The city is an extraordinary processor of mass and energy and has its own metabolism. A daily input of water, food, and energy of various kinds is matched by an output of sewage, solid waste, air pollutants, energy, and materials that have been transformed in some way. The quantities involved are enormous. Many aspects of this energy use affect the atmosphere of a city, particularly in the production of heat.
In winter the heat produced by a city can equal or surpass the amount of heat available from the Sun. All the heat that warms a building eventually transfers to the surrounding air, a process that is quickest where houses are poorly insulated. But an automobile produces enough heat to warm an average house in winter, and if a house were perfectly insulated, one adult could also produce more than enough heat to warm it. Therefore, even without any industrial production of heat, an urban area tends to be warmer than the countryside that surrounds it.
The burning of fuel, such as by cars, is not the only source of this increased heat. Two other factors contribute to the higher overall temperature in cities. The first is the heat capacity of the materials that constitute the city, which is typically dominated by concrete and asphalt. During the day, heat from the Sun can be conducted into these materials and stored—to be released at night. But in the countryside materials have a significantly lower heat capacity because a vegetative blanket prevents heat from easily flowing into and out of the ground. The second factor is that radiant heat coming into the city from the Sun is trapped in two ways: (1) by a continuing series of reflection among the numerous vertical surfaces that buildings present and (2) by the dust dome, the cloudlike layer of polluted air that most cities produce. Shortwave radiation from the Sun passes through the pollution dome more easily than outgoing longwave radiation does; the latter is absorbed by the gaseous pollutants of the dome and reradiated back to the urban surface.
Cities, then, are warmer than the surrounding rural areas, and together they produce a phenomenon known as the urban heat island. Heat islands develop best under particular conditions associated with light winds, but they can form almost any time. The precise configuration of a heat island depends on several factors. For example, the wind can make a heat island stretch in the direction it blows. When a heat island is well developed, variations can be extreme; in winter, busy streets in cities can be 1.7℃ warmer than the side streets. Areas near traffic lights can be similarly warmer than the areas between them because of the effect of cars standing in traffic instead of moving. The maximum differences in temperature between neighboring urban and rural environments is called the heat-island intensity for that region. In general, the larger the city, the greater its heat-island intensity. The actual level of intensity depends on such factors as the physical layout, population density, and productive activities of a metropolis.
The surface-atmosphere relationships inside metropolitan areas produce a number of climatic peculiarities. For one thing, the presence or absence of moisture is affected by the special qualities of the urban surface. With much of the built-up landscape impenetrable by water, even gentle rain runs off almost immediately from rooftops, streets, and parking lots. Thus, city surfaces, as well as the air above them, tend to be drier between episodes of rain; with little water available for the cooling process of evaporation, relative humidities are usually lower. Wind movements are also modified in cities because buildings increase the friction on air flowing around them. This friction tends to slow the speed of winds, making them far less efficient at dispersing pollutants. On the other hand, air turbulence increases because of the effect of skyscrapers on airflow. Rainfall is also increased in cities. The cause appears to be in part greater turbulence in the urban atmosphere as hot air rises from the built-up surface.
Paragraph 1: The city is an extraordinary processor of mass and energy and has its own metabolism. A daily input of water, food, and energy of various kinds is matched by an output of sewage, solid waste, air pollutants, energy, and materials that have been transformed in some way. The quantities involved are enormous. Many aspects of this energy use affect the atmosphere of a city, particularly in the production of heat.
1. The word “enormous” in the passage is closest in meaning to
○ growing
○ frightening
○ very large
○ strictly controlled
Paragraph 2: In winter the heat produced by a city can equal or surpass the amount of heat available from the Sun. All the heat that warms a building eventually transfers to the surrounding air, a process that is quickest where houses are poorly insulated. But an automobile produces enough heat to warm an average house in winter, and if a house were perfectly insulated, one adult could also produce more than enough heat to warm it. Therefore, even without any industrial production of heat, an urban area tends to be warmer than the countryside that surrounds it.
2. The word “surpass” in the passage is closest in meaning to
○ remain below
○ be higher than
○ add to
○ come close to
3. According to paragraph 2, how soon heat from a warmed house reaches the outside air greatly affected by
○ how well the house is heated
○ how well the house is insulated
○ how many adults live in the house
○ how much sunshine the house receives
Paragraph 3: The burning of fuel, such as by cars, is not the only source of this increased heat. Two other factors contribute to the higher overall temperature in cities. The first is the heat capacity of the materials that constitute the city, which is typically dominated by concrete and asphalt. During the day, heat from the Sun can be conducted into these materials and stored—to be released at night. But in the countryside materials have a significantly lower heat capacity because a vegetative blanket prevents heat from easily flowing into and out of the ground. The second factor is that radiant heat coming into the city from the Sun is trapped in two ways: (1) by a continuing series of reflection among the numerous vertical surfaces that buildings present and (2) by the dust dome, the cloudlike layer of polluted air that most cities produce. Shortwave radiation from the Sun passes through the pollution dome more easily than outgoing longwave radiation does; the latter is absorbed by the gaseous pollutants of the dome and reradiated back to the urban surface.
