Spectacular Spectrums: 10 Amazing Rainbows

By Steve


Gloriously hued and ephemeral in nature, rainbows are one of the most beautiful sights the skies have to offer. They come in a wide variety of shapes, styles, sizes and yes, even colors. These ten amazing arcs show what happens when Mother Nature gets out her paintbox.

Classic Rainbows

(image via: Rock The Seesaw)

Most everyone has seen a classic, garden-variety rainbow – sometimes in their gardens while watering their plants with a misting spray.

(images via: A Womens Circle and Hawaii Pictures)

Natural rainbows are made up of 6 colors: red, orange, yellow, green, blue and violet. The intensity of each color may vary due to atmospheric conditions and the time of day (more on that later).

Circular Rainbows

(images via: Dot Photo and Getty Images)

The rainbows most of see are actually arcs of perfect circles (with radii of exactly 42 degrees, according to Descartes), though viewing a complete rainbow is difficult as the ground has a habit of getting in the way.

(image via: Neatorama)

The advent of powered flight and aerial photography has enabled the magnificence of circular rainbows to be revealed to an awestruck public. Of course, if an airplane isn’t available a really high mountain will do.

Secondary Rainbows

(images via: Little Dreamers Daycare, Grzegorz Blachuta/TrekEarth and Royer Oaks Observatory)

Primary rainbows are often accompanied by secondary rainbows that are usually thinner and dimmer than the main rainbow. Here’s a bit of trivia that may come in handy at parties or around the water cooler: the area between primary and secondary rainbows that appears darker than the surrounding sky is called “Alexander’s Band”.

(image via: CuriousLee)

Secondary rainbows are remarkable for one particular characteristic: they display the spectrum in reverse order from that of a primary rainbow. It’s not something most people are familiar with, as is seen in the photoshop rendering above. Though sketched from the artist’s memory of an actual event, the repeated structure of both rainbows shows that it’s not an accurate portrayal.

Red Rainbows

(images via: Mark Kilner, Unexplained Mysteries and Earth Science)

Red rainbows are usually seen at sunrise or sunset when the thickness of the earth’s atmosphere filters out blue light leaving more red or orange light for water droplets to reflect and refract. The result is a rainbow with the more reddish end of the spectrum greatly enhanced.

Sundogs

(images via: The Weather Doctor, Kan Ahaw and W7ftt)

Sundogs are not rainbows per se, but share many of their visible attributes. Most commonly seen low in the sky on a bright winter’s day, sundogs are created when sunlight shines through ice crystals high in the atmosphere. Sundogs are red on the inside and violet on the outside with the rest of the spectrum crammed in between. The thicker the concentration of ice crystals in the air, the more defined the structure of a sundog and its associated arcs becomes.

(image via: G.Dargaud)

Moonlight can be acted on by ice crystals to form – you guessed it – “moondogs”. The image above was taken in Antarctica where, due to frigid air temperatures and blowing snow, sundogs and moondogs are extremely common.

Fogbows

(image via: WWU Planetarium)

Fogbows are much rarer than rainbows because certain narrow parameters must align to create them. For one, the light source must be behind the observer and low to the ground. Also, any fog to the rear of the observer must be very thin so that sunlight can shine through to the thicker fog in front.

(images via: Extreme Instability, Space Weather and STOLspeed)

Many fogbows display paler colors compared to rainbows and some are mainly white. This is due to the fog being composed of exceedingly fine water droplets.

Waterfall Rainbows

(images via: Environmental Graffiti and Canada Photos)

Waterfalls kick a constant stream of mist into the air and the atmospheric saturation goes on constantly, regardless of the weather. This makes waterfalls excellent photographic companions to rainbows! The above selection of images pairs some of the world’s most famous waterfalls with some equally stunning rainbows.

(image via: Schools Wikipedia)

A variation of waterfall rainbows are “spray bows”, formed on sunny days when wind kicks up ocean or lake waves and the air becomes saturated with mist and moisture.

Fire Rainbows

(images via: ABC3340weather, Sujathafan and Crystalinks)

Fire rainbows are not actually rainbows and have no connection with fires. The true name for this exquisitely beautiful optical effect is “circumhorizontal arc”.

(image via: Opacity)

The phenomenon can only be viewed under certain precise conditions: the cirrus clouds that act as prisms must be at least 20,000 feet high and the sun must strike them when it is at an elevation of 58 to 68 degrees. Fire rainbows are never seen at locations situated more than 55 degrees north or south.

Moonbows

(images via: COLOURlovers)

Moonbows, like moondogs, are the lunar counterpart to rainbows. They’re also much more difficult to witness due to the requirement of a passing rainstorm and, ideally, a bright full moon unblocked by clouds.

(image via: Night Sky Hunter)

In the spectacular image above, the photographer used a 30-second exposure at 4:34am in the morning, the moon being nearly full. The bright star under the moonbow is the orange supergiant Arcturus.

