From a scientific point of view, wind often refers to the horizontal movement component of the air, including direction and magnitude, that is, wind direction and wind speed; but for flight, it also includes the vertical movement component, the so-called vertical or lift airflow. Strong winds can move objects and the direction of objects (mass of matter). The wind is moving very fast.
How is wind formed?
If we give a simple definition to wind, we can say this: the flow of air in the horizontal direction is called wind. Wind is the movement of air from one place to another due to heating or cooling.
We know that the sun shines on different areas of the earth's surface. When the air is illuminated by the sun, the air in some places is hot and the air in other places is cold. Hot air is lighter and easily flies higher, rising above the surrounding cold air; while cold air is heavier and flows toward lighter air, causing the air to flow, thus creating wind.
The formation of wind
The formation of wind is the result of air flow. The main purpose of wind energy utilization is to convert the kinetic energy of atmospheric movement into other forms of energy.
Wind is horizontally moving air. The movement of air is mainly caused by the different intensity of solar radiation received by various latitudes on the earth. In the equatorial and low latitude areas, the sun's altitude angle is large, the sunshine time is long, and the solar radiation intensity is strong. The ground and the atmosphere receive more heat and the temperature is higher. In high latitude areas, the sun's altitude angle is small, the sunshine time is short, and the ground and atmosphere receive The heat is small and the temperature is low. This temperature difference between high latitudes and low latitudes forms a pressure gradient between the north and the south, causing the air to move horizontally. The wind should blow in the direction of the horizontal pressure gradient, that is, the vertical and isobars blow from high pressure to low pressure.
The earth is rotating, and the force that deflects the horizontal movement of the air is called the geostrophic deflection force. This force deflects the airflow in the northern hemisphere to the right and the airflow in the southern hemisphere to the right. Therefore, the movement of the earth's atmosphere is not only affected by the pressure gradient. In addition to force, it is also affected by the direction of the earth's rotation. The real movement of the atmosphere is the result of the combined influence of these two forces.
In fact, surface wind is not only dominated by these two forces, but also is affected to a large extent by the ocean and terrain. Mountain passes and straits can change the direction of airflow movement and increase wind speed. However, friction in hills and mountains reduces wind speed, while isolated mountain peaks increase wind speed due to high altitude. Therefore, the spatiotemporal distribution of wind direction and wind speed is complex.
In the winter, the difference between land and sea affects the movement of air currents. In winter, the continent is colder than the ocean, and the air pressure on the continent is higher than that on the ocean. Winds blow from the continent to the ocean. In summer, by contrast, the continent is hotter than the ocean, and winds blow inland from the ocean. This wind that changes with the seasons is called monsoon. The so-called sea-land breeze is also during the day. The airflow on the continent is heated and expands, rises to high altitudes and flows to the ocean. It cools and sinks over the ocean. The airflow on the near-surface ocean blows toward the continent to compensate for the updraft of the continent. The low-level wind blows from the ocean to the ocean. The continent is called a sea breeze, while at night (winter) the situation is reversed and low-level winds blow from the continent to the ocean and are called land breezes.
In mountainous areas, caused by heat, it blows from valleys to plains or hillsides during the day, and from plains or hillsides at night. The former is called valley wind, and the latter is called mountain wind. This is because the hillside heats up quickly during the day, and the temperature is higher than the air temperature at the same height above the valley. The warm air on the slope flows from the hillside to the top of the valley, and the air in the valley moves up the hillside to replenish the lost air. At this time, it blows from the valley to The wind on the hillside is called valley wind. At night, the hillside is cooled by radiation, and its cooling rate is faster than the air at the same height. The cold air flows down the slope into the valley, which is called mountain wind.
In addition, different underlying surfaces also have an impact on the wind, such as cities, forests, ice and snow-covered areas, etc. have corresponding impacts. Smooth ground or a ground with low friction will increase the wind speed, while rough ground will reduce the wind speed.
Wind level
Zero wind, the smoke goes straight up; Level 1 wind, the smoke is slightly deflected;
Level 2 wind, the leaves are rustling; Level 3 wind, the flag Pianpian;
Level 4 winds cause dust; Level 5 winds cause waves;
Level 6 winds shake big trees; Level 7 winds make traveling difficult;
< p> Level 8 winds, branches are broken; Level 9 winds, chimneys collapse;Level 10 winds, tree roots are uprooted; Level 11, rare land;
Level 12, more Rarely, the wind roars and the waves surge into the sky.