4. According to paragraph 3, each of the following contributes to making urban areas warmer than the surrounding countryside EXCEPT
○ the fuel burned by motor vehicles
○ the capacity to store heat of the materials used in building a city
○ the easy flow of heat into the ground in city areas covered by vegetation
○ the repeated reflection of solar radiation back and forth among buildings
5. According to paragraph 3, why do materials in the countryside have a lower heat capacity than materials in cities do?
○ The countryside in the Sun is the only important source of heat.
○ Construction materials in the city are not as good at keeping buildings warm as they are in the countryside.
○ In the countryside the solar heat that flows into the ground flows out again quickly.
○ Countryside vegetation prevents heat from being trapped in the ground.
6. How is paragraph 3 organized?
○ It describes two factors that contribute to the increased heat of cities and then provides two causes for the second factor.
○ It describes two causes discovered in an early analysis of the increased heat of cities.
○ It describes two factors that contribute to the increased heat of cities and two other factors that work against it.
○ It describes two well-established causes of the increased heat of cities and other two whose roles are less well understood.
Paragraph 4: Cities, then, are warmer than the surrounding rural areas, and together they produce a phenomenon known as the urban heat island. Heat islands develop best under particular conditions associated with light winds, but they can form almost any time. The precise configuration of a heat island depends on several factors. For example, the wind can make a heat island stretch in the direction it blows. When a heat island is well developed, variations can be extreme; in winter, busy streets in cities can be 1.7℃ warmer than the side streets. Areas near traffic lights can be similarly warmer than the areas between them because of the effect of cars standing in traffic instead of moving. The maximum differences in temperature between neighboring urban and rural environments is called the heat-island intensity for that region. In general, the larger the city, the greater its heat-island intensity. The actual level of intensity depends on such factors as the physical layout, population density, and productive activities of a metropolis.
7.The word “configuration” in the passage is closest in meaning to
○ location
○ history
○ temperature
○ shape
8. According to paragraph 4, what can explain the substantial differences in temperature between one area and other within a well-developed heat island?
○ The overall size of the heat island that includes the two reasons
○ The intensify of the heat island that includes the two areas
○ Differences between the two areas in the general level of activity, including traffic
○ Differences between the two areas in the insulation materials used in construction
9. Paragraph 4 supports the idea that a city’s heat-island intensity would increase if
○ the city went into an economic decline and lost population
○ the city’s economy shifted from heavy industry to health care and education
○ there was an upward trend in the average age of the city’s residents
○ repair work on the streets slowed traffic throughout the city
Paragraph 5: The surface-atmosphere relationships inside metropolitan areas produce a number of climatic peculiarities. For one thing, the presence or absence of moisture is affected by the special qualities of the urban surface. With much of the built-up landscape impenetrable by water, even gentle rain runs off almost immediately from rooftops, streets, and parking lots. Thus, city surfaces, as well as the air above them, tend to be drier between episodes of rain; with little water available for the cooling process of evaporation, relative humidities are usually lower. Wind movements are also modified in cities because buildings increase the friction on air flowing around them. This friction tends to slow the speed of winds, making them far less efficient at dispersing pollutants. On the other hand, air turbulence increases because of the effect of skyscrapers on airflow. Rainfall is also increased in cities. The cause appears to be in part greater turbulence in the urban atmosphere as hot air rises from the built-up surface.
10. According to paragraph 5, surfaces in the city are generally drier than surfaces in the countryside between periods of rainfall because
○ in the city gentle rain is much more common than heavy rain
○ high temperatures in the city speed up the process of evaporation
○ in the city there are longer periods of dry weather between episodes of rain
○ rainwater in the city cannot soak into most surfaces and quickly runs off
11. The word “modified” in the passage is closest in meaning to
○ changed
○ blocked
○ increased
○ weakened
12. According to paragraph 5, which of the following is a factor responsible for the greater air turbulence in urban environments?
○ The high speed of the winds travelling above cities
○ The greater rainfall totals recorded in cities
○ Attempts to reduce urban air pollution
○ The effects of tall buildings on airflow
Paragraph 4: Cities, then, are warmer than the surrounding rural areas, and together they produce a phenomenon known as the urban heat island. Heat islands develop best under particular conditions associated with light winds, but they can form almost any time. ■The precise configuration of a heat island depends on several factors. ■For example, the wind can make a heat island stretch in the direction it blows. ■When a heat island is well developed, variations can be extreme; in winter, busy streets in cities can be 1.7℃ warmer than the side streets. ■Areas near traffic lights can be similarly warmer than the areas between them because of the effect of cars standing in traffic instead of moving.
