History of Research on Cloud Types and Naming of Clouds

Abstract. Otto von Guericke was the first who experimentally demonstrated cloud formation by expanding and cooling of compressed air before 1663. Scientists initially grappled with the very question of why clouds float. Early explanations were hindered by limited theoretical understanding, imprecise instruments, and lack of meteorological knowledge.

First attempts for distinguishing various cloud types arose towards the End of the 18^th century. A key turning point came in 1803 when Howard proposed a first systematic scheme using Latin terminology for different cloud types. This effort laid the cornerstone for what would evolve into today's internationally recognized cloud classification system. The way toward an accurate understanding was long and iterative. Early laboratory experiments and rudimentary instruments led to recurring misjudgements that persisted for decades. The advent of manned balloon ascents enabled direct measurements of meteorological parameters in the free atmosphere, though initial findings were compromised by instrumental errors. Over time, as more reliable, bias-free devices became available, scientists could obtain accurate data. New measuring techniques had to be developed for determining cloud altitudes and tracking their motion, thereby enriching the understanding of the atmospheric vertical profiles of temperature and moisture influencing the formation of various cloud types.

Cloud research was further intensified by international cooperation. Beginning in the 1890s, scientists started creating internationally acceptable cloud atlases, despite challenges such as early poor photographs with insufficient contrast. Alternatives, like paintings or cloud watercolours, were even considered to overcome these early hurdles. The intensive observation programs – using daily pilot balloons, kites, and later weather aircraft – allowed researchers to uncover cloud formation processes both in stable and unstable atmospheric conditions. Observations also revealed the discovery of clouds above the tropopause and in the mesosphere. After many national attempts to publish cloud atlases the establishment of the World Meteorological Organization in 1951 paved the way for the modern International Cloud Atlas, published in 1956, which standardized cloud observation practices and naming of cloud types worldwide.