Have you ever been hiking along a misty trail and suddenly been overcome by the unsettling sensation that you’re not alone? Well, you’re not alone! For centuries now, hikers have been describing mysterious phenomena where it appears that the silhouette of a very large stranger is standing on the opposite hillside, silently watching them. Bigfoot? The very thought of it is enough to make you wish you’d gone for a lighter pair of hiking boots so you could scurry down the hill pronto, but if it happens to you, don’t be too alarmed – there’s (probably) a perfectly rational explanation for this ominous occurrence.
Though the apparition of a shadowy figure in the mist is probably as old as, well, mist itself, it was first recorded by a German scientist of the name Johann Silberschlag back in 1780. Silberschlag coined the term 'Brocken Spectre' to describe the phantom figure, having experienced it firsthand in the notoriously foggy Brocken, the tallest back in the Harz Mountain Range of northern Germany. The Brocken is not a remarkably tall mountain, standing as it does at a humble 3,743ft, but it possesses a rather unique microclimate which resembles mountains closer to 6,600ft (think Mount Washington in New Hampshire).
This microclimate is almost always host to mist and fog, which cloaks the mountain for some 300 days a year, and the mean annual temperature here is just above freezing, at 37.2°F. Consequently, the Brocken has long figured in eerie folklore and visions of shadowy figures are a common sight here, though you can see them on any mountain with fog and mist.
What is a Brocken Spectre?
So what exactly causes this unearthly presence? According to the UK’s Met Office, a Brocken Spectre, also known as a Brocken Bow, or Mountain Spectre, is simply your own shadow. If you’re standing on a misty hillside with the sun behind you, it can throw your shadow onto the mist and create the illusion of a very large figure standing some distance away. The image may be amplified by the addition of a rainbow-colored halo around the figure, and the figure may appear to be moving – however, rest assured that it’s just the clouds that are shifting.
In his 1966 autobiography, the explorer Eric Shipton wrote of seeing a Brocken Spectre on Mountain Kenya: “The rays of the setting sun broke through and, in the east, sharply defined, a great circle of rainbow colours framed our own silhouettes.” Brocken Spectres have also made many appearances in popular culture, including literary works by Charles Dickens (Little Dorrit), CS Lewis (The Problem of Pain) and, perhaps unsurprisingly, Lewis Carroll (Phantasmagoria).
And there you have it. If you see a monstrous umbrous figure on the opposite side of the hill when you’re hiking in the fog, it’s probably an optical illusion and you can reach for your camera and not your bear spray (we don't know if that works on Sasquatch anyway).
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Julia Clarke is a staff writer for Advnture.com and the author of the book Restorative Yoga for Beginners. She loves to explore mountains on foot, bike, skis and belay and then recover on the the yoga mat. Julia graduated with a degree in journalism in 2004 and spent eight years working as a radio presenter in Kansas City, Vermont, Boston and New York City before discovering the joys of the Rocky Mountains. She then detoured west to Colorado and enjoyed 11 years teaching yoga in Vail before returning to her hometown of Glasgow, Scotland in 2020 to focus on family and writing.