walkhighlands


Nacreous clouds – better than Photoshop!

Ben DolphinColour can be in short supply during the average Scottish winter. Whether it’s due to low cloud, mist or rain, or invariably all three at the same time, we spend much of the winter under a blanket of grey that drains anything bright and sharp from the landscape. Ours is a muted world made of different hues of grey, brown and green.

This inevitably means that when something colourful does finally come along it stands out with all the subtlety of a nuclear explosion. Waking up after weeks of dreichness to find a sparkling blue sky in the morning is like finding yourself in a Technicolor dreamworld after living your life in black and white. Yes, that’s right, living in Scotland is like being Dorothy in the Wizard of Oz.

Not that we get whisked off to Oz very often, mind. But still we live in hope, stubbornly clinging on to the shred of optimism that tells us there has to be a pay off at some point, and that we will ultimately be rewarded for our patience. If only the clouds could part and a bit of sunshine could shine through! That’s all we want!

Nacreous clouds over Fife

Nacreous clouds over Fife

I think, therefore, we all went a bit giddy when at the start of February, as the clouds parted for the first time in weeks, a phenomenon with more colour than a Dulux advert appeared from the gloom.

The curtain goes up

On 1st February I was at home in Fife, staring out the window as Storm Henry battered the Lomond Hills. There had already been a few sightings of this striking phenomenon in the preceding days up in Aberdeenshire so I’d been on the lookout for any clear views skyward since then, as I’d never seen it before. But low cloud had menaced the hills all afternoon and snow showers rattled through on the horizontal. It was bleak.

And then, just as the sun was supposedly setting, the clouds in the eastern sky parted slightly. I stepped outside to get a clearer look….but what would I see? Though I’d seen photos of these things before, you never really know just how representative such images are of the reality. Have the photos been adjusted? The contrast and saturation exaggerated? Has the photographer used a weird app or filter?

The pictures I’d seen certainly seemed unreal, or perhaps hyper-real. Surely the phenomenon couldn’t be THAT obvious in the sky, could it?

In a word…..yes.

At first it was partly obscured by gloomy clouds lower down but there was no mistaking the range of colours. Up there through the hole in the low cloud, extremely high in the sky was what can only be described as a ribbon of iridescence. As though someone had drawn a rainbow using oil paints and then tilted the canvas to make the colours run into one another.

The first fleeting glimpse

The first fleeting glimpse

I was expecting to see it but I was taken aback at just how iridescent these things were. Most of us will have seen localised iridescence on the fringes of very high cirrus clouds before, indeed I wrote about them in my very first article for Walkhighlands. But never in my life have I seen iridescence as extensive and colourful as this.

But it was fleeting. No sooner had my eyes accustomed to the contrast in the sky a huge anvil-shaped cloud closed the hole, and darkness returned as the house was engulfed in a blizzard. When it started to brighten up again after the shower had passed, the lingering daylight had been replaced by a bright twilight that bathed the landscape in a weird otherworldly glow. Gold tinged with pink.

As the last of the low cloud pulled away it slowly revealed the full extent and magnificence of what was going on above. It was like the curtain going up on a theatrical show, teasing with a gradual reveal. And oh my word, what a show it turned out to be!

Sharper, clearer and much more extensive than before. the weirdest clouds you’ve ever seen seemed to fill the sky. And writing now, a week or so after the event I still find it hard to describe them.

They weren’t puffy or blanket-like, nor were they grey or white. Every conceivable colour was up there, cast in the most peculiar shapes. They were more like lenticular clouds – smooth sided, flat and seemingly two-dimensional, but with strange angular protrusions. And yet some weren’t angular at all, instead they were almost wispy like great waves in the sky.

As the sun sank lower the colours changed. They got richer, and the area of sky they were in turned the weirdest pink colour. It was like someone’s art installation.

I’d NEVER seen anything quite like this

I’d NEVER seen anything quite like this

What on earth was I looking at? I’m well used to standing humbled before Nature, marvelling at the beauty and complexity of it all but this was as baffling as it was beguiling.

I knew it was caused by ice particles but that didn’t make watching it any less mesmerising or remarkable. In fact it was so mesmerising I quite forgot how cold I was, standing there in a freezing gale force wind.

I hastily posted a photo on Twitter and tweeted ‘IF YOU’RE IN FIFE LOOK EAST!!!’. I had no idea how widely it could be seen but this was something that HAD to be shared. Soon my Twitter feed was full of similar photos from all across Central Scotland. Accompanying the photos was the burning question on everyone’s fingertips:

WHAT IS IT!?

NACREOUS CLOUDS

The word nacreous (‘na’ is pronounced ‘nay’) derives itself from ‘nacre’, the name given to the oily sheen on the shells of sea creatures. We more commonly know it as ‘mother of pearl’. The clouds’ dazzling iridescence is produced by sunlight diffracting through (being scattered by) the tiny ice crystals of uniform size that make up the clouds.

They form at very high altitudes in the lower stratosphere, between 10 and 15 miles above us. Most of our weather occurs (and most of our clouds form) well below that in the ‘troposphere’ – the next layer down from the stratosphere and the lowest layer of our atmosphere. Unlike the troposphere, the stratosphere is very cold, very dry and therefore devoid of clouds.

