The cause of strong wind

Strong winds on the ground occur under certain circulation and weather conditions. According to the causes of gale formation, the surface gale in China can be roughly divided into the following types: northerly wind after cold front, southerly wind after high pressure, gale during the development of temperate low pressure, typhoon gale, tornado and thunderstorm. Different regions and seasons are affected by strong winds. In winter and spring, with the outbreak of cold air, large-scale windy areas often appear in northern provinces, mainly northerly winds. Large-scale winds in summer are mainly caused by typhoons. Strong winds with wind speed exceeding 17m/s are mainly caused by cold waves, thunderstorms, typhoons and tornadoes. Cold waves and strong winds are almost all over the country, and typhoons and strong winds mainly affect China's coastal areas. Thunderstorms and tornadoes have certain regional characteristics, so the distribution law of annual average gale days has obvious regional changes. In China, the average number of windy days in most areas is 5? 50 days, including North China, Northeast China, Northwest China and Qinghai-Tibet Plateau 10? 75 days, southwest, south China and the Yangtze River basin is 3? 25d. There are four areas with more days in China, namely Qinghai-Tibet Plateau, China-Mongolia border area, northwest Xinjiang, southeast coast and islands, and northeast Songliao Plain. In addition, some passes located in high mountains, river valleys and mountainous areas are also windy areas, such as Alashan Pass in northern Xinjiang, where the number of windy days reaches 163d. In most parts of China, the number of windy days is the most in spring, followed by winter and the least in summer. Strong winds or strong winds may cause damage to tourist facilities, tourist buildings, tourist landscapes, communication lines and vehicles. The degree of disaster caused by windy days is mainly related to the magnitude and duration of wind power. Gale For shipping, the strong crosswind perpendicular to the runway will cause the danger that the aircraft will slip off the runway or tilt when taking off and landing; In highway transportation, strong winds carry a lot of snow or sand, which affects the sight and speed of cars, leading to an increase in traffic accidents, vehicle delays and even traffic interruptions, especially in the tuyere area, where strong winds may even overturn vehicles and cause traffic accidents; On the railway, strong wind may cause damage to railway bridges, vehicles, telecommunications equipment and lines. Strong winds may cause trains to be delayed or even overturned. In the tuyere area of Lanzhou-Xinjiang railway in China, there have been many incidents in which trains were overturned by strong winds. For ships sailing in the ocean and inland rivers, strong winds will cause the ship to capsize, and in complex waterways, strong winds will make the ship yaw and hit rocks.