The small trees swayed eastward because of the west wind.
Explanation of wind direction:
1. Wind direction refers to the direction in which the wind blows, and the direction in which objects move under the influence of the wind is the direction in which the wind goes. For example, the wind blowing from the south is called south wind, the wind blowing from the east is called east wind, etc. Wind is the external manifestation of atmospheric flow and is applicable to the principles of fluid mechanics.
2. The direction in which the wind blows. It is usually understood through the basic direction or bearing. There are various instruments used to measure wind direction, such as windsocks and wind vanes. A weather vane points in the same direction as the wind, while a windsock points in the opposite direction.
3. Modern instruments include electronic wind speed, which can also measure wind speed and direction. Meteorological stations forecast wind times. When the wind direction swings left and right in a certain direction and it is uncertain, the word "bias" is added, such as northerly wind. When the wind force is very low, the explanation is "the wind direction is uncertain".
How the wind was measured in ancient times: The ancients invented a wind measuring tool called "綄" or "俔".綄[huán], the Chu people called it "five liang". Liu An of the Western Han Dynasty recorded in "Huainanzi": "If the 綄 (俔) is waiting for the wind, it does not need to be settled in a moment." Gao You, a scholar of the Eastern Han Dynasty, noted: " Hao is also a person who waits for the wind.
It is made of chicken feathers weighing five taels (or eight taels) and hung on the flag. Even if there is a little wind, the 焄 will be blown away. Move. The 綄 is still a must-have for ancient combat troops. The "Book of War" says: "Whenever the wind is used, eight taels of chicken feathers are used to build a five-foot-long flag, and the feathers are tied to the top and set up in the military camp. "
The Houfeng Flag was called "Xiangfeng Flag" by people in the Tang Dynasty, and "Zhanfeng Flag" by people in the Song Dynasty. Although the names were different, the functions were the same. In the Song Dynasty, there was a Suzhou native named Jiang Yingshu. He was very good at using the Zhanfeng Flag. Li Lao of the Song Dynasty recorded in the book "Talks between Teachers and Friends" that Uncle Jiang Ying "was well versed in Feng Shui and tried to set up a flag in front of the office where he lived, called Zhanfeng Flag, so that people could wait for it. Set up a residence. ”
In addition to the Houfeng flag, the most widely used wind measuring instrument by the ancients was the "Xiangfengwu". It is said that it was invented in the era of Shun and Yu. The Jianzhang Palace built in the first year of Emperor Wu of the Han Dynasty (104 BC) had a "Phoenix Tower" on it. The wind measuring instrument is known as "Bronze Phoenix" and commonly known as "Bronze Bird".
The Bronze Phoenix was improved in the Eastern Han Dynasty and was called "Xianfeng Tongwu". It was found in the Eastern Han Dynasty Tomb in Lujiazhuang, Anping County, Hebei Province. A large architectural mural was unearthed, in which there is a Xiangfengwu and a wind measuring flag on the bell tower. This is the earliest wind measuring device "Xianfengwu" pattern discovered so far. The Xiangfengwu was used until the Qing Dynasty. /p>