Oh great, it’s raining blood again! I hope it’s just rain dust from the desert and not intercontinental cloud algae.
Blood rain has been an ill omen (or is it a portent?) for thousands of years: Homer wrote about it in the Illiad, as did Plutarch, Livy, Pliny the Elder (that guy again?), Geoffrey of Monmouth, William of Newburgh… Funnily enough, I don’t think there’s a biblical reference to blood rain, just to rivers and oceans turning to blood. Nevertheless, it’s firmly entrenched in the ledgers of supernatural events.
Blood rain has also happened in modern times: Provence, France in 1608; Apulia, Italy in 1803; Kerala, India, in 2001. Fortunately, scientists are on the job and here to work out just what’s going on.
In the Italian example, Giuseppe Maria Giovene had the best theory. He was a scientist, but also an ichthyologist, meteorologist, entomologist, and archpriest! So he was a qualified generalist. His theory: sand from the Sahara blowing up the Mediterranean and into the Italian blood rain. Boring but probably true: we now know that rain dust is the cause of most blood rain.
Not all blood rain, though. The Kerala outburst was traced back to tiny algae, the same that are present in lichen, and (this is really neat) the algae came from Austria. 7000km away.
Certain species can propagate across continents inside clouds: algae, bacteria, and fungi. Intercontinental cloud algae! I did not know this, and now I’m looking suspiciously at every cloud that passes by. Although given that my home is going through a pretty severe drought at the moment I don’t have to do that too often.