Skip to content Skip to sidebar Skip to footer


10 Strange Optical Illusions & Atmospheric Phenomena (& Where to See Them)
By Debra Kelly,
Urban Ghosts Media, 23 March 2016.

Sometimes, we get so caught up in the day-to-day grind that we forget how amazing - and at times mysterious and terrifying - the world around us really is. It’s easy to take nature for granted, despite its many unfathomable wonders. In this article, we decided to explore a selection of the most compelling and occasionally haunting optical illusions and atmospheric phenomena that the natural world has to offer, as well as the best places around the globe to experience nature’s most colourful, surreal displays.

1. Brocken Spectre Illusion, Harz Mountains, Germany

Image: via Wikipedia; the haunting optical illusion known as Brocken spectre.

The Brocken spectre illusion is named for a single peak in Germany’s Harz Mountains. Even though the spectre can appear anywhere - even out the window of a plane - when the conditions are right, it was here that it was first documented and officially described in 1780.

The spectre is an incredibly eerie phenomenon, occurring when the sun is positioned behind a person looking downwards into fog or mist. The shadow cast is elongated and eerily magnified, usually surrounded by a rainbow, and sometimes presenting a terrifying, otherworldly figure. If there’s even a tiny rustle of wind, the figure can appear to move on its own, and with the Harz Mountains shrouded in clouds and mist for an average of 300 days every year, they’re the ideal place to witness the strange phenomenon.

It’s no wonder, then, that the optical illusion known as the Brocken spectre has been at the heart of countless fairy tales and legends of witchcraft and sorcery that swirl around the mountains. Literature buffs will recognize the Brocken spectre as the site of Goethe’s Faustian revels, and it’s still known as a place where witches gather. April 30 marks the feast of Saint Walpurga, an event observed throughout western and northern Europe even today, usually with bonfires, costumes, kissing under the cherry trees and dancing.

2. Fata Morgana, Strait of Messina, Italy

Image: via Wikipedia; a Fata Morgana is a complex superior mirage.

Countless people over the centuries have reported a strange optical phenomenon off the coast of Sicily, and Wired shares an account from Father Domenico Giardina in 1643. The priest wrote that he had seen something miraculous, an entire city floating in the air over the ocean. He recounted, “[it was] so measureless and so splendid, so adorned with magnificent buildings, all of which was found on the base of a luminous crystal.” As he watched, though, something terrible happened: the city was apparently engulfed by the chaos of war, and disappeared.

What Giardini had seen was a Fata Morgana, a complicated optical illusion that had been freaking people out for centuries. He is credited as being one of the first people to try and understand the science behind the mysterious atmospheric phenomenon, which had previously been attributed to everyone from God to necromancers (it’s even named after the Arthurian legend’s Morgan le Fay).

Giardina thought that the high mineral and salt content in the waters of the strait evaporated, formed clouds, and created a sort of mirror that cast the reflection of the nearby city onto the horizon. And he was surprisingly close.

When the sun heats up the atmosphere to a temperature higher than the air just above a cooler ocean, the temperature difference causes light to refract at the intersection. The human brain doesn’t realize this, though, and when the curve of the earth makes the landscape ever more complicated, our brains fill in the blanks with what becomes a Fata Morgana, an incredible and at times frightening mirage.

3. Catatumbo Lightning, Venezuela

Image: Thechemicalengineer; haunting atmospheric phenomena.

If you love thunder and lightning, head to a particular place in Venezuela that averages about 260 stormy nights a year. The peak season for this tumult is October, when there’s an average of 28 lightning flashes every minute during nightly storms. The atmospheric phenomenon lights up the skies over Lake Maracaibo and the Catatumbo River…but no one knows why exactly.

The current theory is that there’s something about the way the wind sweeps across the region’s peculiar topography that creates a sort of hot spot for temperature fluctuations and, in turn, lightning. It’s been suggested that there are some sort of mineral deposits in the area that make the air super-conductive, although no one’s been able to prove conclusively what turns the night skies over the lake into such a spectacular light show.

And it’s a light show that’s been going on for centuries. The earliest reference to Catatumbo Lightning comes in the 1597 poem La Dragontea, and the atmospheric phenomenon was commonly used by sailors as a navigation tool. Visible for around 250 miles, the lightning storm suddenly ceased for several months in 2010 - apparently corresponding with the area’s drought conditions.

