For artists inspired by what they see in nature, volcanic sunsets are the holy grail of light and color. They transform tranquil sunsets and post-twilight glow into vibrant carnages of spectral radiation. Still, I'm not writing this to put another volcanic-inspired sunset painting on the wall to think about. Instead, I would like to introduce observers to a subtle and little-known daytime phenomenon related to volcanic activity. It may have inspired in part 19th-century Post-Impressionist French artist Georges Seurat (1859-1891) in his attempt to reshape Impressionism and illuminate the world with a new form of art: his own version of optical blending of color, called Pointillism.
The Sky As Art
A number of 19th century artists have recreated volcanic sunsets in their paintings. Most touted are the works of English landscape pioneer William Turner, who spent a year painting the vivid sunsets caused by the 1815 weather-changing eruption of Mount Tambora in Indonesia – the most powerful volcanic event in recorded history.
William Ascroft of Chelsea, London, captured what is arguably the most faithful representation of the sunset sky infused with aerosol from the 1883 Krakatau eruption (aka Krakatoa; also in Indonesia). He made over 500 colored pencil sketches of the changing hues, several of which appear as the frontispiece of the 1888 Royal Society publication, "The Krakatoa Eruption, and Subsequent Phenomena." And in 2004, Don Olson of Texas State University added Norwegian artist Edvard Munch & # 39; s The Scream (1893) to the list of paintings inspired by the sunsets seen in the three years after Krakatau & # 39; s historic blast. .
These performers may not have been alone. In a 2014 paper in the scientific journal Atmospheric Chemistry and Physics, Christos Zerefos of the Academy of Athens in Greece tells how he and his team analyzed red-green proportions in more than 500 paintings by 181 artists, dating between 1500 and 1900. She recognized the effects of volcanic aerosols (namely, a predominance of warm tones) in sunset paintings created within a three-year period following each of the 54 major volcanic events of that period. These include works by Turner, John Singleton Copley, Edgar Degas and Gustav Klimt. The findings are not surprising. But at the top of the list is Seurat.
Georges Seurat painted Bathers in Asnières in 1884 at the age of 24. This gigantic work (118 by 79 inches) depicts a riverside site on the Seine, just 4 miles from the center of Paris. Note how he colored the sky to represent the pollution spewing from the factory chimney in the distance.
(Credit: Wikimedia Commons)
Science on canvas
Born in Paris to a wealthy family, Seurat studied drawing in night school before attending the École des Beaux-Arts in Paris in 1878. During his two-year stay he became disappointed with the academic style of painting – the pedantic use of & # 39; hidden ”brushstrokes and“ slick ”finishes to smooth the surface of a painting. At the same time, he fell in love with the large, distinct brushstrokes in the murals of the French Romantic artist Eugène Delacroix and the radically new styles of the Impressionist painters Claude Monet, Camille Pissarro and others. Their use of visible brushstrokes and experimental application of color, tone and texture worked together to create a vivid visual impression of a fleeting moment in life.
Seurat was more than an artist, he had a great talent for science. He spent hours scouring libraries for books on optics, scientific color theories, and design principles. In particular, he was enthusiastic about the visual effects of complementary colors and the science behind color perception. He probably learned about those topics in Principles of Harmony and Contrast of Colors, and Their Applications to the Arts, a book written in 1835 by the French chemist Michel-Eugène Chevreul.
Seurat left the academy in 1879 to spend a year of military service in Brest, where, according to biographer Daniel Catton Rich, he "opened his eyes to the light effects of sky and calm water." He then returned to Paris, where he began to apply his evolving principles of composition and color.
In his quest for a new approach to painting, Seurat turned to science, including Chevreul's law of simultaneous contrast: how one color can change our perception of another color next to it. Turning away from mixing paint on his palette, he eventually began to apply thousands of tiny dots of pure color in broken strokes – or tiny touches next to each other – directly onto the canvas in a precise way, so that the eye can change the colors instead. mixed. His ever-evolving works reached such an intensity of light that he believed he had discovered the science of painting.
