A CLOUD formation that is so rare it has not yet been officially classified may have been spotted over the North-East.

What looked like ‘undulatus asperatus’ clouds darkened the skies above Darlington yesterday morning.

The Cloud Appreciation Society first proposed the new classification in 2009. If accepted by the World Meteorological Organisation in Geneva, it would be the first cloud formation added since 1951.

The society came up with the word asperatus from the Latin verb aspero, meaning to make rough, because it was felt the formation looks like the surface of the sea on a choppy day.

Since then the term has been adopted by cloudspotters across the world.