Who knows what this symbol means in Apple's own weather forecast?

wind scale

Wind grade and symbol name Wind speed (m) * surface wave height (m) wind.

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.

Weather graphic symbols issued by China Meteorological Bureau.

The cause of wind

The direct cause of the wind is the uneven distribution of air pressure in the horizontal direction. Wind is comprehensively influenced by different factors such as atmospheric circulation, topography and water area, and its manifestations are various, such as monsoon, local sea-land wind, valley wind and foehn wind. Simply put, wind is the directional movement of air molecules.

To understand the causes of wind, we must first understand two key concepts:

Air and air pressure. The components of air include nitrogen molecules (accounting for 78% of the total air volume), oxygen molecules (accounting for about 2 1%), water vapor and other trace components. All air molecules are moving at a very fast speed, colliding with each other and anything on the horizon.

wind energy

The kinetic energy formed by airflow is wind energy. Wind energy is a conversion form of solar energy.

Classification of wind

Wind speed refers to the horizontal distance of air flow per unit time. According to the phenomenon caused by the wind to the ground objects, the wind is divided into 13 grades, which are called wind grades. Record with a number of 0 ~ 12.

wind direction

Wind direction refers to the direction in which the wind blows. For example, the north wind refers to the air flowing from north to south. Wind direction is generally expressed in eight directions. They are: North, Northeast, East, Southeast, South, Southwest, West and Northwest.

reference data

Wind [reference time 2017-12-31]