What is the main impact of the average windy day in China on China?

After winter, it was warm for a while, and the weather finally "recovered". The strongest cold wave in the second half of this year is on the way, and the weather is about to return to what it should be in early winter. The north wind roared and the temperature plummeted.

What is windy weather?

The cold wind is howling in winter and spring. In fact, the wind may be only three or four, which is far from the standard of meteorological gale. In the operational specifications of meteorological observation, the instantaneous wind speed is ≥ 17.2m/s, that is, when the wind reaches level 8 or above, it is generally called gale. Whenever there is a strong wind in a day, it is recorded as a windy day.

In addition to strong convective weather, strong cold air and cyclones (such as typhoons) may also cause strong winds. It should be noted that the following statistics refer to windy days caused by all the above weather systems.

What are the weather systems that produce strong winds?

In China, the strong winds that cause disasters are often caused by the activities of weather systems such as cyclones, cold air, thunderstorms, squall lines and tornadoes.

● Cyclone: Cyclone is a horizontal vortex whose central air pressure is lower than the surrounding air pressure, which is also commonly known as low pressure. In the northern hemisphere, the air in the cyclone area flows counterclockwise, while in the southern hemisphere, it is just the opposite. Because the air pressure in the cyclone center is lower than that in the surrounding area, air flows into the center from all directions, causing strong winds. The continuous convergence of air flow to the center leads to upward movement, and the air flow rises to the upper air and flows out to the surrounding areas, prompting the lower atmosphere to continuously flow in from the surrounding areas to the center. Due to the vertical updraft in the cyclone center, when the cyclone passes through the border, the cloud cover in the central area increases and it is rainy.

China is affected by temperate cyclones all the year round, and typhoons that affect the southeast coast of China in summer and autumn are a special form of intense development of tropical cyclones.

● Cold air: When the cold air moves south, the cold air mass plays a leading role and pushes the warm air mass to move south. The interface between cold air mass and hot air mass is a cold front. A cold front is what people often call a cold air front. Depth Charge, where cold air moves southward, is also the most common weather system affecting China. Due to the large pressure difference between the two sides of the front, it will cause windy weather. When the cold front crosses the border, the air pressure rises sharply, the temperature drops sharply and the wind direction turns clockwise. After the cold front crossed the border, the temperature dropped, the air pressure rose and the weather turned fine.

● Thunderstorm: Thunderstorm is weather accompanied by lightning, showers and strong winds, which is generated in strong cumulonimbus clouds. Thunderstorm gale has obvious diurnal variation and short duration. It usually occurs in the afternoon when the temperature rises the highest, and usually lasts for several minutes to several minutes. The wind area is also small, and the wind direction changes with the movement of the cumulonimbus cloud bottom.

● Squall line: Squall line refers to small and medium-sized strong convective weather with abrupt changes in wind direction and wind speed, which is composed of banded thunderstorms. The width of thunderstorms ranges from less than one kilometer to several kilometers, the widest to dozens of kilometers, the length generally ranges from dozens to hundreds of kilometers, and the maintenance time ranges from several hours to more than ten hours. The squall line appeared unexpectedly. When the squall line crosses the border, the wind direction changes suddenly, the air pressure rises, the temperature drops suddenly, and the wind, rain and hail are mixed, which can cause serious disasters. Before the squall line, the weather was good, mostly southerly, and after the squall line, it turned west or northerly, and the weather deteriorated. The precipitation area is mainly behind the squall line. The wind speed behind the squall line is generally more than ten meters per second, and it can exceed 40 meters per second when it is strong.

● Tornado: Tornado is a sharply rotating funnel-shaped cloud column extending from cumulonimbus clouds. Sometimes it is slightly extended and hidden, and sometimes it hangs in the air or touches the ground. The scale of tornado is very small, and the central air pressure is very low, which leads to a large horizontal pressure gradient and a high wind speed, which is generally estimated to be 50 to150m/s, and the maximum can reach 200m/s. Tornadoes are extremely destructive. Where they pass, they often pull up trees, overturn vehicles, destroy buildings and even take people away.

At high altitude, the windy days are the most.

The number of windy days in China has obvious regional distribution characteristics, while the annual number of windy days in high altitude areas is obviously higher than that in low altitude areas. There are more windy days in the canyon than around.

There are three windy areas in China, namely:

The number of windy days on the Qinghai-Tibet Plateau is more than 75 days a year, with 1/5 days a year, which is the highest in China.