On a cold winter evening in 1802, the 40 or so members of an amateur science club made their way down a steep flight of stairs into a cavernous laboratory in London, where a nervous young man was preparing himself to deliver that evening's lecture.
The usual discomforts of public speaking would have been worse for a Quaker, and worse still for one as self-doubting and preoccupied as the 30-year-old chemist Luke Howard. Even the title of his lecture, "On the Modification of Clouds", seemed modest and understated compared with the titles of some of the other talks that had been delivered to the science club over the course of that winter: "On the Explosivity of Gunpowder", for example, or "On the Surprising Powers of the Divining Rod".
But anyone who doubted the potential significance of Howard's lecture on that particular winter night would have been in for a surprise. What the audience was about to hear remains one of the most extraordinary episodes in the history of British science: the naming of clouds by an unknown young amateur meteorologist who, by the end of the evening, was being heartily congratulated by the members of his audience and whose fame, by the end of the following year, had spread throughout the scientific world.
Howard was not the first to have attempted to understand clouds. Since antiquity, they have offered a challenge to observers to provide a satisfactory account of their cause and behaviour, while their fleetingness has also supplied a powerful image of the changeability and transience of life. "The patron goddesses of idle men", as the Athenian playwright Aristophanes described them, clouds have long been a subject close to the hearts of scientists and daydreamers alike.
Many Greek and Roman scientific thinkers, such as Aristotle, Seneca and Lucretius, offered hopeful and often ingenious explanations of cloud formation and structure, but none of them ever hazarded a taxonomy or a systematic method of classification. The compilers of the Norse myths, however, came close to a kind of mythical taxonomy, devising a sequence of cloud types that took their definition from the altitude at which they were found: the high wispy clouds which we now call cirrus, for example, were spun by Frigg, the wife of Odin, on her wheel and distaff in her celestial home in the Hall of Mists of the Sea. The lower cumulus clouds were flung upwards during the summer months by the dying frost giant Ymir. And the ghastly citadel of Hel was shrouded in a permanent brooding sheet of the low-lying cloud that we now call stratocumulus.
Myths aside, it wasn't until the 17th century and the coming of the scientific revolution that natural philosophers (as scientists then called themselves) began to emphasise the importance of classifying natural objects into groups and categories in order to establish the connections and the differences between them.
In the early 18th century the Swedish botanist Carl von Linne (known to the Latinising world as Linnaeus) introduced the system of binomial nomenclature to natural history, in which every identifiable kind of organism could be designated by a pair of Latin names. The first denoted the genus to which the organism belonged, while the second denoted its species. Acer japonicum, for example, referred to the Japanese maple, while Canis familiaris referred to the domestic dog. The Linnean system of naming allowed connections and differences to be recorded across a wide spectrum of natural history and it proved hugely influential, inaugurating the great age of scientific naming and fixing, during which everything, from the greatest of the mammals to the smallest of the microbes, was classified for study or stuffing.
Howard, like most scientifically minded men and women of the age, was familiar with the Linnean system, as well as with Latin in general. He had been sent to a Quaker boarding school in Oxfordshire where Latin formed the heart of the curriculum. It was there, according to Howard, that he began noticing the shapes of the clouds, as he stared out the schoolroom windows.
"I settled in my mind one remarkable configuration of the clouds in a full sky." he recalled later, "because it was of rare occurrence." He kept notebooks of his observations of the skies. It was this early combination of schoolroom Latin with an innate curiosity for natural forms that would lead on to his achievement in 1802, when he gave the clouds the names by which they are still known today.
But while Howard's audience at the science club lecture would have been familiar with the Linnean system, they would have known very little about clouds. Meteorology was one of the sciences' slower developers and even by the early 19th century it had advanced little beyond the wisdom of ancient proverbs such as "red sky at night: shepherd's delight; red sky at morning: shepherds take warning".
Part of the problem with meteorology, of course, was the intangibility of many of the phenomena which it studied. Unlike its neighbouring disciplines such as botany or geology, it was difficult to do the kind of fieldwork that would build up a collection of samples that could be studied at leisure, then named and arranged into a revealing system.
