《论衡·卷十四·寒温篇》
卦有阴有阳，气有升有降，阳气上升天气就温暖，阴气上升天气就寒冷。
卦有阴阳，气有升降。阳升则温，阴升则寒。
There are yin and yang in hexagrams, and qi rises and falls. When yang qi rises, the weather is warm. When yin qi rises, the weather is cold.