But when rare moisture from below is driven upwards to that height it can form clouds….albeit ones made of ice particles. Apparently the stratosphere needs to be -78C or colder for nacreous clouds to form, which is common over the Arctic Circle during the winter but very rare over the UK.

An airliner below the beauty

An airliner below the beauty

However, the infamous polar vortex, that revolving body of very cold air that normally sits over the pole, shifted south over northwestern Europe during those first few days of February and that’s what allowed the clouds to form here. It has also been suggested that the turbulence produced by Storm Henry as it approached the UK was partly responsible for driving the essential moisture for the clouds’ formation upwards into the stratosphere in the first place.

Whatever the cause, their extreme height explains how they are seen over such a vast area. Their height is also responsible for their spectacular appearance, because before and during the sunrise, and during and after the sunset, the low sun strikes the clouds’ bases and illuminates them against what is an otherwise darkened sky. Full blown aurora aside, they are without doubt the most surreal and psychedelic thing you’re ever likely to see in the sky without ‘expanding your mind’ with all manner of questionable substances.

However, these dazzling visions do also have an unsettling relationship with ozone in our atmosphere. The ice particles that make up nacreous clouds provide a handy surface on which chemicals in the stratosphere can react with one another, the result of which is the destruction of ozone molecules and the thinning of the ozone layer.

Now, it’s important to note that the clouds themselves aren’t bad. They’re not dazzlingly iridescent because they’re full of chemicals, nor are they themselves the cause of ozone depletion. Rather, when they do appear they react adversely with the aerosols that we’ve pumped up into the atmosphere – chlorine and bromine. And for this reason a temporary thinning of the ozone layer occurred over the UK in early February.

This probably sounds quite alarming but don’t let it get in the way of appreciating them for what they are – natural, beautiful and awe-inspiring. Instead, perhaps choose to see them as a beautiful but stark reminder of the need to change our ways.

The curtain goes down

The next morning the clouds were back, this time in the west, and this second show was even more spectacular than the first. Vivid greens were visible and the sky was full of wispy iridescent waves and undulations, the soft pastel colours merging in and out of one another. It reminded me of the swirling background of Edvard Munch’s famous expressionist painting, The Scream.

Coupled with the deep red sun now rising from the Forth below, the scene before me was almost too enormous to appreciate.

The sun usually gets top billing during a sunrise….but on that morning it was sidelined.

The sun usually gets top billing during a sunrise….but on that morning it was sidelined.

How was it possible to cram so much beauty and magnificence into one person’s field of vision? It felt like we were being rewarded for all the suffering of the stormy winter. And I almost…..ALMOST…. forgave the Scottish weather if this was our payoff.

But by now I was addicted, so the next morning I set my alarm once again. Excitedly pulling the blinds open I saw plain blue sky and……no iridescence. The cold air had moved away. The curtain had come down.

Scotland shares a moment

Between 29th January and 2nd February 2016 the nacreous clouds were seen from Aberdeen to the Alps, witnessed by countless thousands of people as they travelled to and from their places of work on those mornings and evenings.

My other half was down in Kirkcaldy on that memorable evening and later told me how traffic on the A92 had slowed to 40mph as the spectacle unfolded above them. Certainly on Twitter there were photos of car tail-lights on rush hour roads – plenty of drivers no doubt sneaking a photo from behind their steering wheels.

I hasten to add that I don’t condone photography at the wheel, but when a natural spectacle is visible to so many people at one time, social media really comes into its own. I love the sense of togetherness it creates when an experience is being shared in real time, with the topic trending and actually prompting people to physically step outdoors to see what all the fuss is about.

Watching it all unfold online there was this wonderful sense that the whole country was sharing what can only be described as…..’a moment’….and it was heartening to see that something natural could still inspire such widespread awe and emotion.

As the curtain fell

As the curtain fell

But if half the population of Scotland hadn’t seen the sight for themselves, they might never have believed that the images that plastered their tablets and phones that day were real. And I wouldn’t have blamed them, for there’s a pervasive, defiant, arms-folded cynicism these days that greets most online photographs of amazing things.

‘PHOTOSHOPPED!’….goes out the cry. Fabricated.

But I honestly don’t think anyone could have made nacreous clouds up. I’m not sure anyone would think to fabricate them because, quite rightly, nobody would believe that something so unlikely could be so real. How wonderful therefore, that reality can still be stranger and infinitely more beautiful than fiction.

Nacreous clouds, ladies & gents. Better than Photoshop!

[Further information from NASA’s Arctic Ozone Watch data for 1st Feb. The blue area shows ozone depletion over the UK- ]




  • Accessories
  • Baselayers
  • Books
  • Camping
  • Footwear
  • Jackets
  • Rucksacks
  • Trousers
  • browse the
    ARCHIVES
  • 2017 (101)
  • 2016 (160)
  • 2015 (207)
  • 2014 (282)
  • 2013 (257)
  • 2012 (274)
  • 2011 (376)
  • 2010 (274)
  • 2009 (126)
  • 2008 (77)
  • Walking can be dangerous and is done entirely at your own risk. Information is provided free of charge; it is each walker's responsibility to check it and navigate using a map and compass.