In Edvard Munch's famous painting, "The Scream," a figure with an agonized expression holds his face while the sky behind him is composed of colorful, wavy lines. Why is the figure screaming? It turns out, it could be due to those frightening clouds.
Norwegian scientists have theorized that Munch was inspired by a sky filled with mother-of-pearl clouds — also called nacreous clouds — a rare, unforgettable phenomenon.
“Mother-of-pearl clouds appear irregularly in the winter stratosphere at high northern latitudes, about 20-30 km above the surface of the Earth," said the researchers in a presentation made at the European Geosciences Union (EGU) General Assembly.
"The size range of the cloud particles is near that of visible light, which explains their extraordinary beautiful colours. We argue that the Norwegian painter Edvard Munch could well have been terrified when the sky all of a sudden turned 'bloodish red' after sunset, when darkness was expected. Hence, there is a high probability that it was an event of mother-of-pearl clouds which was the background for Munch’s experience in nature, and for his iconic 'Scream'."
Also called polar stratospheric clouds, they only form in high altitudes (about 9-12 miles high) in high humidity with very cold winter air.
"That's when you can get very small ice crystals of about one micrometer," Helene Muri from the University of Oslo told journalists at the conference. "These clouds are very thin and are best seen just before sunrise and after sunset, when the sun is below the horizon. You get these very distinct colourings, from the combination of scattering, diffraction and internal refraction of the sunlight on these tiny ice crystals."
The leading theory for Munch's famous clouds is that the artist was intrigued by colorful sunsets that followed the Krakatoa volcano eruption in 1883, less than a decade before Munch's first version of "The Scream."
There have been notes in Munch's diaries that are said to have referred to the sky and this work:
I was walking along the Road with two Friends – when the Sun set – the Sky suddenly / turned blood red – and I felt as though a wave of Sadness
I paused, / leaned against the Fence tired to Death – above the blue-black Fjord and City the / Clouds hovered like Blood and Flaming tongues
My Friends walked on and I remained behind / shaking with Angst I felt the great endless Scream pass through Nature.
"The Scream" photo: Public domain/Wikipedia