Why did some historical rain look red?

In Odd Showers, Gibb gives different explanations for different red-looking falls, rather than one cause for them all^[1].

• Siena, 1860–61: Rain, and some snow, appeared faintly red. Gibb reports an examination that identified organic colouring matter, probably from an algae-like plant; he does not present the precise source as certain^[2].
• Near Aix-la-Chapelle, 1608: A reported “shower of blood” was attributed to red fluid released as chrysalides became butterflies. The stains were reported where butterflies reached, not in the city centre^[3].
• Several red-snow reports: Analyses described fine earthy material containing minerals such as silica, alumina and iron oxide. Gibb suspected volcanic ash in four nineteenth-century cases, rather than establishing that origin as certain^[4].

These are the book’s historical accounts and proposed explanations, not modern confirmation of each event.

Would you also like to know what evidence Gibb gave for the butterfly explanation near Aix-la-Chapelle?DemanderRéponse terminée. Une option de suivi est disponible.