What is the scope of the typhoon?
The influence range of typhoon is usually based on the nearly circular isobar in the outermost circle of the system, with a diameter of 600 to 1000 km, the largest of which can reach 2000 km, and the smallest is only about1000 km. Typhoons mainly affect the southeast coastal areas of China.
Typhoon is a kind of tropical cyclone. Tropical cyclone is a low-pressure vortex that occurs on the surface of tropical or subtropical oceans, and it is a powerful and profound "tropical weather system". In China, tropical cyclones in the northwest Pacific are classified into six grades according to the maximum average wind speed near the center of the surface layer, and the wind force near the center reaches 12 or above, which is collectively called typhoon.
Typhoons often bring strong winds, heavy rains and storm surges, which not only bring disasters to human beings, but also bring benefits to human beings. Typhoon has brought abundant fresh water resources to human beings, which is of great significance for improving fresh water supply and ecological environment. In addition, typhoons can keep the relative balance between cold and heat around the world.
Direct disasters caused by typhoons
1, gale
The wind speed of typhoons is mostly above 17m/s, even above 60m/s ... According to the measurement, when the wind reaches 12, the wind pressure per square meter on the plane perpendicular to the wind direction can reach 230kg. Therefore, when a super typhoon comes, strong winds and the huge waves caused by them can throw up or even smash coastal ships; It is also enough to destroy or even destroy buildings, bridges and vehicles on land.
2. Heavy rain
When the typhoon lands, the rainfall center can drop 100 to 300 mm, or even 500 to 800 mm of heavy rain a day. The flood disaster caused by typhoon and rainstorm is fierce and destructive, and it is the most dangerous disaster.
3. Storm surge
When the typhoon moved to land, due to the typhoon's strong wind force and low air pressure, the sea water piled up strongly towards the coast, the tide level soared, and the water waves flooded the coast, resulting in the overflow of the tide, the breakwater, the destruction of houses and various building facilities, the flooding of towns and farmland, and a large number of casualties and property losses.