Seurat had not perfected his pointillist technique when he painted his first large-scale composition, Bathers at Asnières. Completed in 1884, it only flirted with its still-evolving pointillist style. Yet one can see in the sky the smoggy effects of air pollution from the industrial chimneys in the distance, a testament to his striving to capture realistic atmospheric optical effects.
A turning point came in the summer of 1884, when Seurat showed the work at the first exhibition of the Group of Independent Artists, of which he was one of the founders. That summer he met the younger Neo-Impressionist artist Paul Signac, who pointed out to Seurat that Bathers lacked the clarity of other Impressionist paintings – the result of his use of muddy earth tones instead of colors of prismatic purity. As Catton Rich notes in his 1958 book Seurat: Paintings and Drawings, Seurat's next monumental work – A Sunday Afternoon on the Island of La Grande Jatte (1884) – “research (s) fully the new laws and principles that he and Signac were developing. "
Seurat preferred his new technique & # 39; color luminism & # 39; (chromoluminarianism), because it not only gives a painting a greater sense of vibrancy, but also a shimmering effect, such as one experiences on a hot summer day while the heat rises from a roadway or sidewalk.
Seurat's use of the technique of chromoluminarianism coincided with the optical effects that followed the August 1883 eruption of Krakatau. skies would have been ignored – especially since the resulting atmospheric optical effects created the most chromatically vivid skies captured in a century. And the vibrancy of light was key to the new artistic movement.
But the Krakatau aerosols also performed light magic in the sky during the day, generating diffuse halos of complementary light that radiated most effectively at noon. Such a sight could have inspired Seurat, especially given that the artist was enthusiastic about the science of diffraction and Rayleigh scattering. It would also be appropriate to suggest that the daytime sky, as painted by the Krakatau eruption, stood as a visual muse to the Neo-Impressionists, inspiring new insights into color and tone that perhaps only science-inspired artists could bring to the fore. can appreciate.
X-rays of Bathers in Asnières reveal that Seurat modified parts of it in the mid-1880s, adding prismatic colors in a pointillist way that create a more vibrant feel. The swimmers weren't quite ready by the time Krakatau erupted in August 1883, and the volcano's accompanying atmospheric effects didn't become vibrant across Europe until November of that year. But the optical effects remained intense at least until 1887, and skywatchers continued to record volcanic atmospheric effects to a lesser extent until the early 20th century. Thus, volcanic skies were present during the short heyday of the French Neo-Impressionist movement, which primarily flourished from 1886 to 1906. To understand how these optically vibrant skies may have influenced Neo-Impressionist thinking, let's fast-forward 100 years to 1982, the year El Chichón broke out in Mexico.
American artist Frederic Edwin Church documented the 1862 eruption of Cotopaxi, about 50 kilometers south of Quito, Ecuador. With a height of 5,000 meters, it is one of the highest volcanoes on Earth.
(Credit: Detroit Institute of the Arts / Wikimedia Commons)
Dappled Hawaiian sky
On March 28, 1982, El Chichón, a dormant volcano in Chiapas, Mexico, awoke from 600 years of dormancy and erupted violently three times a week. One of the most significant volcanic events of the 20th century, the unexpected explosion released 7.5 million tons of sulfur dioxide into the stratosphere, heating it by 7.2 degrees Fahrenheit, and cooling the Northern Hemisphere by 0.72 F. 20 days and changing the Earth's climate years after that.
The stratospheric aerosol cloud initially moved from southern Mexico to Hawaii, where I was living at the time. In a 1983 article by Applied Optics, Kinsell L. Coulson notes that "a significant increase in intensity" occurred during most of the day, creating a "diffuse halo type" over much of the sky. Mauna Loa Observatory lidar measurements over Hawaii in 1982 revealed a six-fold increase in scattering from aerosols and a 25 percent decrease in direct incident radiation.
