Physics Classroom says:
The skies have always presented us Earthlings with an array of fascinating displays. The skies have been the stage for arcs of lightning, colorful auroras, halos, sundogs and more. For certain, the rainbow has always been a subject of wonder and awe. Amongst the questions pondered in this gallery will be the question of how does it form? What is the physics behind this fascination?
"One can enjoy a rainbow without necessarily forgetting the forces that made it."
== Mark Twain
Physics Classroom says:
Two things are required for the formation of a rainbow - suspended droplets of water and bright light. The water droplets ,whether from the mist of a sprinkler, the splash of a waterfall, or atmospheric condensation following a storm, are essential. Light, usually from the sun, enters these drops as white light and emerges as a rainbow of colors. The phenomenon is referred to as dispersion - the separation of white light into its component colors.
To learn more about light dispersion, visit The Physics Classroom Tutorial.
"As on the driving cloud the shiny Bow,
That gracious thing made up of tears and light ..."
== Samuel Taylor Coleridge
Physics Classroom says:
Light dispersion is most often associated with light passing through a triangular prism. As light enters the prism, it refracts. As it exits, it refracts again. If opposite sides of the prism are parallel, then the second refraction undoes the first refraction so that there is no dispersion and no overall change in the direction that light is heading. But in a triangular prism, opposite sides are not parallel. The second refraction serves to accentuate the first. And since different colors of light bend varying amounts (ever so slightly), the dual refraction in the same direction results in a slight separation of white light into the various colors that it is composed of.
“The work will wait while you show the child the rainbow, but the rainbow won't wait while you do the work.”
== Author unknown
Physics Classroom says:
Rainbows are formed when a collection of tiny droplets serve as little prisms. If enough of these little prisms fill the sky and if the sun is bright enough, the spectrum of color that emerges from a drop will be reinforced by the light that emerges from neighboring drops. Every droplet is dispersing light into ROYGBIV. The red light that emerges from a water droplet is bent at a slightly steeper angle to the ground compared to violet light. So to see the red light, one one must look higher in the sky. And to see the violet light, one must look slightly lower in the sky. The result is the familiar arc of color that we know as a rainbow.
“Life is like a rainbow. You need both the sun and the rain to make its colors appear.”
== Author Unknown
Physics Classroom says:
There is a very specific geometry that is required of the passing of light into, through and out of a water droplet in order for rainbows to be formed. As mentioned earlier, light refracts twice and reflects once. The reflection is required to bound light back towards our eyes. With the sun at our backs, we can view the bow.
The brightness of the emerging light is greatest when light enters the top of a droplet and emerges from the bottom of the droplet at approximately 42 degrees from the original direction. At other entry and exiting angles, the light is not bright enough to form a visible rainbow.
“Somewhere over the rainbow, skies are blue, and the dreams that you dare to dream really do come true.”
== Lyman Frank Baum
Physics Classroom says:
When the sunlight is bright enough, one might be lucky enough to view a double rainbow. The second bow results from a different geometry than the first bow. Light enters a droplet and refracts twice and reflects twice. The second reflection serves to invert the order of the colors. It also serves to bend the light downward towards the ground at steeper angles. And so the second bow - usually the dimmer of the two - is seen higher in the sky and with the colors reversed compared to the lower bow.
To learn more about rainbow formation, visit The Physics Classroom Tutorial.
"Triumphant arch, that fill'st the sky when storms prepare to part."
== Thomas Campbell
Physics Classroom says:
We are accustomed to looking up above the horizon in order to view a rainbow. What we view is the top portion of what would be an otherwise 360° circle of color. The bottom (and perhaps the middle) of that circle is interrupted by the horizon of the Earth. But when in an airplane, one can often view the full 360° bow.
Once more, the geometry associated with the refraction and reflection of light explains this phenomenon. Light enters the portion of the water droplet on the outside of the bow. It refracts into the droplet, reflects off the opposite side and refracts once more when exiting. At an approximately 42-degree angle between the entry ray and the emerging ray, the colors are most intensified. Whether we look up or down or to the side, it is at this angle relative to light's original direction that we will see the dispersed light emerging from the collection of droplets.
"Rainbows apologize for angry skies."
== Sylvia Voirol
Physics Classroom says:
When viewing a rainbow (or the photos of them as shown in this gallery), one will always notices the brightness of the sky inside the bow. The photo at the right depicts this relative brightness inside the arc. It also depicts the relative darkness that is always viewed in the region between the two bows of a double rainbow.
"Weekends are a bit like rainbows; they look good from a distance but disappear when you get up close to them."
== John Shirley
Physics Classroom says:
As mentioned, the dispersion results from light entering the airborne droplets and refracting twice and reflecting twice. The dispersed light is brightest when the angle between the entering and emerging light is 42°. Yet there are many other angles for which light reflects from the droplet back towards our eyes. These other angles are all less than 42°. We see the interior of the bow because of these smaller angles. Since these smaller angles do not disperse light enough to cause a visible spectrum, the interior of the bow is bright but not colored.
The outer bow is viewed when we look higher in the sky. It's formed by two refractions and two reflections within each drop. The dispersed light that emerges from a drop in this manner emerges at the smallest angle of all the double reflected light. The result is that there is very little light coming to our eyes from the region between the two bows.
"When you reduce life to black and white, you never see rainbows."
== Rachel Houston
Physics Classroom says:
The natural phenomenon of rainbows has historically been a source of inspiration for a collection of thoughts, stories and legends. Poets, songwriters, and philosophers have pondered the phenomenon and penned many ideas that have endured history. These stories and legends remain today - engrained in our culture and passed on from generation to generation. Many of the quotes included within this gallery provide a snapshot of these cultural remnants.
"So shines the setting sun on adverse skies, and paints a rainbow on the storm."
== Isaac Watts
Physics Classroom says:
One of the more popular legends of rainbows is the Irish folk legend regarding the leprechaun and the pot of gold. According to the legend, the leprechaun is a mischievous old man clothed in green who spends his days making shoes. The gold coins he earns for his labor are stored in a pot. The pot of gold is then hidden at the end of a rainbow.
Thus, according to legend, there is a pot of gold hidden at the end of every rainbow. Any person who is ambitious enough and lucky enough to travel to the end of the rainbow will find the pot of gold.
"Sometimes it's important to work for that pot of gold. But other times it's essential to take time off and to make sure that your most important decision in the day simply consists of choosing which color to slide down on the rainbow."
== Douglas Pagels
Physics Classroom says:
Of course, life teaches us the lesson that it isn't easy finding that pot of gold. And once found, there is no guarantee of happiness.
Perhaps a more reliable path to happiness is to learn to appreciate the beauty in others and the splendor in our natural world and to make an effort to understand both. This is what colors our life, gives it flavor and makes it worth the living. As it is said ...
"Don't miss all the beautiful colors of the rainbow looking for that pot of gold."
== Author Unknown
Physics Classroom says:
The Physics Classroom would like to thank all Flickr photographers for capturing the beauty of our natural world and being willing to share it with the rest of us.
We hope that you have enjoyed our gallery on Rainbows. Additional galleries can be found at The Physics Classroom's Galleries page.
To learn more about rainbow formation, visit The Physics Classroom Tutorial.
“We have not the reverent feeling for the rainbow that a savage has, because we know how it is made. We have lost as much as we gained by prying into that matter.”
== Mark Twain
Nothing here yet.
You can save a photo or video to a gallery from its detail page, or choose from your faves here.
Comments