The language of classification was the backbone of scientific study in Howard's time - much more so than it is today - with the cabinet of samples acting as its primary tool. Meteorologists, therefore, suffered the distinct disadvantage of being unable to collect study samples of winds, clouds or rainbows. All they could collect were statistics of rainfall, wind-speed, temperature and pressure.
And, as Howard pointed out at the beginning of his lecture, "the philosopher who attends only to his instruments may be said only to examine the pulse of the atmosphere." What was needed, in his view, was a foundation of classification on which meteorology could be built into a recognisable modern science. And clouds, he felt sure, were the key to the problem.
Clouds, according to Howard, are the visible signs of the otherwise invisible processes of the atmosphere. They write a kind of journal on the sky which, were we to take the trouble to learn to read it, would allow us to understand the patterns of weather and climate much better than before.
Howard had devoted much of his time to learning to read this language of the sky and the result of his labours were presented in his brilliant lecture of December 1802.
What led to the success of Howard's classification was his simple but penetrating insight that clouds have many individual shapes but few basic forms. All clouds belong to one of only three main families, he claimed, to which he gave the names cirrus, cumulus and stratus. Every kind of cloud is either a modification of, or a transition between, these three.
Following the Linnean example, Howard took his names from Latin: cirrus (fibre or hair); cumulus (heap or pile); and stratus (layer or sheet). He then named other, intermediate cloud forms according to their relation to these principal types. So a high, wispy cirrus cloud that descended and spread into a sheet was named as cirrostratus, while groups of fluffy cumulus clouds that joined up and spread were named as stratocumulus. Howard identified seven cloud types in his original lecture, and these have since been expanded to 10: cirrus, cirrocumulus, cirrostratus, altocumulus, altostratus, nimbostratus, stratocumulus, stratus, cumulus and cumulonimbus.
What was so ingenious about this apparently simple system was that it allowed for the changeability of clouds. Howard recognised that clouds continually merge, rise, fall and spread throughout the atmosphere and across the sky, rarely maintaining the same shape for more than a few minutes. His classification allowed for all this restless movement and change; it allowed the clouds to move and modify, and exercise their elemental freedom. This was something new in science, as many of Howard's contemporaries realised, and when it was published in 1803 his classification was to have a widespread impact, not just on the development of atmospheric science, but on early 19th-century European culture as a whole.
Johann Wolfgang von Goethe, the greatest intellectual icon of his age, wrote a series of poems in praise of Howard's clouds, in which he eulogised the scientist for his "clearer mind", and which ended with the lines: As clouds ascend, are folded, scatter, fall, Let the world think of thee who taught it all.
Percy Bysshe Shelley also wrote a poem, "The Cloud", in which each of Howard's cloud types was characterised in turn. But perhaps the most impressive response to Howard's naming of clouds was in the work of the artist John Constable, who spent two entire summers on Hampstead Heath painting clouds in an effort to understand them meteorologically as well as visually. He owned a copy of Howard's published lecture, which he annotated carefully, and he also wrote weather notes on the back of each of his sketches. There are more than 100 of these oil sketches still in existence and they are now among the most revered of all Constable's works.
Howard himself, however, did not enjoy the scientific celebrity that his classification brought him. As a Quaker, he viewed worldly acclaim with something approaching trepidation and although he continued to pursue his meteorological interests, publishing a number of books on the subject, he kept himself at a distance from public science. "I am a man of domestic habits", he wrote in a memoir, "and very happy in my family and a few friends, whose company I quit with reluctance to join other circles."
So Howard's names have continued to be used all over the world, but his own name has largely been forgotten, which is what he would have wanted. He died in 1864, aged 91, and was buried in an unmarked grave.
However, on a cold April morning in 2002, 40 or so members of an invited audience gathered on a London pavement to witness the unveiling of an English Heritage blue plaque in honour of the memory of Howard. Michael Fish, the BBC weather forecaster, presided over the event, which was organised and hosted by the Met Office. The wording of the plaque on the wall of 7 Bruce Grove, Tottenham, where Howard spent the last 12 years of his life, is beautifully succinct:
Lived and Died Here".
* Richard Hamblyn is the author of The Invention of Clouds: How an Amateur Meteorologist Forged the Language of the Skies (Picador, pound;7.99), which tells the story of Luke Howard and the naming of clouds. He is currently completing a book about natural disasters in history, as well as editing Daniel Defoe's The Storm for Penguin Classics