We all know the colorful arc of a rainbow that follows a storm. But nature paints the sky with a diversity of rainbows beyond the common type. Some of the rarest and most mystical include moonbows, twinned bows, fogbows and circular rainbows. Spotting these ephemeral phenomena feels like discovering hidden secrets of the natural world.
Moonbows – Rainbows of the Night
Imagine seeing a rainbow at night. Enter the moonbow – a rainbow created by moonlight rather than direct sunlight. Also called a lunar rainbow, moonbows form when the moon is bright (near full) and low in the sky. Light enters raindrops, refracting and reflecting to split white moonlight into colors.
Moonbows tend to appear white to the naked eye. With the moon 400,000 times dimmer than the sun, a moonbow’s colors are too faint for our eyes to discern – though some observers report hues at peak brightness.
Nonetheless, moonbows are exceptionally rare celestial events. They require ideal alignments of bright moonlight, falling rain, darkness, and viewing angle. If you’re lucky enough to catch one, it looks like a ghostly white arc low in the night sky. Some cultures considered lunar rainbows to have mystical significance.
One of the best places to see a moonbow is over the waterfalls of Victoria Falls in Zambia. Best time is during the rainy season, where just after sunset you can witness one of the most breathtaking rainbows ever (see first picture above).
Twinned Rainbows – Double the Beauty
taken by Michael Nichols for National Geographic in Samburu National Park in Kenya.
Imagine not one but two rainbows sharing the same base – a “twinned” rainbow. This phenomenon occurs when unique conditions create two separate rainbows side-by-side.
Scientists believe twinned bows likely form when two rain showers overlap, each with different water droplet sizes. The variety in droplet size splits sunlight into two distinct rainbows rather than one. While regular double rainbows stack atop each other, twinned bows run parallel, making the sight even more exceptional.
The perfect storm ingredients make twinned rainbows exceptionally uncommon. But for lucky observers, they double the rainbow beauty. The twin bows seem to magnify nature’s kaleidoscopic artistry.
Fogbows – Rainbows of the Fog
Fogbows reveal rainbow colors within mist and fog. To form, suspended water droplets in fog refract and reflect light like raindrops. But because fogbows lack the brilliance of direct sunshine, their dim colors blend into white.
Rannoch Moor in the west of Scotland by photographer Melvin Nicholson
These elusive “ghost rainbows” occur when the sun peeks through thin fog at a low angle, usually around sunrise and sunset. Fogbows also appear brighter from elevated viewpoints above the fog layer. The delicate bows showcase light’s artistry using mist as a canvas.
Circular Rainbows – Rainbows Unbound
Rainbows are actually full circles – we normally only see arches. But when viewed from high altitudes like mountain peaks or airplanes, rainbows can reveal their circular entirety from horizon to horizon.
On the ground, our view of the complete rainbow circle gets blocked by the landscape and horizon. And the sun needs to be at just the right angle for a circular rainbow to appear. But when conditions align, viewers can see rainbows in their full 360° circular glory.
These complete rainbow rings are miraculous reminders that the natural world contains unseen wonders for those bold enough to alter their perspective. Nature reveals its secrets to the curious.
Appreciating Nature’s Artistry
Part of the allure of rare rainbows is how unexpectedly they materialize, like fleeting works of art. A moonbow at midnight, a pair of rainbow twins, or a rainbow hovering in the fog – these marvels showcase nature’s creative spirit.
Spurred by science but shrouded in serendipity, rainbows retain their sense of wonder and mystique. Their splendor is amplified by how rarely we encounter special types like lunar bows and rainbow circles. But chance sightings make them all the more treasured.
So next time you spot any rainbow, consider yourself lucky to witness nature’s paintbrush at work. A rainbow’s beauty stems from the transient nature of its creation – never the same twice. Nature designs ephemeral, one-of-a-kind masterpieces if we keep our eyes to the skies. The next rainbow might just be a rare treat waiting to be discovered.
Additional Facts
9 Hours
In 2017, a rainbow was observed for 8 hours and 58 minutes over the Chinese Culture University in Taipei, Taiwan, setting a new record for the longest observable rainbow. The previous record was a 6-hour rainbow witnessed in Sheffield, England in 1994. The Taiwan rainbow, visible from dawn until nearly 4pm, demonstrated these fleeting meteorological phenomena can sometimes last far longer under the right conditions.
Eye of the Beholder
Rainbows have no physical form – they are optical illusions that vary based on the viewer’s perspective. Two people standing side-by-side will observe slightly different rainbow shapes, arcs, and color band widths based on their distinct vantage points. The ephemeral nature of rainbows stems from how they appear unique to every individual eye.
Path of the Gods
In Greek mythology, the goddess Iris personified the rainbow. Depicted taking rainbow form in art, she used a pitcher to collect water for clouds, creating a rainbow bridge from Mount Olympus to Earth. Her rainbow linked the realm of gods with mortals below.
