Blood Rain Has Terrified People for Thousands of Years. The Culprit Might Be Growing on Lamp Posts.

4 min readOn an August afternoon in 1841, something ominous fell from the sky near Lebanon, Tennessee. Two enslaved people working in a tobacco field were horrified when they heard a pattering on the leaves around them, followed by what appeared to be blood raining down from the heavens. With that blood came putrid chunks of flesh and fat, turning the field into a scene from the apocalypse.The farm’s owner reported the event to his neighbors, and samples soon made their way to the scientist and collector Gerard Troost. In his report in The American Journal of Science, Troost wrote that “some particles appeared to have been clear blood uncombined with anything else; others, blood united with muscular fiber and fat.” He had no doubt that the substance was animal matter that “belongs to our globe” and hadn’t fallen from the heavens. He believed it could have come only from the shredded carcass of an animal, though he couldn’t tell which kind. When he soaked some of the matter in water, he could make out reddish-brown muscle fibers that he said looked much like dried beef, along with “a distinct smell of animal matter in a state of putrefaction.”Not everyone was satisfied with a scientific answer. As Popular Science recently recounted, one Wisconsin newspaper reported that some Northerners saw the shower as a judgment from heaven against the slavery that still plagued much of the antebellum South. Troost, for his part, hypothesized that a powerful wind had swept up part of a decomposing animal and carried it into an electrically charged storm cloud, where it “was kept in a state of partial fluidity or viscosity.” He also cited earlier unexpected showers of particles that had been mistaken for sulfur. Despite the limits of mid-19th-century science, Troost was partly right. Lebanon’s shower wasn’t the first blood rain, or even the first rain of flesh and blood. The phenomenon goes back thousands of years, and science now offers several plausible explanations for it.Blood showers (with or without flesh) appear in texts as old as The Iliad and the Bible. Some were explained by superstition and folklore, while skeptics looked for a natural cause they couldn’t find. These accounts echo reports of frogs and fish raining from the sky, which once seemed just as inexplicable. Today, meteorologists have a more down-to-earth answer. The 1997 reference work Complete Weather Resource explains that such creatures, and almost anything else once seen as heavenly vengeance, can be caught up in a whirlwind or tornadic waterspout. A waterspout forms when a column of low-pressure air spins violently over a body of water. Powerful updrafts inside its funnel can pull up water, and whatever is in it, then carry it aloft and drop it somewhere else.Lebanon has several lakes nearby today, but they’re 20th-century reservoirs made long after this “blood rain.” In 1841, the closest large body of water was the Cumberland River, several miles to the north, but that distance shouldn’t rule out a waterspout, because these storms can carry what they pick up for miles. Alternatively, if vultures had left a carcass nearby, an ordinary whirlwind could have done the job. Unfortunately, the event happened more than a century before weather satellites could have captured it. No one can say for certain whether a tornado, a tornadic waterspout, or hurricane-force winds (which can also carry some unexpected things) dropped rotting flesh onto the tobacco field. Any strong enough updraft could have been behind it. Wild weather offers a plausible explanation for globs of flesh falling from the sky, but many blood rains have fallen with no flesh at all. That raises a different question: what turns rain red?For much of history, the answer was religious. A decade before the Lebanon shower, in 1831, the enslaved preacher and carpenter Nat Turner had visions he took as signs from God, including “drops of blood on the corn, as though it were dew from heaven.” Later he found hieroglyphic marks written in blood on leaves in the woods. Soon afterward, he led a rebellion in Southampton County, Virginia, in which his followers killed about 55 white people. In the backlash, militias and mobs killed an unknown number of enslaved and free Black people. Was the blood rain in Lebanon another such omen?Modern science suggests a less ominous answer. During the 2001 monsoon season, crimson rain fell on and off across Kerala, India. Physicist Godfrey Louis examined samples under a microscope and found what looked like biological cells. He argued that they were alien microbes released by a comet that broke apart in the atmosphere. However, a government-commissioned investigation found that they were spores of Trentepohlia, a reddish-orange alga that grows abundantly on trees, rocks, and even lamp posts in the region. When researchers grew samples of local lichen in the lab, they produced the same alga found in the rainwater. The spores didn’t come from space or from thousands of miles away. They most likely came from nearby, released in huge numbers and swept into rain clouds by the wind. Other blood rains have been traced to windblown red dust, often from the Sahara, which mixes with raindrops and turns them red.Anyone who wonders whether Peter Gabriel’s 1986 hit “Red Rain” was inspired by such strange weather may be surprised by its actual origin. Gabriel told Mojo that the song began with a recurring dream in which the sea was parted by two walls. Glass-like figures screwed themselves into the walls, filled with blood, and were lowered across the sand to empty on the other side. It turns out that nightmares, like storm clouds, can carry some unexpected things.Elizabeth Rayne is a creature who writes. Her work has appeared in Popular Mechanics, Ars Technica, SYFY WIRE, Space.com, Live Science, Den of Geek, Forbidden Futures and Collective Tales. She lurks right outside New York City with her parrot, Lestat. When not writing, she can be found drawing, playing the piano or shapeshifting.