Unearthly Rainbows

(image via: Utah Skies)

Are rainbows strictly a terrestrial phenomenon? No reason why they should be – the laws of physics (and optics) are universal after all. So far, however, the only off-earth rainbows we’ve glimpsed have come as the result of wishful thinking or through the visionary illustrations of science fiction artists. Pity… wouldn’t it be cool if the Bay of Rainbows on the Moon (above, top of image) actually had rainbows?

(image via: NASA)

A rainbow on Saturn? Not quite – what appears to be a rainbow on the brightest part of Saturn’s magnificent rings is merely an “artifact” of the Cassini spacecraft’s imaging system.

(image via: Celestial Matters)

There is one place in the vicinity of Saturn where rainbows of the classic variety may be found, however, and that is on it’s largest moon, Titan. Observations have confirmed the existence of liquid in the form of methane rain and lakes on the cloudy, chilly moon though a methane rainbow might look a little different than the ones we know here on Earth. Someday, someone will be the first to see one!

(image via: Kansasphoto)

Truly rainbows have earned their reputation for being the crowning touch for any scene of natural beauty. Like snowflakes, every rainbow is unique and one-of-a-kind… and somewhat sadly, all too temporary. Perhaps the true pot of gold is to be found not at the end of the rainbow, but by having the privilege to view one from the beginning.

The Elusive Beauty of Lunar Rainbows

courtesy of Environmental Graffiti

Moonbow, Yosemite Lower Falls, Photo: Meng Tang

When the moon is near its fullest, and barely a cloud veils its face, certain locations on earth treat observers to the scarcely seen light phenomenon known as the lunar rainbow, or moonbow. Like daytime-occurring rainbows, moonbows are formed when rays of light bounce off water droplets suspended in the air – the vapour of a raincloud, say, or the spray from a thundering waterfall – though of course they are caused not by the direct light of the sun but by that which is reflected by the moon.

Driving through a night time archway: Moonbow on Fraser Island, Australia

Photo: G a r r y

Like their diurnal counterparts, moonbows always appear in the part of the sky opposite the celestial body that provides their light source, with the moon thus positioned behind the viewer. Except for those lunar bows whose medium is the mist of waterfalls, a rare combination of a low moon and a dark sky are needed to create this spectacular sight – not to mention rainfall up ahead.

Gold at the end of the moonbow: Captured over the Pacific Ocean in Tahiti

Photo: Pierre Lessage

Even with the moon at its brightest, moonbows are faint compared to typical rainbows due to the low quantity of light shone down by our only satellite. The glow is too weak to stimulate the colour receptors of the naked eye – meaning moonbows are often seen as being white – so it’s lucky long-exposure photography has stepped in, enabling us to see all the colours of the moonbow.

Misty moonbow: Dark and drizzly but notice the glowing grass in the foreground

Photo: Jo Bradford

Photographers have written reams about how best to capture this singular phenomenon. Tips include the use of a tripod, switching to manual focus, and bracketing exposure time to avoid a white blur, with looking for your shadow, and starting with a fresh roll of film and batteries among other pointers mentioned.

African moonbow: Lunar rainbow taken from the Zambian side of Victoria Falls

Photo: Calvin Bradshaw

Of course, you’ve also got to know where to find moonbows, since there are only a small number of places in the world where they regularly materialise. Victoria Falls on the border between Zambia and Zimbabwe, Cumberland Falls in Kentucky, Yosemite Falls in California, and Waimea on Hawaii are some of the best known.

Perfect arc: A stunning arched moonbow formed over Hawaii

Photo: Hawaii Preparatory Observatory

Harvest moonbow: A beautiful curve of colours over Cumberland Falls, USA

Photo: Bryce Fields

Dreamy scene: Water spray from Yosemite Falls brightly coloured by a moonbow

Photo: satosphere

Yosemite is such a hotspot for viewing moonbows that a team of astronomers at Texas State University were inspired to develop a computer programme which can reliably predict when moonbows are likely to appear at the falls of America’s famous national park – other factors such as a clear sky permitting.

Wash of colour: Another moonbow forming beneath Lower Yosemite Falls

Photo: Ambitious Wench

People have been watching moonbows since Aristotle’s day – and doubtless long before – but this research is the first time anyone has calculated precise dates and times for their appearance. Now it is hoped we may better appreciate this incredible yet elusive natural wonder.

Picture this: Star trails get in on the act in our final glorious shot from Yosemite

Photo: SocalJC

Let’s leave with the words of naturalist and pioneering environmentalist John Muir in an extract from his 1912 book, The Yosemite, which describes the great man’s experience of a moonbow: “This grand arc of color, glowing in mild, shapely beauty in so weird and huge a chamber of night shadows, and amid the rush and roar and tumultuous dashing of this thunder-voiced fall, is one of the most impressive and most cheering of all the blessed mountain evangels.”

Sources: 1, 2, 3, 4