Twelve "new" types of cloud -- including the rare, wave-like asperitas cloud -- have been recognized for the first time by the International Cloud Atlas. From a report: The atlas, which dates back to the 19th Century, is the global reference book for observing and identifying clouds. Last revised in 1987, its new fully-digital edition includes the asperitas after campaigns by citizen scientists. Other new entries include the roll-like volutus, and contrails, clouds formed from the vapour trail of aeroplanes. Since its first publication in 1896, the International Cloud Atlas has become an important reference tool for people working in meteorological services, aviation and shipping. The first edition contained 28 coloured photographs and set out detailed standards for classifying clouds. The last full edition was published in 1975 with a revision in 1987, which quickly became a collector's item. Now, embracing the digital era, the new atlas will initially be available as a web portal, and accessible to the public for the first time.