Edgar Degas, J. M. W. Turner and other painters captured centuries of atmospheric records as they illuminated canvases with sunset scenes.
Greek scientists worked with an artist to confirm that the ratio of red to green in sunset paintings, both old and new, increased when particles filled the air, such as after major volcanic eruptions or dust storms. The atmospheric physicists also found a gradual shift in artistic sunset hues over the centuries, possibly due to ever-increasing air pollution during the Industrial Revolution.
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An earlier study, led by atmospheric physicist Christos Zerefos of the Academy of Athens in Greece, discovered that the amount of red relative to green in sunset depictions increased after eruptions, including Tambora, Indonesia in 1815, Coseguina, Nicaragua in 1835 and Krakatau, Indonesia in 1883.
Zerefos' team analyzed 554 paintings created between 1500 and 1900. For up to three years after eruptions, sunsets reddened as sunlight bounced off dust and gas from the volcanoes. The latest study, also by Zerefos, used improved scanning and analysis techniques to confirm the earlier results.
A modern painter, Panayiotis Tetsis, unknowingly repeated the artistic atmospheric observations of classical masters. In the artists' depictions of sunsets over the Greek island of Hydra, the color ratio shifted towards red in paintings done both before (June 19, 2010) and after (June 20, 2010) a dust cloud from the Sahara Desert filtered the sunset's light. Zerefos' team had commissioned the paintings for those dates, but hadn't informed the artist of the impending dust cloud or its potential effect on his craft.
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Zerefos' team correlated the timing of classical paintings' red shift to other records of the atmosphere trapped in ice cores from Greenland, in the recent study published in Atmospheric Chemistry and Physics. The ice cores recorded spikes in sulfur-containing chemicals likely spewed by volcanoes. These spikes corresponded in time to artists' increasingly crimson sunsets.
The comparison of ice and art also revealed a creeping shift in the coloration of the sunset. As the factories of Europe roared into production in the 19th and early 20th century, painting depicted a steady increase in the red to green ratio. The ice cores recorded a steady rise in airborne particles from industrial pollution during the same time.
Photo: Chichester Canal circa 1828 (Joseph Mallord William Turner, Wikimedia Commons)