A local ‘storyteller’ performed in Kiruna library this week. A stranger approached him in the street and said, ‘Have you ever been to Valluskoski?’ He replied that no, he hadn’t. ‘Pity,’ said the man, and walked away.

Some things are just too hard to describe – you have to be there. Nacreous clouds for instance.

These ‘mother of pearl’ clouds up in the stratosphere are very bright, wavy, multi-coloured patches in the sky. At new year we got talking to some visitors out on the street and a woman there was really keen to tell us about them. Yes yes, I assured her, we had seen them too. But she just had to show us all the pictures she had on her phone, and tell us what the clouds were. Yes, I said, they really are wonderful. But she still wasn’t absolutely sure – had we really seen them, the same ones as her? It’s as if, once they’re gone, they’re just unbelievable.

They’re so high up they don’t appear to move sideways much, though they slowly spread and shrink into shapes that merge and part over a few hours. A bit like a lava lamp, only slower, and more colourful. Or maybe, not at all like a lava lamp.

The sky can look like it’s broken and through the hole you see colours and shapes. This is indeed what has happened, since this is where the ozone layer is much thinner than it should be.

They’re visible around dawn and dusk, and as these periods are very long this far north we have more chance of seeing them. They’re formed by winds flowing over mountain tops – that’s what creates the wavy pattern. It has to be cold too, very cold.

They might look to some like UFOs – they often have a saucer shape, and they look unnaturally, eerily bright. Long after the sun has set they are beacons of light in the sky. Your brain can’t quite accept a cloud as source of light rather than something that dims the light.

I’ve been enthusing over these light effects for years and claiming they’re just as amazing as the northern lights, but they’re hard to describe, and photos of them never do them justice.

Have you ever seen nacreous clouds? You haven’t? Oh that is a pity.