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Where did Typhoons Come from

2019-12-10  |   Editor : houguangbing  

The typhoons that affect China are mainly from the Pacific Ocean east of the Philippines, and sometimes also from the south China sea. Near the equator, the sea is hot, the evaporation is intense, a large amount of rising air is hot and humid, drawing the cold air around to take the place.

Because of the earth's rotation, the air in the northern hemisphere deflects to the right, and the cooler air coming from all sides moves towards the areas where hot and humid air is rising. The deflection to the right creates an air vortex over the ocean. This vortex moves counterclockwise and is called a cyclone. If the process of forming a vortex is repeated, the cyclone will rotate faster and wider. If the wind near the center of the cyclone reaches force 8 or above, it is called a typhoon.

The diameter of this huge air vortex ranges from several hundred kilometers to thousands of kilometers, and the height is above eight or nine kilometers. The central part is called the typhoon eye, with a diameter of 10000m to 56000m. It is surrounded by rapidly rotating air currents that form huge, thick walls of clouds, or cloud walls.

In the eye of the typhoon, the air pressure is low with slow wind and high waves because the air outside can not flow in. When the clouds are separated and thinner, the sun and moon stars are visible sometimes. But around the eye of the typhoon is the most stormy region.

Due to the guidance of the upper east wind flow and the impact of the earth's rotation, the typhoon tends to move west and north after its formation. So in China, Taiwan and southeast coastal areas bear the brunt. When the typhoon is over land, its heat and water can’t be replenished, and the friction with the ground decreases its speed, thus he impact of typhoons is limited to coastal areas and has no direct impact on inland areas.

The formation of typhoons is observable, especially with advanced meteorological observation means. According to satellite photos, researchers can know everything about the formation process, moving route and running speed of typhoons. Therefore, the meteorological department can make an accurate forecast of the typhoon at present. With the forecast, people can make full preparations in advance to avoid or reduce the damage typhoons caused.

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