The distance that the wind moves in unit time is called wind speed, and the unit is meter/second or kilometer/hour; The direction of movement is called the wind direction.
1805, Frincis Beanfort, an Englishman, classified the wind power into 13 according to Yi Sizhan written by Li, an astronomer in the Tang Dynasty, with the lowest being 0 and the highest being 12. The wind speed of class 0 wind is 0.0 ~ 0.2 m/s, which is called no wind. The poem "Lonely Smoke in the Desert, Long River Falling in the Yen" by the poet Wang Wei in the Tang Dynasty describes a 0-level landscape. 1 the wind speed is 0.3 ~ 1.5 m/s, which is called soft wind. The numerical range of wind speed at each level gradually increases from bottom to top. If the third-class wind speed is 3.4 ~ 5.4 m/s, it is called breeze, with a difference of 2.0 m/s from top to bottom; The wind speed of Grade 4 wind is 5.5 ~ 7.9 m/s, which is called breeze, with a difference of 2.4 m/s from top to bottom. The wind scale created by Beaufort is scientific, accurate, universal and applicable, and has been recognized and adopted by meteorological circles and the whole scientific community in various countries.
After Beaufort scale, "Beaufort scale" has been revised and supplemented many times, and now it has been extended to 18. For example, the wind of 1 1, that is, the wind that meets the standard of typhoon now, has a wind speed of 32.7 ~ 36.9 m/s, and the wave height on the sea surface is generally 14.0 m, which is marked as "great waves" and "very few on land and extremely destructive". Wind, wave height and land and sea signs above 13 are difficult to express; For example, the wind of 1 1, that is, the wind that meets the typhoon standard now, has a wind speed of 32.7 ~ 36.9 m/s, which is also called a hurricane. The wave height on the sea surface is generally 14.0 m, marked as "great waves" and "few on land, which is extremely destructive". Wind, wave height and land and sea signs above 13 are difficult to express; The highest level-17 wind speed is 56. 1 ~ 6 1.2m/s, and the wind speed above 17 is extremely rare, but it is by no means unheard of, but the standard for measuring its level has not yet been formulated.
Wind speed, direction and wind power
Wind is represented by wind vector and consists of wind stems and wind feathers. Wind handle: indicates the direction of the wind, with 8 directions.
Wind feather: 3 or 4 short strokes and triangles indicate strong wind, perpendicular to the right side of the wind pole (northern hemisphere).
wind scale
* Note: The wind speed listed in this table refers to the wind speed value at10m above the flat ground.
Wind grade and symbol name Wind speed (m) * Sea surface wave height of land image (m)
0 No wind, 0.0-0.2 smoke, straight up, calm, 0.0
1 soft wind 0.3- 1.5 smoke indicates that the wind direction is at the peak of microwave 0. 1 and there is no water drop.
2 breeze 1.6-3.3 Feel the wind, and the small wave crest will not be broken by 0.2.
3 breeze 3.4-5.4 standard propagation wavelet peak rupture 0.6
4 breeze 5.5-7.9 blows dust, small waves, foam peak 1.0.
5 Strong breeze 8.0- 10.7 Waves and foam peaks in swaying young trees 2.0
6 strong wind 10.8- 13.8 wire sound waves to water droplets 3.0
7 gale 13.9- 17. 1 difficulty in walking, peak breaking, foam strips 4.0
8 strong wind 17.2-20.7 damaged branches, wave 5.5.
9-level gale 20.8-24.4 Small damaged houses wave crest rollback 7.0
10 gale 24.5-28.4 uprooting trees, waves rolling and roaring 9.0
1 1 Storm 28.5-32.6 was generally damaged, and the peaks were all in water droplets 1 1.5.
12 hurricane 32.7- devastating waves.