Rare 'frost beard' ice formation discovered by a hiker

The winter chill in early January surprised many across England this year. On January 11, 2025, a casual walk through the Devil’s Punch Bowl turned into a moment of astonishment for a local resident.

He spotted a curious formation that resembled fine strands of white hair wrapped around a twig, and he soon realized it was something quite special.

Fluffy, frozen cotton?

The walker, identified as the Reverend Jonny Scott from Godalming, initially saw what appeared to be fluffy cotton on a piece of wood. He was intrigued.

He wondered if it might be a strange fungus or just a bit of frosty residue that had collected on the bark. His interest grew when he recognized that the material was actually made of delicate ice fibers.

Experts have known about this unusual natural display for more than a century. In 1918, the phenomenon earned scientific attention for its striking appearance.

Scientists Dr. Christian Hofmann from the Institute of Applied Physics, Dr. Christian Mätzler from the Institute for Meteorology and Climate Research, and Dr. Gisela Preuss from Biogeosciences led a project in 2015 that clarified the precise cause of this unique formation.

They learned that a fungus named Exidiopsis effusa helps these icy filaments develop on rotting wood.

Nature’s artistry in rare weather

The Met Office states that hair ice, often called frost beard, only appears on damp, rotten branches of broadleaf trees.

Temperatures must hover below freezing at latitudes between 45°N and 55°N, which includes parts of Europe and North America.

Such narrow requirements explain why people so rarely witness these wispy ribbons of ice. Moisture in the wood meets just the right chill to create slender strands of around 0.01 millimeters (0.004 inches) thick.

Rev. Scott was thrilled when he realized he had encountered an extremely uncommon sight. “Nature never ceases to amaze me!” he exclaimed.

He carefully picked up the twig, puzzled by the sheer fragility of the ice. He recalled seeing “a twig that looked to be wrapped in cotton wool” or “perhaps a strange fungus,” but closer inspection proved it was crystal-like hairs of ice.

Fungal helper Exidiopsis effusa

Scientists looking at these formations discovered that the fungus maintains the ice structure by shaping water into threads along the wood’s surface.

During cold weather, water in the wood expands outward, and the fungus helps it freeze into smooth filaments, preventing the ice from clumping.

The strands stand firm until temperatures rise above freezing, or direct sunlight hits them, which causes them to vanish in a matter of moments.

The existence of hair ice was first documented over 100 years ago, and several theories arose to explain how these slender filaments formed. Some early researchers suspected bacterial processes.

Others suggested peculiar chemical reactions in rotting wood. The 2015 research by Hofmann, Mätzler, and Preuss confirmed that Exidiopsis effusa is essential in shaping the ice, which put long-standing debates to rest.

Moments of wonder

The Devil’s Punch Bowl, a vast natural amphitheater, has long been a favorite among local hikers seeking fresh air and scenic views. Running into hair ice enhances a simple stroll, turning it into something extraordinary.

Rev. Scott admitted he had never even heard of hair ice before, and he felt a bit of excitement to spot such a rare event by chance.

Once he returned to the car park and did a quick online search, he realized he had stumbled upon a fascinating natural curiosity.

Fragile beauty

These frozen fibers appear unexpectedly, almost like an artistic flourish designed by the cold. They are easily missed if you’re not paying attention.

Observers often find them on fallen branches scattered along woodland floors. Many folks walk right by without a second glance.

But for anyone who does pause to look, the sight can be quite memorable. Even though hair ice can arise in several places within the right latitudes, people rarely notice it.

And It doesn’t last long. A brief shift in temperature or a stray ray of sunshine is enough to melt the fragile ice.

Why does any of this matter?

The fleeting nature of hair ice heightens its appeal. For many, the momentary glimpse of these icy tresses symbolizes how rapidly beautiful things in the natural world can come and go.

It’s a reminder to stay curious, no matter how familiar a place might seem. Rev. Scott’s story highlights the potential rewards of keeping a watchful eye on the woods.

Research scientists, mycologists, and weather experts continue to investigate subtle interactions between fungi and their surroundings. There’s still much to learn about the microscopic processes that lead to the formation of hair ice.

Each small piece of understanding adds to a broader view of how living organisms and seasonal conditions overlap in unexpected ways.

New perspective

It’s easy to overlook delicate sights like these when you think you’ve seen it all. Sometimes, the simplest items – a fallen twig, a chilly breeze – combine to create something that sparks genuine awe.

Rev. Scott encountered hair ice on a routine stroll, and his discovery brought attention to a phenomenon that deserves more admiration from nature lovers.

The study is published in Biogeosciences.

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