臺風(fēng)-龍卷風(fēng)的ppt

1、2021/3/111 Content HurricaneTornadoTyphoon 2021/3/112 Forms Measures Definition 2021/3/113 Whats the definition ? 2021/3/114 Hurricane and Typhoon Same : both of them are a special kind of tropical cyclone , and a storm system. Different : happen in different places ,so they have different name. Hur

2、ricane : occur in North Atlantic Ocean, the Caribbean Sea ,the Gulf of Mexico , or the Northeast Pacific Ocean Typhoon: Northwest Pacific Ocean west of the International Date Line 2021/3/115 2021/3/116 six main requirements for hurricane to form and develop: . sufficiently warm sea surface temperatu

3、res . atmospheric instability . high humidity in the lower to middle levels of the troposphere . enough Coriolis force(地球自轉(zhuǎn)偏向力地球自轉(zhuǎn)偏向力) to develop a low pressure center . a pre-existing low level focus or disturbance . low vertical wind shear 2021/3/117 2021/3/118 The eye of hurricane The eye, is an

4、area of relative calm (and lowest atmospheric pressure) at the center of circulation. The eye is often visible in satellite images as a small, circular, cloud-free spot. Surrounding the eye is the eyewall, an area about 16 kilometres to 80 kilometres wide in which the strongest thunderstorms and win

5、ds circulate around the storms center. 2021/3/119 Hurricane Categories Category one - Winds 74-95 mph. Category two - Winds 96-110 mph. Category three - Winds 111-130 mph. Category four - Winds 131-155 mph. Category five - Winds greater than 155 mph. 2021/3/1110 2021/3/1111 The definition of Tornado

6、 A tornado is a violent, dangerous, rotating column of air that is in contact with both the surface of the earth and a cumulonimbus(積雨積雨 云云) cloud or, in rare cases, the base of a cumulus cloud. 2021/3/1112 Place：most frequently in the United States east of the Rocky Mountains Time: spring and summe

7、r Forms : multiple-vortex tornado waterspout landspout 2021/3/1113 A change in wind direction and increase in wind speed an invisible, horizontal spinning effect in the lower atmosphere raising air within the thunderstorm updraft tilts the rotating air from horizontal to vertical rotation（ 2-6 miles

8、 wide ） rotating wall cloud a strong tornado develops 2021/3/1114 What should we do ？ environmental clues make a family plan Before the storm have frequent drills listen to radio and TV 2021/3/1115 If a Warning is issued or if threatening weather approaches: In a home or building, move to a pre- designated shelter, such as a basement. If an underground shelter is not available, move to an interior room or hallway on the lowest floor and get under a sturdy piece of furniture.