ONE of the characteristics of the 15th-century Flemish school of painters, compared to artists who had gone before, was the careful way in which they executed skies.
Perhaps the best example of this artistic meteorological Renaissance is The Crucifixion, which hangs in the New York Metropolitan Museum of Art, and, although unsigned, is usually attributed to Jan van Eyck. The painting contains an accurate depiction of virtually every common type of cloud.
Jan van Eyck was born in 1385 at Maeseyck in the Netherlands. He is best known for, the altar piece of The Adoration of the Lamb in Ghent Cathedral, executed jointly with his elder brother, Hubert, and for The Arnolfini Marriage, now in the National Gallery in London. Jan van Eyck died 556 years ago today, on July 10th 1440, in the town of Bruges in what we now call Belgium, and to those weather people who have become familiar with it, The Crucifixion is his masterpiece in meteorology.
The scene is the familiar one, showing a large crowd around the three crosses on Mount Calvary, and the time depicted is the instant when the side of Christ is lanced by the spear of one of the assembled Roman soldiers. The sky, which forms the background of the picture, progresses from a deep blue around the zenith to a milky white as the eye approaches the horizon, a precise portrayal of the range of shading clearly visible in the real in dry conditions.
Also reflecting reality exact the vegetation in the foreground is a greeny-brown, while the distant mountains assume the characteristic azure hue that results from the scattering of the sunlight by the intervening air.
The main cloud type depicted in the work is clearly recognisable as cumulus, showing the characteristic scalloped sides, the rounded tops and a feature often missed: the flat bases, at more or less uniform height, arranged in line. Elsewhere above the landscape, a long stream of cirrus clouds slopes gently downwards from the centre of the sky. Although van Eyck would not have been aware that cirrus consists of trails of falling ice crystals, he has captured their typical appearance to perfection.
Above the cirrus is another patch of cloud that resembles cirrocumulus, while near tile upper left-hand corner altocumulus lenticularis, or mountain-wave cloud, can be clearly seen. The information given by these clouds and three windmills facing the northwest, thereby defining the direction of the wind, allows us to conclude that a cold front had probably crossed the scene an hour or two before and cleared the sky.