Constable: Nice skies, shame about the rainbows

THE GREAT landscape artist, John Constable had a perfect understanding of clouds and the weather, but cheated with his rainbows, says a leading British meteorologist.

John Thornes has made a 20-year study of the artist's work, and believes Constable is the world's most accurate painter of skies. The artist even discovered and painted the phenomenon known as anti-crepuscular rays, the convergence of the sun's rays on the opposite horizon, a century before scientists recorded it.

He gained his knowledge of the weather as a boy in Suffolk, watching for "messenger" clouds showing the approach of storms that could damage his father's windmill. But the artist who gave us such artistic gems as The Haywain added dramatic effect with rainbows the wrong scientific shape, or which could not exist.

The painter's secrets are revealed in a book by Dr Thornes, former resident weatherman on BBC2's The Travel Show and director of the atmospheric impacts research group at Birmingham University. "Constable's clouds are correct ... but he felt he could use rainbows whenever he wanted," says Dr Thornes. "He sometimes painted a noonday rainbow in a summer scene which is impossible. The sun is too high in the sky at midday between April and September."

One of Constable's classic pieces of artistic licence is in his 1831 work Salisbury Cathedral From The Meadows, now in the National Gallery. The length of shadows in the foreground shows the scene was painted in late afternoon or early evening. This means the rainbow arching over the cathedral tower is too high for that time of day and could be seen only from a different angle.

Dr Thornes has also dated 10 cloud studies painted on Hampstead Heath between 1820 and 1822 by comparing them with contemporary weather records.

He has overturned the accepted theory of why Constable's skies became stormier in later works. Dr Thornes says this was not caused by the death of a friend and the painter's wife, as historians claimed, but was due to Constable's increasing confidence and ability to record accurately what he saw. "No other artist before or since has succeeded in representing our English weather on canvas with such scientific accuracy and a truth to nature," Dr Thornes says.

`John Constable's Skies - a fusion of art and science' by John E. Thornes, published on 30 September by the University of Birmingham Press, pounds 40.

The meteorologist's verdict on The Opening of Waterloo Bridge (1832)

"These are anti-crepuscular rays a century before they were scientifically recorded. Constable used the converging of the sun's rays on the opposite horizon to highlight the bridge built to commemorate the British victory over Napoleon. Even committed experts would see this rare condition only a few times in their lives."

Salisbury Cathedral From The Meadows (1831)

"The painting depicts a thunderstorm over the cathedral. But to get this view of the rainbow, the sun must be directly behind the painter. Foreground shadows show he would need to be in the meadows on the right."

London From Hampstead With A Double Rainbow (1831)

"This documents an even rarer phenomenon known as a rainbow wheel. As in Waterloo Bridge, anti-crepuscular rays highlight St Paul's on the left and form a double rainbow, the colour sequence of the secondary bow on the right correctly reversed. Few people have witnessed simultaneous occurrence of `a wheel with spokes'."