As we did not observe the cloud ourselves and are only seeing the pictures, it’s not possible to be 100% certain, however it is most likely that these are nacreous clouds, also known as mother of pearl clouds.
This eye-catching cloud is rarely seen, and has only been sighted in polar regions (such as Scotland and Norway) in the winter months, especially when there is a low over northern Scandinavia with a strong west/north-westerly wind blowing over Scotland. They only form in the lower stratosphere – around 15 miles up – when temperatures here are below -78 °C.
Although nacreous clouds are brightest when the sun is just below the horizon, illuminating them from below, they can also still be seen several hours after the sun has gone down.
Visit our website for more information on cloud spotting.