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Since 1951 clouds have remained fairly easy to classify, with about 80 separate classifications officially recognised.

But that could all be set to change next November if one enthusiast can seek official classification of a new cloud type.

Known as Undulatus asperatus, a group are now clamouring for the cloud shape to be included in the International Cloud Atlas.

Scroll down for time-lapse video showing the cloud type 

Ominous: A type of cloud first photographed in Iowa could soon be added to the International Cloud Atlas. Called undulatus asperatus it would be the first new cloud type since 1951. Gavin Pretor-Pinney of the Cloud Appreciation Society is campaigning for the new classification. It is pictured here above Bentley, Suffolk

The campaign is being led by Gavin Pretor-Pinney of the Cloud Appreciation Society (CAS).

For several years he has been leading a charge to name a particular type of cloud undulatus asperatus, but his dream might finally come true next year.

The classification describes a wavy cloud that seems to protrude down from the sky, and is often a sign of a storm being on its way.

The first part, 'undulatus', translates as 'wavy' and is already used to classify certain types of cloud.

Asperatus, meanwhile is the past participle of aspero in Latin - which means 'to roughen'. Thus, the name can be taken to mean 'roughened wave'.

The first images of the cloud formation were taken in Iowa in 2005, before members of the CAS started to find more examples around the world.

Eerie: The conditions in which undulatus asperatus clouds form - namely before or after a storm - is said to be similar to the formation of mammatus clouds. The difference is that high-level winds shape the vapour into waves and swirls in the former (seen here)

BUBBLE WRAP? NO, THIS AMAZING SHAPE IS A 'MAMMATUS' CLOUDS

Pictured here is a mammatus cloud seen in Nebraska earlier this year

The conditions in which undulatus asperatus clouds form - namely before or after a storm - is said to be similar to the formation of mammatus clouds.

The difference is that high-level winds shape the vapour into waves and swirls in the former.

Mammatus clouds look somewhat like bubble wrap. They can involve Hundreds of round 'balls' of cloud hanging in the sky.

They are extremely rare they can usually only be seen when they are low in the sky and lit up by sunlight. While most clouds have flat bottoms, mammatus have round pouches that are caused by sinking air.

This has led to cloud physicists referring to the shape as being caused by negative buoyancy.

The clouds, which often form in turbulent air, can stretch for hundreds of miles and can be a sign of a gathering storm.

For the clouds to form, there must be a sharp change in temperature. 

The name undulatus asperatus (seen here) translates as 'roughened wave' and is said to be a mammatus cloud that has been shaped by wind. A decision will be made on its classification in November 2015.

In a bid to get it formally recognised, the CAS has been gathering many pictures of the formation and helping with academic research. 

Since then the rather complex formation has been spotted in France, Norway, Salcome in Devon, Middlesbrough, Perthshire in Scotland and elsewhere 

And in 2009 Mr Pretor-Pinney first proposed the new classification.

'The formations were more dramatic and exaggerated than usual,' he told the Guardian.

'Undulatus like they were turned up to 11. I began to wonder what would happen if you think there is a case for a new classification.'

Now Mr Pretor-Pinney and the 37,000 or so members of the CAS face an anxious wait to see if their cloud type makes the International Cloud Atlas next November.