Release date: 1 May 2018
Clouds are made of tiny water droplets or ice crystals, suspended in the atmosphere. It is commonly observed that dark, threatening clouds can herald a storm, or that fluffy white clouds serenely billow across the sky on a perfect summer’s day. But the science of cloud classification is much more complex than this.
Every cloud belongs to one of the ten main groups, called genera. Most genera are further divided into species and varieties to account for differing characteristics. The basic nomenclature for clouds stems from the Latin term describing their physical form – cumulo (heap-like), strato (layer), cirro (hair-like), alto (high/upper) and nimbo (rain-bearing). Numerous combinations of species and varieties of the genera can be observed, with each telling an important story about the physical processes taking place in the atmosphere.
The Cloudscapes stamp issue depicts types of clouds of their features, using striking photographs taken in Tasmania, South Australia and Queensland.
These striking stamps, designed by Lisa Christensen of Three Branches Design, depict types of cloud or their features.
These dramatic saucer-like clouds, known as lenticularis clouds, are an example of the altocumulus (high and heap-like) genera. They were formed on the crests of atmospheric waves above Lachlan, Tasmania. The stamp photograph is by Rainer Oberle.
These clouds, so named because they resemble udders or mammaries, often occur with cumulonimbus (heap-like and rain bearing). The clouds were photographed near Booborowie, South Australia. The stamp photograph is by Mark Dawson.
These clouds are often associated with unstable weather conditions. Here we see a lightning storm between Auburn and Balaklava, South Australia. The stamp photograph is another by Mark Dawson.
An arcus cloud is a low, horizontal formation appearing as a shelf or roll and usually associated with cumulonimbus clouds. The stamp shows storm clouds with a spectacular arcus feature near Boonah, Queensland. The stamp photograph is by Daniel Lutzke.