What does a red sky symbolize

The city of Baghdad was called Baldac in the Middle Ages. A gold-interwoven silk fabric was made there, which was given the name canopy. The magnificent sky over a grave, figures of saints, a throne, an altar, a baptismal font, etc. was later made from this material. Canopies are often purple and symbolize the sky. According to mythological beliefs, the sky has the color red, whereby one thinks of the red suns of Egyptian funerary art, the red sun in the Japanese flag and the red painting of vaults in medieval pictures. A canopy can also be a portable protective and honorary roof. In processions, for example, the cross or the monstrance with the holy of holies is carried by the priest under a canopy, with four people carrying it with four poles. The inside of the canopy, the sky, can be red or gold. The canopy is an image of the unity of heaven and earth, a world axis that connects the underworld, earth and heaven. Everything that is under the canopy is inserted into the cosmic and divine order, which means eternity and justice. (based on Hawel Peter: Lexicon of Art & History of Occidental Culture, Munich 2005)