4. Lluvia de Peces (Rain of Fish), Honduras

Image: Ana Perugini; the truly bizarre ‘Rain of Fish’, illustration purposes only.

Every year in either May or June, the little town of Yoro in Honduras is subjected to a truly bizarre phenomenon. One day, sometime during those two months, a powerful storm will roll through town. Once the weather clears and people re-emerge from their homes, they find the visitors the rains have left behind. Fish. Lots and lots of fish.

And again, no one’s entirely sure why. Rains of weird things - like Kentucky’s notorious meat shower - aren’t unheard of, but this one has been happening regularly since the 1800s. Atlas Obscura reports that a team from National Geographic witnessed the storms in 1970, and even then failed to walk away with proof as to what was going on. They did, however, examine the fish to find that they were all blind.

And that fact has led to another theory that suggests the fish aren’t falling from the sky with the rain, but that they’re emerging from under the ground. They likely live in underground rivers, and the heavy rains force them up and onto the streets. The traditional explanation is much more mystical, and the annual festival celebrates the rain of fish that first came from God, as a priest prayed for relief from famine and hunger.

5. Watermelon Snow, Sierra Nevadas, United States

Image: Peretz Partensky; watermelon snow, caused by algae.

We all know better than to eat yellow snow, and we shouldn’t eat the rarer pink stuff, either. Snow is surprisingly packed with all manner of things, including 60 different types of algae - and those are the ones we know about. Scientific American reports that the most common is Chlamydomonas nivalis, which is - weirdly - a type of green algae that turns snow pink when it grows.

Certain conditions are perfect for the growth of these tiny organisms. They thrive at high altitudes (usually between 10,000 and 12,000 ft) beneath sunny skies where the temperature never gets too hot - conditions like those found in the mountains of the Sierra Nevadas. When packed snow doesn’t melt in the sun. algae thrives, and the snow doesn’t just turn pink, but it gives off a smell that’s been described as that of a watermelon.

The first records we have of watermelon snow come from ancient Greece and the writings of Aristotle. He didn’t give an explanation, but for centuries it was thought that minerals were leaching into the powder to give it a weird, pink colour. It wasn’t until 1818 that Scottish botanist Robert Brown came up with the idea that the colour had plant-based roots.

6. Dirty Thunderstorms, Sakurajima, Japan

Image: Oliver Spalt; weird weather phenomenon known as a dirty thunderstorm.

Dirty thunderstorms happen all over the world, but BBC Earth suggests that one of the best places to see this captivating atmospheric phenomenon is at the Sakurajima volcano in Japan. A dirty thunderstorm requires specific - and terrifying - conditions to occur. It’s a type of storm that only happens over an active and erupting volcano, and the lightning from the storm comes from the clouds that gather over the mouth.

Rock fragments, dust and ash are hurled into the air and when they collide, they produce a static charge. It’s the same static charges that produce regular lightning, only these are happening with rock particles instead of ice. In addition to Japan’s Sakurajima, the phenomenon has also been seen over an erupting Mount Etna, as well as Iceland’s Eyjafjallajokull volcano.

In 2015, German film-maker Marc Szeglat described everything that went into getting some absolutely stunning photos of the phenomenon, including fighting shockwaves so strong that they threatened to knock over his equipment.

7. Naga Fireballs, Mekong River, Thailand

Image: Tuohirulla; an artist’s impression of the folkloric Will-o’-the-Wisp.

For centuries, the Mekong River between Ban Muang to Bung Kan has been the scene of an incredible atmospheric phenomenon: the Naga fireballs. At any time during the year (but most frequently in late October or early November), fireballs can be seen rising from the river’s surface and disappearing into the night sky. The annual Phaya Naga festival (which coincides with a major Buddhist holiday) celebrates the mythology of the mysterious lights, which are said to be the flames exhaled by the the underworld’s serpent king, Phaya Naga.

The frequency of the Naga fireballs vary from year to year; in 2004 they hardly appeared at all, but 2001 reportedly saw more than 3,000 fireballs dancing along the Mekong River and into the night sky. The festival as it’s celebrated today is a relatively recent event, dating back only to the 1990s. Records of the Naga fireballs go back centuries, however, with temple records mentioning ancient appearances of the mysterious atmospheric phenomenon long ago.

