https://phys.org/news/2018-07-wavy-clouds-edvard-munch-famous.html

"What's screaming is the sky and the person in the painting is putting his or her hands over their ears so they can't hear the scream," said Alan Robock, study co-author and distinguished professor in the Department of Environmental Sciences at Rutgers-New Brunswick. "If you read what Munch wrote, the sky was screaming blood and fire."

There are four known versions of The Scream: an 1893 tempera on cardboard; an 1893 crayon on cardboard; an 1895 pastel on cardboard that billionaire Leon Black bought for nearly $120 million at auction; and a tempera on hard cardboard thought to have been painted in 1910.