Anyone interested to-day in weather phenomena is acquainted with the terms used in cloud classification - Cirrus, Cumulus, Stratus, and Nimbus. These have come so far into general use that it is not easy to realize that, until Howard's paper, On the Modification of Clouds, appeared in 1803, no names for classifying clouds were available. Superficially, it may seem that Howard had done nothing more than science has so often done in grouping and classifying and naming the contents of nature. In fact, however, he did something essentially different.
In the introduction to his essay, Howard describes the motives which led him to devote himself to a study of meteorological phenomena:
'It is the frequent observation of the countenance of the sky, and of its connexion with the present and ensuing phenomena, that constitutes the ancient and popular meteorology. The want of this branch of knowledge renders the prediction of the philosopher (who in attending his instruments may be said to examine the pulse of the atmosphere), less generally successful than those of the weather-wise mariners and husbandmen.'
When he thus speaks of studying 'the countenance of the sky', Howard is not using a mere form of speech; he is exactly describing his own procedure, as he shows when he proceeds to justify it as a means to scientific knowledge. The clouds with their ever-moving, ever-changing forms are not, he says, to be regarded as the mere 'sport of the winds', nor is their existence 'the mere result of the condensation of vapour in the masses of the atmosphere which they occupy'. What comes to view in them is identical, in its own realm, with what the changing expression of the human face reveals of 'a person's state of mind or body'. It would hardly be possible to represent oneself more clearly as a genuine reader in the book of nature than by such words. What is it but Ruskin's 'Stand by Form against Force' that Howard is here saying in his own way?
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Before entering into a further description of Howard's system, we must make clear why we disregard the fact that modern meteorology has developed the scale of cloud-formation far beyond Howard, and why we shall keep to his own fourfold scale.
It is characteristic of Goethe that, on becoming acquainted with Howard's work, he at once gave a warning against subdividing his scale without limit. Goethe foresaw that the attempt to insert too many transitory forms between Howard's chief types would result only in obscuring that view of the essentials which Howard's original classification had opened up. Obviously, for a science based on mere onlooking there is no objection to breaking up an established system into ever more subdivisions in order to keep it in line with an increasingly detailed outer observation. This, indeed, modern meteorology has done with Howard's system, with the result that, to-day, the total scale is made up of ten different stages of cloud-formation.
Valuable as this tenfold scale may be for certain practical purposes, it must be ignored by one who realizes that through Howard's fourfold scale nature herself speaks to man's intuitive judgment. Let us, therefore, turn to Howard's discovery, undisturbed by the extension to which modern meteorology has subjected it.
Luke Howard, a chemist by profession, knew well how to value the results of scientific knowledge above traditional folk-knowledge. He saw the superiority of scientifically acquired knowledge in the fact that it was universally communicable, whereas folk-wisdom is bound up with the personality of its bearer, his individual observations and his memory of them. Nevertheless, the increasing mathematizing of science, including his own branch of it, gave him great concern, for he could not regard it as helpful in the true progress of man's understanding of nature. Accordingly, he sought for a method of observation in which the practice of 'the weatherwise mariner and husbandman' could be raised to the level of scientific procedure. To this end he studied the changing phenomena of the sky for many years, until he was able so to read its play of features that it disclosed to him the archetypal forms of cloud-formation underlying all change. To these he gave the now well-known names (in Latin, so that they might be internationally comprehensible):
Cirrus: Parallel, flexuous or divergent fibres extensible in any and all directions.