Clouds held a particular fascination for a young Englishman named Luke Howard (1773-1864). His father had sent him to grammar school at Burford, a village to the west of London. But Luke was more interested in the books about nature than in volumes of the Greek and Latin classics.
Before 1800, observers spoke of clouds only as "essences" floating in the sky. Clouds had no names and were not well understood. The nature and behavior of atmospheric gases, such as oxygen and nitrogen, were just being investigated in the laboratories of Great Britain and Europe.
In Luke Howard's school years, high-level dust from volcanic eruptions in Iceland and Japan caused brilliant sunrises and sunsets. To Howard's logical mind, clouds and complicated halos must be the result of cause and effect in the natural order. Luke wanted to know more.
At the age of 20, Howard returned to London to work as a pharmacist. As a hobby, he joined a group of scientists, known then as "natural philosophers," who called themselves the Askesians (searchers after knowledge). Each member, in turn, read a scientific paper to the others. Luke Howards turn came one night during the winter of 1802-03. His paper was titled, "On the modification of clouds." In our current language, modification means classification. This paper was so well received that it was published and it has become a classic in the history of science. Today we still use the basic scheme that Howard presented that night and the Latin names he assigned to the clouds.
Classifications of Clouds
Howard noted that there are three basic shapes to clouds:
- heaps of separated cloud masses with flat bottoms and cauliflower tops, which he named cumulus (Latin for heap);
- layers of cloud much wider than they are thick, like a blanket or a mattress, which he named stratus (Latin for layer);
- wispy curls, like a childs hair, which he called cirrus (Latin for curl).
To clouds generating precipitation, he gave the name nimbus (Latin for rain).
Clouds are found in three layers in the lower atmosphere. Thus, with four types of clouds and three layers, we come up with 12 major cloud types that have evolved from Howard's pioneering work.
- Heaps:Cumulus family
- Fair weather cumulus
- Swelling cumulus
- Cumulus congestus
- Layers: Stratus family
- Stratus
- altostratus
- cirrostratus
- Layered Heaps
- stratocumulus
- altocumulus
- cirrocumulus
- Precipitating clouds
- cumulonimbus
- cirrus
- nimbostratus
|