The maximum differences in temperature between neighboring urban and rural environments is called the heat-island intensity for that region. In general, the larger the city, the greater its heat-island intensity. The actual level of intensity depends on such factors as the physical layout, population density, and productive activities of a metropolis.
13. Look at the four squares [■] that indicate where the following sentence could be added to the passage.
Another possibility is for the heat island to be stretched along the course of major rivers, since large waterways typically have a warming effect on the air directly above them.
Where would the sentence best fit?
14. Directions: An introductory sentence for a brief summary of the passage is provided below. Complete the summary by selecting the THREE answer choices that express the most important ideas in the passage. Some answer choices do not belong in the summary because they express ideas that are not presented in the passage or are minor ideas in the passage. This question is worth 2 points.
Cities create climatic conditions of their own through their physical structure and urban activities.
●
●
●
Answer Choices
○ The amount of heat produced in a city will be reduced when cities use the heat from cars to warm homes.
○ The built-up landscape of the city readily becomes a heat island, with greater water runoff and special climatic conditions such as low relative humidity and increased air turbulence.
○ The materials from which cities are built and the effects of pollution domes help make urban areas warmer than rural areas.
○ Cities tend to be warmer than their surrounding areas, in part because they produce heat by burning fuel for heating, powering vehicles, and industrial production.
○ In most cities, the heating that results from solar radiation is intensified by carbon dioxide, a gas that is present at very high concentrations in cities’ atmospheres.
○ During periods without rainfall, the air in cities heats up and causes winds to slow down, with the result that pollutants are not dispersed.
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城市气候
城市是一个物质和能量的巨大处理器，拥有自己的新陈代谢。每天输入水、食物和各种各样的能量，相应的输出废水、废气、固体垃圾、废能和某种程度上已经变形的材料。这个过程中的物质转移量异常的大。这种能源的消耗在很多方面影响城市的气候，尤其是产生热量方面。
冬天城市所产生的热量可以达到或超过其从太阳那里接收的热量。所有用来供暖的热量最后都扩散至周围的空气中，这个过程在那些隔热效果差的房屋里进行得最快。一辆汽车所产生的热量足以为一个普通的房屋供暖，如果房屋隔热效果好，一个成年人产生的热量就足以让其保暖了。因此，即使没有任何工业产热，城市地区也会比它周围的乡村地区更暖和。
燃料的燃烧，比如汽车燃料，并不是这种热量增加的唯一来源。另外两个因素导致了城市较高的整体温度。第一个是建造城市的材料的热容，主要典型材料是沥青和混凝土。白天，来自太阳的热量传入到这些物质当中并储存起来，在晚上被释放。但是在乡村储存能量的物质热容更低，因为植被会阻止热量轻易流入和流出地面。第二个因素是从太阳到城市的辐射热以两种形式被拦截了：（1）通过大量建筑的垂直表面的不断反射（2）通过尘埃，即大多数城市中受污染空气组成的云状物质。来自太阳的短波辐射比长波辐射要更容易穿过污染层；后者被这层物质中的气体污染物所吸收，然后重新辐射到城市的表层。
城市要比它周围的乡村地区热，同时它们产生了被称为城市热岛的现象。热岛效应在特殊条件下尤其是有微风时最明显，但是却几乎在任何时候都能形成。热岛的准确状态决定于好几个因素。比如风能在它出现的地方形成一个区域性的热岛。当一个热岛完全形成时，温度变化可能会非常极端；在冬天，繁忙的街道可能要比旁边的街道温度高1.7℃。那些红绿灯附近的地区同样要比红绿灯之间的地区要暖和，因为汽车停止时候的热效应要比运动时明显。城市周边和乡村环境的最大不同是地区热岛效应的程度。一般来讲，城市越大，热岛效应的程度就越强。实际上热岛效应的程度取决于实际布局、人口密度、和城市的生产活动等诸多因素。
在大都市里表面大气之间的关系产生了一系列特殊的气候特征。首先，湿气的存在与否受到了城市表层特殊性质的影响。由于水无法穿过大多数城市建筑，即使是很小的雨也会立即从屋顶、街道和停车场流到地下。这样城市表层包括其空气在雨季的间歇期就会比较干燥；由于蒸发的冷却过程缺少水分，相对湿度通常也很低。气流会因为城市建筑的摩擦而改变。这种摩擦会降低风速，使得气体扩散污染物的效率降低。另一方面，湍流也会因为摩天大楼的影响而增加。城市降雨也增加了。其原因部分在于从地表上升的热空气所造成的城市大气中的更大湍流。