That hasn’t stopped skeptics from trying to debunk the Naga fireballs as anything from fireworks to tracer bullets. Scientists suggest a rational explanation for the strange phenomenon that likely involves the release of gas that ignites due to a chemical reaction with other gases given off by decaying matter in the river. It’s also been suggested that the Naga fireballs seen today - high, fast-rising flames - aren’t the same as the less impressive lights recorded earlier - although any suggestion that it’s a hoax is met with staunch denial from believers.

8. The Hessdalen Lights, Hessdalen Valley, Norway

In 1981, strange lights started appearing over Norway’s Hessdalen Valley. The phenomena varied, sometimes a series of bluish-white flashing lights, sometimes yellow-red, other times yellowish-white. Solid white lights have also been seen, sometimes ball-shaped, sometimes moving, sometimes stationary for up to an hour before moving off. The mysterious atmospheric phenomenon is most active during the winter months, usually between 9 pm and 1 am.

Not surprisingly, the weird lights have been the subject of all manner of UFO conspiracy theories. In 1998, Project Hessdalen was formed to try and analysis the lights scientifically to figure out what was behind them. There’s a host of more earthly explanations for the lights, including theories of solar activity, the interaction of charged particles, and even mini black holes. One scientist suggested that water freezing in and around the valley’s quartz deposits was causing an electric charge to build up as the water expanded and moved the quartz, which jumped into the atmosphere and caused the lights.

One hypothesis in particular is pretty terrifying, and it involves radiation emanating from the nearby rocks. Researchers found rocks giving off radon, which rides into the air on the back of dust particles. When the radon decays, it emits alpha particles that may be forming plasma, which, in turn, creates coulomb crystals that generate the eerie light.

9. Moonbows, the Cloud Forests of Costa Rica

Image: CalvinBradshaw; moonbows, an almost-surreal atmospheric phenomenon.

Moonbows are also called lunar rainbows and white rainbows, and are usually incredibly faint. The phenomenon occurs when moonlight refracts through moisture in the air - the same way regular rainbows form, only at night. Because they’re so faint they’re hard to find, and our brains make it even more difficult. Human brains are creatures of habit, after all, and since we’re not used to detecting colours in the night sky we tend to filter out all but the brightest of them. We also tend to misinterpret some of the colours we do see, occasionally mistaking clouds of colours for a true moonbow.

They usually show up during a full moon, when the moon is at a low point in the sky, and when rain falls directly opposite the Earth’s satellite. One of the best places to see a moonbow (along with Yosemite Falls and Victoria Falls) is among the haunting cloud forests of Costa Rica, incredible nature reserves that are tropical or subtropical forests with 100 percent humidity. The humidity means that water droplets are constantly collecting in the air and on the surface of the forests in what’s called horizontal precipitation, and the presence of water in the air is what makes this beautiful atmospheric phenomena so common.

10. UFO Clouds, South Africa

Image: KSszilas; UFO clouds sweep across the mountains.

Technically they’re called lenticular clouds, but the more popular ‘UFO Clouds’ has an undeniable ring to it. At a glance, it’d be easy to mistake these low-lying clouds for alien craft gathering on the horizon, which is what makes them so cool.

The atmospheric conditions necessary for the formation of UFO clouds are particular, and require strong winds full of moisture to blow across rough, irregular terrain. The temperature also has to be right, allowing the winds to cool over the mountains and valleys. As the moisture cools it condenses into the saucer-shaped clouds.

Image: fdecomite; lenticular clouds are caused by a specific atmospheric phenomenon.

Cape Town, South Africa, is surrounded by water and mountains that make conditions perfect for the formation of lenticular clouds, and it’s not surprising that the stunning city in Western Cape was once a hotbed of UFO sightings. The clouds can form anywhere (even over flat land, if conditions are right) and aren’t always as well-formed as Cape Town’s characteristic UFO clouds. The strange atmospheric phenomenon is known to appear and then disappear quickly, as the same movement that creates the cloud often causes it to evaporate just as fast as it forms.

Top image: UFO clouds, a strange atmospheric phenomenon. Credit: Omnisource5.

[Source: Urban Ghosts Media. Edited.]