甘肃省沙尘暴现象 ppt解说词及演讲稿 英语版

甘肃省沙尘暴现象 ppt解说词及演讲稿 英语版（共1篇）

甘肃省沙尘暴现象 ppt解说词及演讲稿 英语版 篇1

It‘s our honor to stand here to give a speech.Our topic is about the sandstorm phenomena in Gansu Province.And it will be divided into two parts.The former part will be talked by Joanna.The latter part is Cansilys task.Now let’s begin.Ok, since I have study in Gansu Province, I have gone through sandstorms many times.Maybe everybody here is very familiar with it.But I want to show the scientific definition of it.Sandstorm is a meteorological phenomenon commonly found in arid and semi-arid regions.It is resulted from convection currents created by intensive heating of the ground.These currents can create wind up to 120km/h and appear as a solid wall of dust as much as 1,525m high which blow over a long distance.And sandstorm is a kind of climatic hazard.It was found in areas like Sahara Desert in North Africa, Central Australia, Southwest of USA, Central Asia and Northwest China including Gansu.And then we will see its actuality in this province.The characteristic includes two aspects.One is about time, and another is about space.First, time distribution features.This is the table about the sandstorm rate in the four seasons a year in Gansu province published in 2012.From this table, we can see that the rate in spring is the largest as 54.30% in the whole province.And it is the smallest as 7.45% in autumn.And the rate in summer is larger than it in winter.Generally speaking, the four seasons’ distribution features are almost as same as the average annual characteristics.So we can conclude it as maximum in spring, minimum in autumn, and the number in summer is larger than it in winter.And then, space distribution features.This is the fig about the sandstorms day’s average distribution in Gansu Province.Gansu Province is located in mid-latitude areas in northwest China, away from the sea.Gansu Province is surrounded by many deserts and plateaus, such as Loess plateau to its east, Gobi and Taklimakan deset to its west, Mongolian Plateau to its north and so on.It is known as a typical continent climate with dry climate,low rainfall and large evaporation.From the spatial distribution, the sandstorms occurrence times in the southern foothill of Qilian Mountains are less than it in the northern foothill.The area between the edge along the Badain Jaran Desert and the Tengger Desert is sandstorms multiple place.Minqin is the place where most andstorm occurred in Gansu Province.Wuwei is less than it as the secondary.So, we can conclude the times are decreasing from northeast to southwest.Now lets see the next part, the reason of the sandstorms.Maybe in our opinion, it can be divided into three parts.First, the special geographic position and landform.Second, the warm and dry weather condition in spring and the constantly moving cold winds toward east and south.Third, is changing the land-cover artificially.First, the special geographic position and landform.Gansu is surrounded by big desert and plague.It provides abundant sand resource for frequent sandstorms occurrence.More closer the distance is, more frequent the times are.There are many sandstorms in Minqin mainly because it is near the Badain Jaran Desert and the Tengger Desert.Second, the warm and dry weather condition in spring and the constantly moving cold winds toward east and south.In one hand, dry weather is the most fundamental natural environmental factors of sandstorm occurrencein Gansu Province.Gansu is a dry and thirsty province.The annual precipitation is less than 250mm.And it is very changeable;almost focus on July and August.Every spring must go through the low rainfall and large evaporation.On the other hand, strong wind is the dynamic factor of sandstorm in Gansu Province.The cold air which causes the sandstorms comes from the strong cold pressure between the northwestern Mongolian plateau and Novosibirsk.Dry weather causes uncovered ground.And plus the strong wind, there will be more sandstorms here.Third, changing the land-cover artificially.This is the most fundamental and important reason.Overgrazing, excessive land reclamation, excessive firewood and improper use of water resource.We see the overgrazing firstly.With the development of economy, there are more and more livestock on the grassland.But the grassland cannot undertake those bigger crowds.The grass is becoming less and less and the land is uncovering gradually.There will be more sands.And then there will be more sandstorms.Next, is excessive land reclamation.The same to the above.There is more population on the grassland.So it needs more grain.The reclamation becomes the most effective way to solve this problem.And then the new origin of a sandstorm comes into being.The third, excessive firewood.More livestock and more population need more endings.But we should pay some attention that the land used for grass for animal, grain for people and firewood can add up to a surprising lager number.Those uncovered land not only form a new sand resource, but also Increase air speed.The aftermath is also sandstorms.The last, improper use of water resource.Gansu is an unwatered province.And there are water wasted by us.Thus, the water shortage province is more short for water.The result is that plants are dying.The more sever sandstorms are brewing up in this area.So, we can conclude it that it is very common that there are a few sandstorms in Gansu Province.But the fundamental cause of exacerbating sandstorm lies in people’s improper behavior.We think that we should take this responsibility to focus on the importance of sandstorms.This is my part.Next will be shown by Cansily.Welcome.