Treatise on Armament Technology: Logistics for River Crossings

In no time, if clouds vanish in the southeast during the Mao hour Mao (卯): The period from 5:00 AM to 7:00 AM., rain will fall by the Si hour Si (巳): The period from 9:00 AM to 11:00 AM.. If clouds rise at the Chen hour Chen (辰): The period from 7:00 AM to 9:00 AM. and the southern mountains darken, wind and
rain [will come]. If the sun is seen rising during the Chen hour, or if clouds pass during the Mao hour without rain, the sky will certainly be overcast. Clouds following the wind move swiftly;
wind and rain will cease in an instant original: 霎時; a term used to describe a split second, often used in Buddhist texts to denote the smallest unit of time.. If one encounters clouds moving against the wind, the wind and rain will shift as the hours pass. If black clouds meet the setting
sun, the [severity of] the wind and rain will be beyond words. When clouds spread low across the mountains, rain will fly wildly throughout the night. When clouds rise from the Dragon
Gate Longmen (龍門): Literally "Dragon Gate"; likely a reference to a specific mountain gap or coastal strait that acts as a funnel for weather systems., a typhoon Jufeng (颶風): An ancient term for high-intensity tropical cyclones; the etymological root of the modern word "typhoon." will bring heavy rain. If black clouds arise in the northwest, the thunder and rain will certainly have a crashing roar original: 訇 (hōng); a character representing the sound of a great explosion or the deafening crash of waves.. If the cloud formation
resembles fish scales Yulin yun (魚鱗雲): Known today as Cirrocumulus clouds; a "mackerel sky" often precedes a cold front or a change in weather., the wind tomorrow morning will not be light. If "cloud hooks" Yungou (雲鈎): Hook-shaped cirrus uncinus clouds, which often indicate an approaching warm front and strengthening winds at high altitudes. appear after noon, the wind's behavior will be as fickle as human emotions.
In summer, rain comes from inside the "hook"; in autumn, the wind comes from behind the "hook." One need not worry about morning clouds in the east, but night rain passing to the west is a cause for concern.
When rain squalls come in pairs, a great typhoon will rage across the sky. When ominous clouds are half-open and half-closed, a great typhoon arrives with the wind.
Only then will the wind die down and all become still. When tangled clouds twist at the zenith, wind and rain will come in no small measure. The wind escorts the rain...