Background

Luke Howard has been called "the father of meteorology" for his comprehensive recordings of weather in the London area from 1801 to 1841 and his writings, which transformed the science of meteorology.^[6] Howard had an earlier interest in botany, presenting a paper "Account of a Microscopical Investigation of several Species of Pollen, ..." that was published in the Linnaean Society's Transactions for 1802,^[7] but wrote to Goethe that his passion was for meteorology.^[8]

Howard's On the modification of clouds

In his late twenties, Luke Howard wrote the Essay on the Modification of Clouds, which was published in 1803.^[6] Howard's system was similar to the recently popularized Linnaean classification system developed by taxonomist Carl von Linne.^[9] Howard named the three principal categories of clouds – cumulus, stratus, and cirrus, as well as a series of intermediate and compound modifications, such as cirrostratus and cirrocumulus, in order to accommodate the transitions occurring between the forms. Howard's classification system applied the recently popularized Linnean principles of natural history classification. By applying these principles to phenomena as short-lived as clouds, Howard arrived at an elegant solution to the problem of naming transitional forms in nature.

In his 1803 Essay, Howard included detailed cloud drawings to supplement the written descriptions of his classifications. The drawings of clouds were Howard's own, taken from the rigorous notes and watercolor sketches in Howard's sketchbook. However, the landscapes were done by painter Edward Kennion, as Howard had no formal artistic training. The engravings done by Thomas Milton for the publishing of Howard's essay slightly altered the depictions of the clouds.^[10]

A depiction of a cumulostratus cloud, included in Howard's 'On the modification of clouds'

Howard also emphasized the importance of clouds in meteorology:

"Clouds are subject to certain distinct modifications, produced by the general causes which affect all the variations of the atmosphere; they are commonly as good visible indicators of the operation of these causes, as is the countenance of the state of a person's mind or body."^[11]

Howard strongly believed that "cloud formation and destruction were visible signs of atmospheric processes and were based on the laws of physics."^[9] Howard referred to cloud formation as "nubification", a term that was never popularized. Howard had the same elementary knowledge of cloud physics as many other researchers at the time, including his close friend and chemist John Dalton. Some of this knowledge was generally correct, like Howard and Dalton's belief that clouds were formations of water particles, that the slow speed of the particles' descension was due to air resistance, and that they evaporated right below the cloud base. Howard, however, held some incorrect beliefs about cloud physics. Primarily Howard gave electricity too large a role in the formation of clouds. The knowledge Howard had about cloud physics partially formed his motives for creating a classification system.^[9]

Other cloud classification systems

Howard was not the first to attempt a classification of clouds—biologist Jean-Baptiste Lamarck (1744–1829) proposed a list of descriptive terms in French the same year that Howard presented his essay, containing five terms, four of which overlapped with Howard's system.^[12] The two were not known to have any contact, Lamarck working independently in France, and Howard working independently in England. Despite being presented in the same year, Howard's system gained popularity quickly and became far more widespread than Lamarck's.^[13] Howard's system's success has been said to be due to Howard's use of universal Latin, the Linnaean classification system, and his emphasis on the mutability of clouds. Lamarck's system, however, used French terms and opted for descriptive terms as opposed to a classification system like Linnaeus'. Lamarck's essay proposing his system contained no pictures and was published in an obscure academic journal.^[14] Additionally, Napoleon publicly denounced Lamarck's meteorological work, and Lamarck's system was never well known within his own country.^[15]

Later meteorological work

In addition to his seminal work on clouds, Howard contributed numerous papers on other meteorological topics. He was also a pioneer in urban climate studies, publishing the earliest scientific book on urban climatology, The Climate of London in 1818–20, a 700-page book including continuous daily observations of wind direction, atmospheric pressure, maximum temperature, and rainfall;^[16][17] it also demolished James Hutton's theory of rain, though without suggesting a definitive alternative.^[18] In it, Howard was first to note the urban heat island effect, showing that temperatures in London, compared to those simultaneously measured in the surrounding countryside, were 3.7 °F (2.1 °C) warmer at night, and cooler during the day, and to attribute the concentration of smog (which he called 'city fog') to this phenomenon.^[19] For Rees's Cyclopædia he contributed articles on meteorology, but the titles are not known.

Luke Howard also published the first textbook in meteorology in 1837, Seven Lectures in Meteorology. In the fifth lecture, Howard included the same classification scheme he proposed in 1802, slightly changing his descriptions. Howard notes again the importance of cloud studies for meteorology in the introduction of his work, claiming clouds to be "the subjects of grave theory and practical research...shewn to be governed, in their production, suspension, and destruction, by... fixed Laws."^[17]