The Beijing Meteorological Observatory issued a blue warning of strong winds. What is the impact of strong winds of magnitude 7?

Level 7 is called gale, which can make trees shake, and it will be difficult to walk in the wind on the road. Huge waves can be set off on the sea, and coastal fishing boats stop in the harbor and go to anchor overseas.

Wind power refers to the strength when the wind blows on an object. According to various phenomena generated when the wind blows on objects on the ground or water, the wind power can be divided into 18 grades, ranging from to 17.

the magnitude of the wind depends on the wind speed, that is, the forward speed of the wind. The greater the air pressure difference between two adjacent places, the faster the air flow, the greater the wind speed and the greater the wind force.

as early as the Tang dynasty, thousands of years ago, the wind power was measured. in addition to recording weather phenomena such as rain and snow, the ancients also measured the wind power.

although no instrument for measuring wind speed was invented in the Tang dynasty, at that time, according to the performance of the wind to objects, the moving speed of the wind was also calculated and the wind level was estimated.

Li Chunfeng's "Phenomenon Play Zhan" records that moving leaves are ten miles, singing songs are hundred miles, shaking branches are two hundred miles, falling leaves are three hundred miles, twigs are four hundred miles, big branches are five hundred miles, stones are thousands of miles, and big roots are three thousand miles. "

This is to estimate the speed of the wind according to the effect of the wind on the trees." Moving leaves for ten miles "means that the leaves are slightly fluttering, and the speed of the wind is ten miles a day;" Singing a hundred miles is the rustling of leaves, and the speed of the wind is a hundred miles a day.

According to the performance of trees,

"First-level moving leaves, second-level singing, third-level shaking branches, fourth-level falling leaves, fifth-level broken twigs, sixth-level broken branches, seventh-level broken trees, flying sand stones, and eighth-level uprooting trees and roots". This can be said to be the earliest wind level in the world.

In meteorology, it can be generally divided into twelve grades according to the magnitude of wind:

Level wind is also called no wind. Smoke goes straight up

1 Soft wind smoke can indicate the wind direction

2 There is a slight noise in the leaves of the breeze

3 The leaves and twigs of the breeze are shaking endlessly

4 The wind, dust and shredded paper are raised, the twigs are shaking

5 The twigs are shaking, there are small waves on the water

6 Strong winds, the branches are shaking, the wires are whirring

7 The whole tree is shaking, and it is difficult to walk against the wind. The headwind resistance is great

9. The gale causes slight building damage

1. Some trees are pulled up by the gale, and the building damage is serious

11. Storms are rare, accompanied by extensive damage

12. Hurricanes are extremely destructive and rare on land.