Rainbows are one of the few things on Earth nobody hates. Can there be enough of them – or even too many? On rare occasions, you might have encountered a double rainbow before. But is it even physically possible to find a triple rainbow?
Among the many wonders on planet Earth, rainbows are known to every child. They frequently appear after rain, or more exactly: They appear when plenty of water drops are in the air in front of you and sun light shines onto them from behind you. Climate scientist and cloud expert Yi-Ling Hwong from the Muller research group revisits rainbow basics: “White sunlight consists of the whole spectrum of colors. As an electromagnetic wave, the light’s color is defined by its wavelength with purple being the shortest and red being the longest wavelength. Now, when passing through the surface of a droplet, the border of air and water, every wavelength, meaning every color inside white light, is being bent in a different angle, dispersed into a rainbow.”
As red light is refracted less then blue light, it is seen at the outer rim and blue at the inner one. This first kind of rainbow is called primary arc. However, there are double rainbowstoo. For secondary arcs, the rays get reflected twice inside the droplet. At each reflection inside the droplet, a little light is lost. Due to the double reflection, the intensity of the secondary arc is lower and the color order reversed.
“First, yes, they exist”, clarifies Hwong. “Yet, a true third-order rainbow should not be confused with the much more common phenomena of supernumerary bows and reflection rainbows.” Third-order or tertiary rainbows originate from three reflections inside the droplet. In contrast to primary and secondary bows, rays leave the droplet heading away from the sun. Hence, to see a tertiary rainbow, one must look towards the sun. However, at an intensity only one fourth of the primary arc, the bright sunlight makes the rainbow almost impossible to spot. It was only in 2011, in the journal Applied Optics, that first photographic evidence was published. So, stay vigilant for rainbows – you may discover something new.
What about triple rainbows? “First, yes, they exist”, clarifies Hwong. “Yet, a true third-order rainbow should not be confused with the much more common phenomena of supernumerary bows and reflection rainbows.” Third-order or tertiary rainbows originate from three reflections inside the droplet.
In fact, they're so rare that prior to a 2011 image that we'll talk about later there had only been five verified reports of triple rainbows in 250 years [source: Byrd]. Let's get a quick tutorial in how rainbows work.
Only five tertiary rainbows — the scientific term for three rainbows arcing through the sky at once — have been spotted in the last 250 years; others have been dismissed by the scientific community as hoaxes.
As you may have guessed, light can bounce three times off the inner surface of the raindrop before exiting, creating a third-order rainbow; or bounce four times, creating a fourth-order rainbow; and so on. However, the third-order and higher-order rainbows are so faint that they are almost never seen by the naked eye.
The two double rainbows are different than true quaternary rainbows, which are incredibly rare, says Lee. There have only been four or five scientifically documented sightings of quaternary or tertiary rainbows since 1700, he says.
One of the rarest forms is multiple, or double, rainbows. They occur when several rainbows form in the same place at the same time. It takes at least one primary rainbow to generate this sight, as well as several other secondary rainbows. There is always space in between each one.
What about triple rainbows? “First, yes, they exist”, clarifies Hwong. “Yet, a true third-order rainbow should not be confused with the much more common phenomena of supernumerary bows and reflection rainbows.” Third-order or tertiary rainbows originate from three reflections inside the droplet.
The two arcs that parallel each other are a traditional double rainbow. That third arc that's a bit askew and seems to go vertically off the water? That's called a "reflection rainbow " being created by a virtual second sun -- namely sunlight reflecting off the calm waters of Harney Channel.
“Few people have ever claimed to see three rainbows arcing through the sky at once. In fact, scientific reports of these tertiary rainbows were so rare that until now many scientists believed sightings were as fanciful as Leprechaun's gold at a rainbow's end.” - Optical Society of America.
Most likely people claiming that they stood inside a rainbow are making it up, because it's an age-old fantasy in some cultures. Or they were dreaming, or they incorrectly reconstruct the event from imprecise memories. A rainbow is formed by the reflection and refraction of light from the Sun by water droplets.
There are 12 different kinds of single arc rainbows that are decided based on the colors, strength of the bands, and supernumerary bows that appear, or don't appear, in the arc. Here are the basics: RAB-1 has all the colors visible, strong Alexander band, and supernumerary bows.
According to EarthSky, a circular rainbow is a very rare sight, requiring sky conditions to be "just right." "And even if they are, the bottom part of a full-circle rainbow is usually blocked by your horizon," the science and nature website adds. "That's why we see rainbows not as circles, but as arcs across our sky."
Along with refraction, the light can be split into separate bands of colored light, deepening the effect. This arc of shimmering color can span the horizon, which is why it's called a circumhorizontal arc. Fire rainbows are rare, but when they do appear, they can span hundreds of miles and last for hours.
A moonbow (sometimes known as a lunar rainbow) is an optical phenomenon caused when the light from the moon is refracted through water droplets in the air. The amount of light available even from the brightest full moon is far less than that produced by the sun so moonbows are incredibly faint and very rarely seen.
Red rainbows are incredibly rare and are seldom witnessed. Several factors contribute to their infrequency: Low Sun Angle: Red rainbows require a low sun angle, meaning they can only be observed during early morning or late afternoon when the sun is near the horizon.
A baby born after three miscarriages, stillbirths, or deaths is known as a "triple rainbow baby." Why are rainbow babies so special? Because they follow a loss, rainbow babies represent hope and happiness in the face of sadness and grief.
Introduction: My name is The Hon. Margery Christiansen, I am a bright, adorable, precious, inexpensive, gorgeous, comfortable, happy person who loves writing and wants to share my knowledge and understanding with you.
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