How to determine the level of wind?

Level 0, no wind, still smoke rising straight up.

Level 1, soft wind, leaves moving slightly, smoke can indicate direction.

Level 2, light wind, leaves rustling slightly, and people feel windy on their faces.

Level 3: Breeze, leaves and twigs swaying, and flags can be unfurled.

Level 4, gentle wind, can blow dust, pieces of paper, and sway small branches.

Level 5, light wind, sometimes small trees swaying, and small waves on the inland water surface.

Level 6, strong wind, big branches shaking, power lines whirring, making it difficult to lift an umbrella.

Level 7, strong wind, the whole tree shakes, big branches bend down, making it difficult to walk in the wind.

Level 8, strong wind, broken branches, great resistance to walking in the wind.

Level 9, strong wind, the roof of the bungalow was damaged and the hut was damaged.

Level 10, strong wind, can uproot trees and blow down buildings.

Level 11, storm, rarely seen on land, very destructive, causing heavy losses.

Category 12 hurricanes are rare on land and are extremely destructive.