Discovering Clouds
The Greek philosopher Theophrastus (c.372-287 BC) wrote about 'clouds like fleeces of wool'. The French naturalist Jean Lamarck (1744-1829) divided clouds into categories such as 'sweepings', 'bars' and 'flocks'.

A simple and useful cloud classification was devised by the English amateur meteorologist Luke Howard (1772-1864) in 1803.

Why is it Important?
His system is based on descriptions of the general shape, appearance and thickness of clouds, and the heights at which they form. It was similar to the the scientific Linnaeus (1707-1778) devised for plant and animal classification has been adapted to classify clouds in genera and species. He named four main cloud types: cirrus - the Latin for 'hair' for cloud that is wispy and looks like hair; cumulus - the Latin for 'pile' for heaped, lumpy looking clouds; stratus from stratum the Latin word for 'layer' for featureless sheets of cloud; and nimbus - the Latin word for 'cloud' for low, grey rain cloud.

This system became very popular and in 1896 the first International Cloud Atlas was published which is still published today by the WMO. There are now ten main cloud types with a number of sub-categories.