why a rainbow shape is always the same, we need to dive a bit deeper into the science of it all. Rainbows have been dissected by scientists for a long time and it seems like we've got a good grasp on most of its underlying processes.
The first key factor we need to discuss is the speed of light. When light travels through different mediums (like air and water), its speed changes — this is known as light refraction. When the sunlight hits a raindrop, it slows down, and this causes it to bend and disperse its colors into a spectrum. Each color has its own wavelength, with red boasting the longest and violet the shortest. But since our eyes have a hard time seeing this process, what we see is a combination of all colors, hence, the rainbow.
This rainbow formation happens inside each raindrop. And if you think about it, there are millions of tiny rainbows happening all around us, but we can only see the light reflected from raindrops at a certain angle, which is about 42 degrees from your line of sight. So the circular arc that we all know and love is actually a cluster of these reflections happening in different droplets, but our point of view makes it appear like a semicircular arch.
It’s beautiful, isn't it? And that’s just the basics concerning the formation of rainbows. They are a much more complex and mysterious phenomenon than they seem at first glance.
The Different Types of Rainbows that Exist
While majority of us have seen regular rainbows, there’s more to them than meets the eye. They can be classified into various types depending upon their characteristic features and atmospheric requirements. Let's uncover a few fascinating types of the spectral phenomenon.
Double Rainbows
You might have seen such a surreal spectacle — two rainbows at the same time, with one being dimmer and boasting reversed colors. This sight is a result of sunlight being reflected twice inside water droplets. This double reflection causes the light to exit the droplet at a different angle, producing the second, fainter arc.
Fogbows
As the name suggests, this type of rainbow appears when tiny water droplets are suspended in fog, mist or cloud instead of heavy rain. Their colors are much fainter, with a ghostly white or bluish tint because fog droplets are smaller than raindrops which limit color dispersion.
Sun Dogs
Sun dogs, or parhelion, are a type of atmospheric optical phenomenon where two bright spots appear on either side of the sun. They occur when sunlight refracts through ice crystals in the atmosphere instead of liquid raindrops. These bright spots mimic the color of the sun, often with a hint of a rainbow.
Feel inspired yet? After all, rainbows are the perfect emblem of hope and joy, spreading their colors across the sky. Knowing the science behind them makes the sight even more magical and awe-inspiring, doesn't it?