Treatise on Armament Technology, Volume 151

On Divination and Measurement

Divination, Section 4

Divination of the Sun, Part 3

The Color of the Sun

When the celestial qiThe term "qi" (氣) here refers to atmospheric energy or vapors. In traditional Chinese science, the interaction between "Tianqi" (heavenly/celestial qi) and "Diqi" (earthly/terrestrial qi) determined weather patterns and the natural order. descends but the terrestrial energy has not yet risen: if these vapors are thick, the sun will appear purple; if they are thin, the sun will appear red. If this occurs at night, the moon will appear white. These are all signs that it is about to rain.

When the celestial energy has not yet descended but the terrestrial energy rises: if the vapors are thick, the sun will appear yellow; if they are thin, the sun will appear white. If this occurs at night, the moon will appear red. This indicates a coming drought as well as wind; it is also the cause of halosoriginal: 暈 (yùn). These are optical phenomena produced by light interacting with ice crystals in the atmosphere, traditionally viewed as significant omens in military divination. appearing around the sun and moon.