Xiang Yu Shu (《相雨書》), a book written by Huang Zifa in the Tang Dynasty, collects many experiences and information on weather forecasts before the Tang. [File photo]

Where do you get the latest weather forecasts, from apps on your cell phone, or the Internet?

In ancient China, when people had no satellites, they relied on their direct observation and experiences.

And through years of observation, they accumulated a systematic knowledge of the relations between clouds and weather changes.

In The Book of Songs, the earliest collection of Chinese poems that were created from the Western Zhou Dynasty (c. 11th century-771 BC) to the Spring and Autumn Period (770-476 BC), it is recorded that if it will snow, the clouds in the sky often have the same color and similar thickness.

Thick and dense clouds in summer often herald the coming of heavy rain.

Li Zhao, an officer from the Tang Dynasty (618-907), used "artillery prime mover" to describe the clouds before the storm. He noted this kind of cloud has a flat bottom and a bumped top that looks like many steep hills.

There is also a saying, "when the clouds in the sky bear a shape of a castle, heavy rain will fall on the ground". The castle-shaped cloud also foretells the coming of a storm.

Sunny days can also be predicted from the clouds. Ancient Chinese believed clouds that look like scales indicates a nice day is coming.

Xiang Yu Shu (《相雨書》), a book written by Huang Zifa in the Tang Dynasty, collects many experiences and information on weather forecasts before the Tang. The book points out that if two colors, black and red, both appear in the clouds, it will hail. This description is still used by modern day forecasters.

Without the help of satellites, ancient Chinese also painted many "cloud charts". The earliest cloud pictures Tian Wen Qi Xiang Za Zhan (《天文氣象雜占》) were painted on silk, unearthed from the Mangwangdui Han Tombs. Zhan Yun Qi Shu (《占云氣書》), found in Dunhuang in Gansu province, is a book of cloud pictures finished in the Tang Dynasty.

In Bai Yuan Xian San Guang Tu (《白猿獻(xiàn)三光圖》), completed in the Ming and Qing Dynasty (1368-1911), there are 132 delicate cloud pictures. Each illustration takes the sun, stars, moon, and Milky Way as the background, and adds text explanations alongside the clouds. Most of these pictures follow the basic principles of modern meteorological observation.