“The team at the National Observatory of Athens held a survey in 2007, in which they used 554 paintings by 181 painters, dated between 1500 and 1900, representing sun- sets and studied the coloration of the depicted atmosphere, with the aim of providing a new look at the reconstruction of the aerosol optical depth (AOD) before, during and after major volcanic eruptions, during a time when atmospheric observations were largely nonexistent. Considering the fact that sunlight scattered by airborne particles appears more red than green, the researchers found that most pictures with the highest red/green ratios were painted in the 3 years following a documented volcanic eruption.

“The 554 paintings were divided into two groups, “volcanic sunset paintings” and “non-volcanic sunset paintings.” The first group was the main focus of interest of the team; it consisted of 54 artworks by 19 artists, created within a period of 3 years following a major volcanic eruption. As the researchers wanted to detect atmospherical abnormalities in works painted by one artist before, during and after an eruption, they narrowed the number of artworks under consideration even further. They could find only five artists who had painted sunsets represent- ing all three scenarios: John Singleton Copley (1738–1815), Joseph Mallord Turner (1775–1851), Caspar David Friedrich (1774–1840), William Ascroft (1832–1914) and Edgar Degas (1834–1917). In the periods during which these five artists were active, the following volcanic eruptions occurred: Laki (Iceland, 1783), Tambora (Indonesia, 1815), Babuyan (Philippines, 1831), Coseguina (Nica- ragua, 1835) and Krakatau (Indonesia, 1883), respectively.

“In order to measure the amount of redness in the light depicted in these works, the researchers calculated their red/green (R/G) ratios, based on a classic study by Jameson and Hurvich in which it is maintained that the amount of redness in monochromatic light can be measured by combining it with a second light that appears green when viewed alone. They used the UVspec model in order to simulate and calibrate the R/G ratios. Abnormalities seen in time series of R/G values for the work of each artist were accepted as natural ones and have not been attributed to the individ- ual painter’s aging, as color perception stays the same over the years.

“The measurements of the R/G ratios for the paintings created during or over the 3 years following a volcanic eruption were 1.3–1.4 times greater than those be- fore and immediately after the event. In the Zerefos report, these color abnormal- ities are explained as due to the volcanic eruptions and as being very close to esti- mates from historical observations, early measurements and material found in ice cores. The conviction of the research team was that artists “have simulated the colours of nature with a remarkable pre- cise coloration” , as is proved by the high correlation coefficient of 0.83 be- tween the index of volcanic activity (DVI) and the R/G values of the paintings: It was calculated through 88 pairs, which is—according to the team—of high sta- tistical significance.

“At the end of their paper the researchers mention the famous work by Edvard Munch, The Scream, which they did not include in their survey because they could not find a certain date for it in the literature: Robock dates it to 1892 [10], while Olson puts its creation in the win- ter of 1883–1884. If the first dating is valid, its high R/G value, over 2.10, can only be explained—the researchers say— as reflecting Munch’s memory of the red atmosphere that followed the eruption of Krakatau in 1883. The article closes with the researchers’ wish: “Through the eyes of painters and other artists it is ex- pected to get information on past natural phenomena that have escaped attention of scholars until now,” and with the cita- tion of J.M.W. Turner’s words: “I did not paint it to be understood, but I wished to show what such a scene was like”.

Text: Eleni Gemtou, Depictions of Sunsets as Information Sources, LEONARDO, Vol. 44, No. 1, pp. 49–53, 2011.

Image: Joseph Wright of Derby, Vesuvius in Eruption, with a View over the Islands in the Bay of Naples, circa 1776. Oil on canvas, 122cmx1764cm.