新托福听写训练 第18期

Listen to a talk given by a professor of meteorology.

First of all, let's look at why temperatures tend to be higher in city than in the rural area. This happens because almost 50% of the urban areas are comprised of hard surfaces like paved street, parking lot, buildings and roof tops. As a result, any amount of rainfall is quickly repelled¹ by this service and carried away by storm drains and gutters². Especially water just does not have the chance to stand around until evaporate and during the process of evaporation⁴ that heat is removed from the air. So in cities where there is less evaporation temperatures will be higher and of course there are also be issue of added heat coming from building heating system, from industry, cars even human body. Even within the city itself, temperatures can vary significantly. For example, in winter streets that get a lot of use will be 2 or 3 degrees warmer than less travel streets.

In place where car sits for a while like a spotlight⁵ can be another 3 degrees warmer. On the other hand, low spots in the city where cold air collect will much colder than higher places. Rain and snowfall are also affected⁶ by urbanization. Cities tend to quite less snowfall than the surroundings of countryside because of warmer temperatures in the city. But rainfall in the city can be 5 to 10 percent higher. That happens because of 2 factors. First the warmer city temperature, second the larger number of dust particles in the urban air. It seems dust particles are important requirement for condensation⁷. Water vapor³ in the atmosphere is able to change to the liquid by planning to dust particles suspended in the air. So where there is the higher number of dust particles, condensation takes place more easily. That's why the fogs and clouds are usually more frequent around the city. Once condensation takes place, the rainfall is not far behind. In the London area for example, thunderstorms can produce 30 percent more rainfalls than the surrounding countryside. Some urban climatologists go so far as they argue that they can see a pattern increasing the rainfall during the workweek. They believe rainfalls amounts are small around weekend because dust particles generated by cars and factories are reduced.

1 repelled   

v.击退( repel的过去式和过去分词 )；使厌恶；排斥；推开

参考例句：

• They repelled the enemy. 他们击退了敌军。 来自《简明英汉词典》
• The minister tremulously, but decidedly, repelled the old man's arm. 而丁梅斯代尔牧师却哆里哆嗦地断然推开了那老人的胳臂。 来自英汉文学 - 红字

2 gutters   

（路边）排水沟( gutter的名词复数 )； 阴沟； （屋顶的）天沟； 贫贱的境地

参考例句：

• Gutters lead the water into the ditch. 排水沟把水排到这条水沟里。
• They were born, they grew up in the gutters. 他们生了下来，以后就在街头长大。

3 vapor   

n.蒸汽，雾气

参考例句：

• The cold wind condenses vapor into rain.冷风使水蒸气凝结成雨。
• This new machine sometimes transpires a lot of hot vapor.这部机器有时排出大量的热气。

4 evaporation   

n.蒸发，消失

参考例句：

• Be careful not to lose too much liquid by evaporation.小心不要因蒸发失去太多水分。
• Our bodies can sweat,thereby losing heat by evaporation.我们的身体能出汗，由此可以蒸发散热。

5 spotlight   

n.公众注意的中心，聚光灯，探照灯，视听，注意，醒目

参考例句：

• This week the spotlight is on the world of fashion.本周引人瞩目的是时装界。
• The spotlight followed her round the stage.聚光灯的光圈随着她在舞台上转。

6 affected   

adj.不自然的，假装的

参考例句：

• She showed an affected interest in our subject.她假装对我们的课题感到兴趣。
• His manners are affected.他的态度不自然。

7 condensation   

n.压缩，浓缩；凝结的水珠

参考例句：

• A cloud is a condensation of water vapour in the atmosphere.云是由大气中的水蒸气凝结成的。
• He used his sleeve to wipe the condensation off the glass.他用袖子擦掉玻璃上凝结的水珠。