Is the "North Wind Level 4" strong? How old, 100 points reward.

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 typhoon 32.7- destructive waves +04.0

Note: The wind speed listed in this table refers to the wind speed value at10m above the flat ground.