At present, wind power in China is classified as 18. However, at the beginning of19th century, Francis beaufort, a British scholar and admiral, drafted a wind assessment report. In 1805, he divided the wind into 13 grades by observing different objects and using different winds. At present, the wind assessment method used internationally is called Beaufort scale. At first, it was only used as a reference index for navigation and naval operations, and later it was improved and applied to land.

Level 0 wind: no wind, with a wind speed of 0.0-0.2m/s (

1 wind: it is a light wind, with a wind speed of 0.3-1.6m/s (1-5km/h). Ground smoke indicates the wind direction, and there is no water drop at the microwave peak of waves.

Level 2 wind: small wind, wind speed1.6-3.4m/s (6-11km/h), the ground objects feel windy, and the small wave crest is not broken.

Level 3 wind: light wind, with the wind speed of 3.4-5.5m/s (12-19 km/h), the ground image standard flutters in the wind, and the small wave crest is broken.

Level 4 wind: light wind, the wind speed is 5.5-8.0m/s(20-28km/h), and dust is blown by objects on the ground, with small waves and much foam.

Level 5 wind: Breeze, with a wind speed of 8.0-10.8m/s (29-38km/h), with small trees swaying on the ground, broken waves and foam peaks.

Level 6 wind: strong wind, wind speed 10.8- 13.9 m/s (38-49 km/h), noisy ground features and soaring waves.

Level 7 wind: strong wind (high wind), wind speed 13.9- 17.2 m/s (50-6 1 km/h), ground objects are difficult to walk, and waves break the peak and spit into strips.

Level 8 wind: strong wind, wind speed 17.2-20.8m/s(62-74km/h), ground objects break branches, and waves are high.

Grade 9 wind: strong wind, the wind speed is 20.8-24.5m/s(75-88km/h), the ground objects slightly damage the house, and the wave peaks roll.

10 wind: strong wind, with the wind speed of 24.5-28.5m/s(89- 102km/h), trees are pulled up by ground objects, and the waves roll and roar.

1 1 wind: storm, the wind speed is 28.5-32.6m/s (103-117km/h), the ground objects are seriously damaged, and the peaks are all water drops.

12 wind: typhoon (first-class hurricane), with a wind speed of 32.6-37m/s (117-134km/h), with great damage to ground objects and extremely high waves.

13: typhoon (first-class hurricane) with wind speed of 37.0-41.4 (134-149).

14: Strong typhoon (category II hurricane) with wind speed of 41.5-46.1(150-166).

15: strong typhoon (category 3 hurricane) with wind speed of 46.2-50.9 (167-183).

16: super typhoon (category 3 hurricane) with wind speed of 51.0-56.0 (184-201).

17: super typhoon (category 4 hurricane) with wind speed of 56.1-61.2 (202-220).

17 and above: super typhoon (category 5 hurricane) with wind speed >; 6 1.3(& gt； 250)