A childhood memory of fog haunts me. I was six or seven and, with my two bigger sisters, had climbed the hill from our village and walked over the fields to Wyatt’s Farm in Somerset to buy fresh corn-on-the-cob.
It was a late summer’s day and if I’d been more knowledgeable, I might have worried that the edges of the world were already hazy. By the time we were making the return trip, a thick fog had descended, the horizon vanished and we could only see a short way ahead. I still remember the seemingly endless panicky search for familiar stiles and gates in a wraith world.
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Fog in popular culture
I’m not alone in thinking of fog as a frightening presence. Folklore, books and films regularly depict fog as a lurking menace. It limits vision, dims perception and hides the actions and motives of ne’er-do-wells. The Brenin Llwyd – the Grey King – of Welsh legend is a baleful mountain spirit that emerges in the mist to prey on travellers and children. In the most famous Sherlock Holmes story, The Hound of the Baskervilles, fog is a central character, a creeping blanket of fear over Dartmoor that thwarts even the great detective. Back in the real world, as any motorist knows, fog can be truly dangerous when you’re out on the road, especially at night.
Chasing fog
So, for many of us, fog is an unsettling phenomenon. But not for all, as I found recently, when I made a podcast with photographer and author Laura Pashby. In her new book, Chasing Fog, Laura experiences connection, beauty and a deep sense of self within fog and its even more ethereal twin, mist. I planned a walk with Laura at Uley Bury, an Iron-Age hillfort high on the Cotswold escarpment in Gloucestershire.
On the day we meet, frustratingly it’s gloriously sunny after a week of fog. The long ramparts of the hillfort jut like a ship’s prow but in the vales below, tendrils of mist endure. “It’s magical to be here – but even more so in the fog,” says Laura. “When a landscape is completely subsumed by the fog, you suddenly feel as if you could be not just in any place but in any time. It could be any point in any century and I don’t think this place would look particularly different to how it was when the Iron-Age people were here.”
Laura opens her book with a foggy encounter at the hillfort, which turned out to be an epiphany for her: “A rising fog crept up from the River Severn valley below, up and over the hill above us, enveloping the woods as we climbed… The woods were different, beautiful but also potent and uncanny. I was sharply aware of the hillfort, invisible in the cloud. Now I could no longer see its presence and a sudden vision of the curled figure of a crouched burial found within, loomed over me. All visible traces of the 21st century had faded away.”
For Laura, fog and mist enable this imaginative connection to earlier times and peoples. “In folklore, there’s often a sense of fog as a kind of portal. If you step into the fog, when you come out of it you might be somewhere completely different.” It’s a beguiling but still unsettling idea.
Laura explains more about fog’s transformative powers: “I feel different to how I feel the rest of the time. It’s something to do with being completely surrounded and everywhere being transformed. My world shrinks to my immediate physical vicinity. I can’t see a long way and in the same way I often lose visibility of the current moment in time and I’m much more in the landscape. I suppose ‘meditative’ is probably how I describe that. It’s almost a kind of mindfulness.”
Laura embraces the sensory changes that others might find disconcerting. “Even though you don’t lose your sense of vision in the fog, it’s very different,” Laura says, “and as a result of that my other senses tune in more acutely, particularly to the sounds of birds. They sound different.” As someone who spends more than his fair share of time listening to birdsong, I assume fog muffles their voices, but Laura disagrees. “I think they sound louder, and I can’t work out whether that’s because the fog encourages them to make louder sounds or it’s just because losing your other senses means that you hear more clearly.” I realise that I cannot remember hearing birds in fog, perhaps because fog is more prevalent in the cooler months when birds sing less. I make a mental note to get out into springtime fog and test the thesis.
By this time, we have followed the outer rampart of the hillfort to its far end, where it hangs high over a valley and, more distantly, the town of Dursley. In between, is solitary Downham Hill, for which Laura has an excellent folklore tale of a traveller lost on a foggy night. Our hero finds shelter in an inn on the hilltop only to discover next morning, when the fog has cleared and he has long departed, that there never was an inn and that he has had a dangerous encounter with the fog’s fairy folk.
What is fog?
For all this talk of fog’s power to transform senses, place and time, we haven’t yet discussed what it actually is. Fog occurs when moisture in the air condenses as air interacts with the land. In a sense it is low-lying cloud, but it can form due to a range of conditions. In Chasing Fog, Laura meets a range of different fogs around the UK and Europe. But here where the Cotswolds meets the Severn Valley, she explains that fog usually occurs when cold dense air settles and condenses in the valley bottoms, with warmer air passing above, trapping it there. This is called valley fog and it can last for days. Hill fog or upslope fog occurs when wind blows air up a slope and it cools and condenses, which would explain the fog on Uley Bury.
Sea fog, or advection fog, is caused by warm air moving over a cold surface or sea, where it condenses into fog and may then be blown inland. There is also evaporation fog, which occurs when cold air passes over warmer water or marshland and the evaporating water condenses into fog. Finally, radiation fog is a feature of cold winter nights when the land cools overnight and therefore cools the air layer immediately above it, creating fog or mist. This is usually quickly dispersed as the sun rises and warms the land.
And what’s the difference between fog and mist?
“Quite unpoetically it’s just a matter of degrees of visibility. You can see further in the mist than you can in the fog,” explains Laura. We joke that fog is heavy mist and mist is light fog. Lighter still is haze, which is more likely caused by pollution, especially smoke from bonfires or domestic wood fires.
Laura’s book is called Chasing Fog for a reason. Within it, we join her on quests to find her ethereal friend from Cornwall to the Fens and from Dartmoor to the sea fogs of Scotland’s east coast. She explores the mood-shifting Thames Estuary and, most memorably, ends at that city of water, fog and mist, Venice.
Is fog disappearing?
While fog can be predicted through weather forecasts, it is elusive and is becoming more so. Laura has discovered that her own diary records tally with those of climate scientists in that fog is occurring less frequently, and this is very likely due to climate change. From her notes, Laura has found a 50% drop in fog events, especially sea fog. The problem here is that as oceans warm, the conditions for sea fog – which requires a cold-water surface to form – are less prevalent. Fog is vanishing.
Why does it matter?
Apart from the loss of something eerily magical from our lives, the growing absence of fog could impact on habitats and wildlife. In her book, Laura visits the wet woodlands – rainforests – of Dartmoor, such as Wistman’s Wood, and similar habitats on the Beara Peninsula on Ireland’s south coast. In these woods, there are unique mosses, ferns and lichens that provide so many micro-habitats and are nurtured by moisture in the air. “There were times when I’d be in these landscapes, and it wasn’t foggy, but I could sort of see that fog is there, and it’s almost been absorbed into the landscape, and it will come back.” Beara in particular is dependent on sea fogs rolling off the Atlantic – if these were to vanish, the woodlands would dry up and much unique wildlife would vanish.
Laura is still chasing fog, and collecting sightings and records from her vast numbers of followers on Instagram. You can enjoy her adventures and share thoughts on @circleofpines. “My friends and my family will send me a message whenever it’s foggy!” You can also listen to Laura's Plodcast episode above.
As I write this, from a farm on the edge of Bannau Brycheiniog, a cold valley fog has descended and I have taken the opportunity to experience the murky landscape with new eyes – and ears. Perhaps, with Laura’s words fresh in my mind, that childhood fear can be put to bed. Incidentally, it was my big brave sisters who finally found a friendly stile, led me out of the fog and down the hill to home and a supper of fresh, if hard-won, sweetcorn.
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Main image: the valleys of Whaley Bridge and Chapel-en-le-Frith in Derbyshire. Credit: Getty
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