The wind blows; there is a strong battle; the wind is rarely blowing at the same speed. The Center for Meteorology and Hydrology reporting on winds often says: wind gusts of grade 5, 6, or 7, also referring to the winds’ nature. Grade 5 and 6 indicate the average wind speed, equivalent to the average wind speed of 8-10 m / s or 10.8¬13.8 m / s; Grade 7 wind is equivalent to the wind speed of 13.9-17.1 m / s. According to China Hydrometeorology Station regulations, the time for observing wind speed is agreed to be the average speed in 2 minutes. Sometimes will have to base on other necessary conditions to calculate the average wind speed in 1 or 10 seconds if the maximum wind velocity is called the gust of wind in a very short period.
Why does the wind blow there is a strong battle, a weak one? We must first talk about the turbulent motion of air currents.
You have seen the smoke in the chimney when escaping all flies upwards, the tiny droplets of water in the mist move-in chaos, the fallen leaves at the corner of the wall will swing in the wind. This proves that the air moves not in a straight line but that the eddy motion does not follow a certain rule. This movement that does not follow a certain rule is the turbulent movement of the air.
When the air currents begin to move, a boundary will first form a boundary in contact with the terrain and terrain on the ground. Due to the rough and uneven Earth surface, the air layer’s movement speed in contact with the Earth’s surface is not only affected by the friction force with the Earth’s surface, causing the movement speed to slow down. But also wrong orbital motion that creates vortexes of air with varying degrees of strength and weakness.
The leaves that fall at the corner of the wall when blown by the wind will swirl around because when the moving air encounters the wall corner’s obstruction. The wind will be pushed into the outside of the corner, but once it passes. The corner of the wall will be swept towards the corner’s back, resulting in circular swirling. Likewise, when the wind encounters tall buildings or mountainous terrain, a vortex of air is formed.
Vortex usually occurs when local convection arises, the ground temperature is uneven, or when two air currents with different velocities or opposite directions will also appear in this phenomenon. All the causes of the air vortex phenomenon are the direction of movement of the air currents that are both straight and circular, in a straight motion. They have diffusion, spreading, or effect use consolidation, morphology, and interference. Meanwhile, the large airflow was still moving in the same direction, but each small airflow was still moving in irregular curves at different speeds. At a certain place, due to the inconsistency of those air currents, the position and direction of the turbulence of the air also frequently change, leading to strong and weak winds.
In places with rough terrain, high friction force, wind speed will be great, wind power will be strong. Therefore, winds in the continent will be stronger than winds in the sea. Winds in the mountains will be stronger than winds in the plains. It is also related to each wind’s speed and severity; the greater the wind speed, the stronger the wind is, the wind speed and average wind speed are also great in a very short time up.