During my study of the El Chichón-influenced daytime sky, I noticed that it had a "nervous" quality caused by the interplay of tiny flecks of complementary colors. That's why I call it Impressionist Heaven in my Hawaiian diaries. For a casual viewer, the El Chichón aerosols had brushed away the normally crystal blue sky and replaced it with a frost-glass glare of pointillist light – light that was predominantly drenched in blue and orange flecks, with yellow and white flecks, which twinkled with subtle prismatic effects like thrown confetti. This description is reminiscent of a description recorded a month after the Krakatau cramp attack by Captain Parson of the Earnock, who noted that before sunrise the eastern sky was' silver gray, changing to light blue, dotted with numerous small cirrus decorations, pink and pink & # 39; seemed.
Some of the color associated with the aerosol umbrella I saw was linked to the atmospheric phenomenon of the bishop's ring. This huge diffraction corona (created in this case by the scattering effects of volcanic aerosols) covered half of the visible sky and exhibited the color-contrasting halos described by Chevreul, albeit in the opposite order – namely a huge blue orb surrounded by a huge orange halo. The volcanic air seemed to herald the general rule of Neo-Impressionism: "more opposition, more brilliance."
A painting by Seurat moves me because it recalls the spotty complexity of the El Chichón sky: the Eiffel Tower, a montage of predominantly blue, red and yellow color points painted from a vantage point looking southeast across the Seine, where such atmospheric optical effects would be expected.
Seurat unveiled this painting in 1889. He began work on it around February 1887, before completing the painting in his studio, just a few months before the tower's completion in 1889. During this period, the bishop's ring and other aerosol effects were still present. always present in the atmosphere. . Like T.W. Backhouse reports in a March 1889 issue of Nature, "I was informed by Mrs. E. Brown, of Cirencester, that she saw the bishop's ring in full daytime last month, not far from a day at noon."
Adding to the lingering effects of the Krakatau aerosols were aerosols injected into the atmosphere from the 1886 eruption of Mount Tarawera in New Zealand and the 1888 eruption of Mount Bandai in Japan. So it is possible that volcanic aerosols from three different eruptions contributed to the atmospheric effects seen in the Eiffel Tower, whose pointillist style is more brutally captured than in any previous work by Seurat.
The point of the matter?
In the nearly 40 years since the El Chichón eruption, I have rarely witnessed similar large-scale pointillist effects: after the 1991 eruption of Mount Pinatubo in the Philippines, and once in totality at the August 2017 total solar eclipse in Oregon , where the air was affected by rippling waves of smoke from forest fires.
I have observed a similar effect several times on a microscale with a different diffraction phenomenon: the pollen corona (about 3 ° in angular distribution, compared to almost 90 ° in the bishop's ring). In one case, I was able to photograph the pointillist effect in the pollen corona, splintering a blue halo and outer yellow and orange rings into a mixture of juxtaposed prismatic colors, due to scattering effects of the particles in the air.
This pointillist image shows colors of complementary light scattered from pollen grains in a small atmospheric corona. The bright glow is an edging effect of a roof used to block out the sun, around which the colorful corona appeared. (Credit: Stephen James O'Meara)
Isn't it reasonable, then, to at least consider the possibility that the mottled complementary colors in a volcanically drenched daytime sky – which continued in undulations throughout Seurat's brief period as an artist – influenced his pointillist technique?
Unfortunately, we know little about Seurat's methods. He died tragically of an infection in 1891, at the age of 31. The artist left few personal letters and diaries behind; he didn't talk much about his technique either.
However, his interest in color theory is well documented. As Jo Kirby and colleagues explain in an article published in a 2003 National Gallery Technical Bulletin entitled 'Seurat's Painting Practice: Theory, Development and Technology': 'It's important to to realize that nothing in Seurat's art seems to have been disregarded. & # 39;
Stephen James O'Meara is a contributing editor of Astronomy magazine.