The picture here needs little introduction to art aficionados, who will promptly also tell you that it is among the best examples of art about existential angst. But why I have chosen to feature this Munch masterpiece of 1893 would be revealed by the sunset in the background. The reason it is such a bright red is because skies world over were polluted by dust particles thrown out by Krakatoa's explosion ten years earlier. This in turn increased the scattering of light at twilight, leading to these very red sundowns.
The poets, writers, musicians and others of the Romantic era, believed much in the healing, nurturing and nice powers of nature, but sometimes also looked at it 'red in tooth and claw'. Wordsworth (Daffodils), Tennyson (The Brook), Keats and others wrote beautiful things that evoke a gentle rural paradise, somewhat ruined by teaching them in schoolrooms. They sought to create a pastoral Acadia where Man would find escape from his worries.
On the other hand are Hesse (Novembernacht, Steppenwolf), Ibsen (Peer Gynt, A Doll's House and other plays), and Kafka (The Castle), some of the late 19th c. writers whom I have read. They make extensive references to the natural and sometimes even the supernatural exploring the relationship between man as an insecure beast searching for comfort and meaning and an indifferent, even violent nature. The very formless human in the foreground here in the red background is so expressive of what has now come to be known as angst. Who is screaming here - the human or nature? But I must disclaim that these are just my thoughts as a tyro.
I didn't know that the redness drew so much from a real event till I read this Scientific American article. A destructive volcano in Nusantara led to a priceless masterpiece from Scandinavia. To me it tends to illustrates how nature might instruct our affairs much more closely than we think, and not just in a subjective and abstract manner.