托福阅读真题Official 48 Passage 3（三）

托福阅读真题Official 48 Passage 3（三）

Climate and Urban Development

For more than a hundred years,it has been known that cities are generally warmer than surrounding rural areas.This region of city warmth,known as the urban heat island,can influence the concentration of air pollution.However,before we look at its influence,let’s see how the heat island actually forms.

The urban heat island is due to industrial and urban development.In rural areas,a large part of the incoming solar energy is used in evaporating water from vegetation and soil.In cities,where less vegetation and exposed soil exist,the majority of the Sun’s energy is absorbed by urban structures and asphalt.Hence,during warm daylight hours,less evaporative cooling in cities allows surface temperatures to rise higher than in rural areas.The cause of the urban heat island is quite involved.Depending on the location,time of year,and time of day,any or all of the following differences between cities and their surroundings can be important:albedo(reflectivity of the surface),surface roughness,emissions of heat,emissions of moisture,and emissions of particles that affect net radiation and the growth of cloud droplets.

At night,the solar energy(stored as vast quantities of heat in city buildings and roads)is slowly released into the city air.Additional city heat is given off at night(and during the day)by vehicles and factories,as well as by industrial and domestic heating and cooling units.The release of heat energy is retarded by the tall vertical city walls that do not allow infrared radiation to escape as readily as does the relatively level surface of the surrounding countryside.The slow release of heat tends to keep nighttime city temperatures higher than those of the faster-cooling rural areas.Overall,the heat island is strongest(1)at night when compensating sunlight is absent;(2)during the winter,when nights are longer and there is more heat generated in the city;and(3)when the region is dominated by a high-pressure air pressure(atmospheric pressure)is the pressure exerted by the mass of air above a given place area with light winds,clear skies,and less humid air.Over time,increasing urban heat islands affect climatological temperature records,producing artificial warming in climatic records taken in cities.This warming,therefore,must be accounted for in interpreting climate change over the past century.

The constant outpouring of pollutants into the environment may influence the climate of the city.Certain particles reflect solar radiation,thereby reducing the sunlight that reaches the surface.Some particles serve as nuclei upon which water and ice form.Water vapor condenses onto these particles when the relative humidity is as low as 70 percent,forming haze that greatly reduces visibility.Moreover,the added nuclei increase the frequency of city fog.

Studies suggest that precipitation may be greater in cities than in the surrounding countryside;this phenomenon may be due in part to the increased roughness of city terrain,brought on by large structures that cause surface air to slow and gradually converge.This piling up of air over the city then slowly rises,much like toothpaste does when its tube is squeezed.At the same time,city heat warms the surface air,making it more unstable,which enhances rising air motions,which,in turn,aids in forming clouds and thunderstorms.This process helps explain why both tend to be more frequent over cities.

On clear still nights when the heat island is pronounced,a small thermal low-pressure area forms over the city.Sometimes a light breeze—called a country breeze—blows from the countryside into the city.If there are major industrial areas along the outskirts,pollutants are carried into the heart of town,where they tend to concentrate.Such an event is especially probable if vertical mixing and dispersion of pollutants are inhibited.Pollutants from urban areas may even affect the weather downwind from them.

Question 5 of 14

Select the TWO answer choices that describe ways mentioned in paragraphs 2 and 3 in which solar energy affects urban and rural areas.To receive credit,you must select TWO answers.

A.Solar energy causes evaporation from vegetation and soil,producing a cooling effect.

B.Solar energy stored as heat is lost quickly when tall city buildings guide hot air up and away from the surface.

C.Solar energy increases the atmospheric pressure over open areas.

D.Solar energy is stored up in buildings and roads and emitted as heat during the night.

正确答案：AD

题目详解

题型分类：事实信息题

原文定位：1.In rural areas,a large part of the incoming solar energy is used in evaporating water from vegetation and soil。

2.At night,the solar energy(stored as vast quantities of heat in city buildings and roads)is slowly released into the city air。

选项分析：

A选项：描述能量引起蒸发和第一个定位点说在农村地区，大部分的太阳能用于从植被和土壤蒸发相对应，正确。

D选项：描述“太阳能被储存在高楼里，然后又被释放”与原文第二个定位点说的“夜间（存储在城市建筑物和道路的大量热量）太阳能正在缓慢释放到城市的空气中”相对应，正确。

B选项：与原文相矛盾。原文中城市中的建筑会阻碍热量被植被吸收，并且在晚上会释放热量，使得城市温度上升。因此错误。

C选项：原文中并未提及，属于无中生有。因此错误。

Question 6 of 14

Paragraph 3 supports which of the following claims about the interpretation of temperature records?

A.The climate may not be warming as much as the increase of temperatures recorded in cities appears to suggest.

B.Records show that the increase in urban heat islands has had a significant warming effect on the global climate.

C.During most of the past century,temperature records have been misinterpreted.

D.Scientists will not be able to account for climate change over the past century until they learn more about the urban heat island.

正确答案：A

题目详解

题型分类：事实信息题

原文定位：定位Over time,increasing urban heat islands affect climatological temperature records,producing artificial warming in climatic records taken in cities.This warming,therefore,must be accounted for in interpreting climate change over the past century.随着时间的推移，增加的城市热岛效应影响气候温度记录,在城市中产生了人工气候变暖气候记录。因此，这种变暖必定是解释气候变化在过去的一个世纪的原因。意思就是说这种温度记录不是纯粹的温度记录，是加入了人工气候后变暖的，那么我们过去几个世纪所研究的温度都是既包括自然温度又有人工气候的。

选项分析：

A选项：气候并没有温度记录显示的那么热。正确，目前的气候是有人工气候掺合在内的，所以原本的气候没有那么热。

B选项：记录表明城市热岛温度的增加对全球气候的变热现象有着重要的影响。

C选项：在过去的一个世纪里，温度记录都被错误的解读了。文中并未提及。属于无中生有。因此错误。

D选项：科学家们直到了解了城市热岛现象后才能够解释气候变化的原因