ONE of John Constable's best known paintings, View at Stoke by Nayland, shows a sheet of torrential rain providing the backdrop for a massive rainbow. He has left us a detailed description of its genesis: "The solemn stillness of Nature at a summer's noon attended by thunderclouds is the sentiment attempted in this print. An endeavour was made to give additional interest by the introduction of the phenomena and by some marked circumstances attending them that might occur in such a scene at such a time of day.
But Constable's main phenomenon, alas, is spurious; because of the optical geometry of its genesis, a rainbow at noon in high summer at these latitudes just cannot happen.
This kind of lapse, however, is atypical of Constable, who was born 220 years ago today on June 11th, 1776. In general, he was meticulous on meteorological detail, and his skies in particular were the product of a lifetime's study.
In the summers of 1821 and 1822, for example, he produced a series of detailed oil sketches devoted exclusively to clouds: some 50 of these remain extant, each carefully inscribed on the back with the time of day, the direction of the wind and other memoranda relevant to the weather at the time.
It was a subject on which Constable liked to wax eloquent from time to time. "I have done a good deal of skying," he wrote to a friend in October 1821. "I am determined to conquer all difficulties and that most arduous one among, the rest. The landscape painter who does not make his skies a very material part of his compositions neglects to avail himself of one of his greatest aids.
"The difficulties are very great both as to composition and execution: with all their brilliancy, skies ought not to come forward - indeed they should be hardly thought of any more than extreme distances are - but this does not apply to phenomena or accidental effects of the sky, because they always particularly attract the eye.
It may be that Constable's expertise in this respect owes something to his known familiarity with the work of Luke Howard, a contemporary meteorologist who devised the scientific system of cloud classification still in use today.
In any event, he was one of the earliest painters to recognise the influence of topography on the shapes of clouds and, rainbows apart, his work is invariably accurate in its meteorology.
Because he learned his craft so carefully, and because his skies incorporate always a subtle intimation of continuing change, Constable is an artist much approved of in the weather world.