Unit 4 Natural disasters 自然灾害 ppt课件-（2019）新人教版高中英语必修第一册.pptx

1、Tsunami A tsunami is a train of gigantic waves that occur after an earthquake or volcanic eruption. They can be as high as 30 meters or ten feet, travel as fast as a jet plane and go as far inland as 2 kilometers or 1 miles. Most tsunamis happen in the Pacific. Mudslides Mudslides are fast moving la

2、ndslides that occur after heavy rains. They are rivers of mud.They can destroy and kill everything in their path.Earthquakes Earthquakes are caused by the movement of the earths plates, which lie under the surface of the earth. Earthquakes occur suddenly. 4 out of 5 earthquakes take place in the Pac

3、ific Rim.Avalanche An avalanche An avalanche is a like a mudslide except it is made up of snow and ice. They occur in the mountains after fresh snowfalls and can travel at 80 miles an hour or 128 kilometers per hour.Drought DroughtDrought: A drought occurs when there : A drought occurs when there ha

4、s not been enough rain so that crops and has not been enough rain so that crops and plants can grow. Farm animals die and plants can grow. Farm animals die and people dont have enough to eat.people dont have enough to eat.Forest Fires Forest fires are fires that burn in forest areas. Lightning can s

5、tart them but usually careless people do. There are 100,000 fires in the US every year. They can travel at 14 miles an hour or 23 kilometers an hour and will destroy everything as they move. Drought and hot weather are also responsible for many fires.Blizzards Blizzards are severe snowstorms with ve

6、ry high winds, extremely low temperatures, and poor or no visibility. They are especially dangerous for travelers who may get stuck in their cars and could suffer from hypothermiaTyphoons & Cyclones Typhoons are rotating tropical storms like hurricanes, but they occur in the north-west Pacific Ocean

7、 near Hawaii and Asia. Their winds can reach 200 miles per hour/320 kilometers per hour. Cyclones are similar storms in the Indian Ocean. They both have torrential rains and storm surges- causing massive flooding.Floods Floods are one of the worst natural disasters and cost the most money. They occu

8、r when storms cause rivers to overflow or by high tides. They cause enormous damage and loss of life.Volcanoes Volcanoes are explosions that happen from openings in the earths surface. Most volcanoes are located in the Pacific Rim. When volcanoes erupt, they spew magma, lava, and ash. There are betw

9、een 1,300 to 1,500 volcanoes on earth.Tornadoes A A tornadotornado is a spinning tube of air that touches the ground and a cloud above. They usually travel only a few miles but can destroy everything in their wake.The US has 1200 a year- more than anywhere else in the world.Hurricanes Hurricanes are

10、 strong tropical storms with Hurricanes are strong tropical storms with high winds and heavy rain that develop in the high winds and heavy rain that develop in the Atlantic Ocean. Each hurricane has a boys or Atlantic Ocean. Each hurricane has a boys or girls name. They cause tremendous damage girls

11、 name. They cause tremendous damage when they hit land. They occur from June when they hit land. They occur from June until November in the US.until November in the US.Other Disasters Heat waves- temperatures over 38C. Or 100F for an extended period of time Hailstorms- round balls of frozen rain- ca

12、n destroy crops Epidemics- fast spreading diseases- some serious others often fatal such as Ebola Wildfires- out of control fires in inhabited areas- destroy houses and crops Thunderstorms- lighting can cause fires and kill peopleWhat doesnt belong?earthquakeearthquakefogtsunami noisewindshakingRich

13、ter ScaleDouble click on words.What doesnt belong?tsunamitsunamilightninghigh wavestornadofiresjet speedearthquakesClick on the words.Name the natural disasterName the natural disaster.Describe it briefly.Describe it briefly.ThenThenCHECKCHECKtsunamiCHECKearthquakeCHECKdroughtCHECKavalancheCHECKblizzardCHECKmudslideCHECKvolcanoCHECKforest fireCHECKfloodJapanCHECKtyphoonCHECKtornadoFloridaCHECKhurricane