EVEN MORE TO APPRECIATE!:

Last revised in 1987, its new fully-digital edition includes the asperitas after campaigns by citizen scientists. [...]

The World Meteorological Organisation (WMO) publishes the atlas, and also has the final say on the contents, including the addition of "new" clouds and cloud features.

This time around 12 new terms have been added. The best known of these is asperitas, meaning rough-like in Latin, as the clouds can look like the tossing of the waves at sea when viewed from below.

These clouds were first recorded over Iowa in the US in 2006, but soon a torrent of similar images from around the world began to pour in to the Cloud Appreciation Society, a citizen science body.

They began to lobby the WMO for official recognition of the cloud type. But the fact that it has now been officially included came as something of a surprise.

"Back in 2008, I thought the chances of this becoming official were really minimal," said Gavin Pretor-Pinney, president of the society.

"At first the WMO were saying they had no plans to do a new edition, but over time I think they began to realise there is an interest among the public in clouds and there is a need for that interest to be an informed one, there's a need for this authoritative work."

Asperitas becomes the first addition of a new recognisable term since 1953.

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