blood rain

The name also given to mud rain, due to the reddish color it usually presents, containing particles of dust of that color, rich in iron oxides. This type of bloody rain is relatively frequent in the countries bordering the Mediterranean, due to the proximity of the Sahara Desert, the main source of that particulate material. In the past, our ancestors came to think that real blood was raining from the sky, which was considered a divine sign foretelling bad omens. In different places around the world, red rains have been documented that do not owe their coloration to desert sand, but to certain microalgae that release a pigment of that color. Their spores are incorporated into the air and travel great distances, in some cases attaining the density necessary to tint that color into the water of raindrops contained in some clouds. This second type of blood rain fits better into the category of rare rains.