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IELTS-style academic reading: True/False/Not Given and summary completion
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Independent practice in the IELTS Academic reading style, not an official test: read a passage about why cities stay warm at night, then answer True/False/Not Given and summary completion questions.
Why cities stay warm after dark
On a still summer evening, someone cycling from the centre of a large city out into the surrounding countryside may notice that the air becomes cooler within a short distance. This contrast, known as the urban heat island effect, has been observed in cities on every inhabited continent. Interestingly, the difference between town and country is often greatest not in the afternoon, when the sun is strongest, but several hours after sunset.
The main cause lies in the materials from which cities are built. Asphalt roads and dark roofs absorb much of the sunlight that falls on them, while brick, stone and concrete store heat during the day and release it slowly at night. In the countryside, by contrast, much of the ground is covered by soil and vegetation. Plants draw water from the soil and release it through their leaves, and this evaporation uses energy that would otherwise warm the air. When fields and woods are replaced by paved surfaces, this natural form of cooling largely disappears.
The shape of a city matters as well. Where tall buildings line narrow streets, much of the heat given off by walls and roads at night is absorbed by neighbouring buildings instead of escaping to the open sky. The same buildings can slow the wind that would otherwise carry warm air away. Cities also produce heat of their own: engines, factories and air-conditioning units all release warmth into the streets, so on hot days, when air conditioners are working hardest, they add to the very problem they are designed to solve.
Warm nights are more than an inconvenience. Many people find it difficult to sleep well when their bedrooms stay warm, and several poor nights in a row can leave them less able to cope with the heat during the day. Older people, young children and those who are already unwell are generally considered the most vulnerable during long spells of hot weather. Higher temperatures also increase the demand for electricity for cooling, which can place extra pressure on power networks.
Fortunately, the effect can be reduced. Planting trees is one of the most widely recommended measures, because trees both shade the ground and cool the air around them. Roofs can be covered with plants, or painted in light colours that reflect sunlight rather than absorb it, and some cities have experimented with lighter-coloured pavements. Parks, rivers and fountains can also create pockets of cooler air.
None of these solutions is perfect, however. Trees need space, regular care and, in dry regions, a reliable supply of water, and their roots can damage pipes and pavements if species are poorly chosen. Highly reflective surfaces may bounce sunlight onto nearby walls or into the eyes of people walking past. For this reason, urban planners increasingly argue that there is no single answer, and that the best combination of measures depends on the climate, the layout and the needs of each particular city.
True, False or Not Given
Do the statements agree with the information in the passage? Choose True if the statement agrees with the information, False if it contradicts the information, or Not Given if there is no information about it.
- The urban heat island effect has been recorded in only a small number of cities.
- The temperature difference between a city and the countryside is often greatest some hours after the sun has set.
- Replacing fields and woods with paved surfaces removes a natural way of cooling the air.
- In narrow streets with tall buildings, much of the heat released at night stays among the buildings.
- Air-conditioning units help to lower the temperature of the air in city streets.
- Warm nights are more dangerous for people who live alone than for people who live with others.
- Painting a roof in a light colour costs less than covering it with plants.
- Urban planners generally agree that planting trees is enough on its own to solve the problem.
Summary completion
Complete the summary of the passage. The sentences below form one summary; read them in order. Choose NO MORE THAN TWO WORDS from the passage for each answer.
- Cities are often warmer than nearby rural areas, a contrast known as the urban ___ effect.
- Brick, stone and concrete ___ heat during the day and give it out slowly at night.
- When bedrooms stay warm, many people find it hard to ___ well.
- Greater use of electricity for cooling also puts extra pressure on power ___.
- Trees are widely recommended because they ___ the ground as well as cooling the air.
- Roofs can be painted in light colours that ___ sunlight instead of absorbing it.
- However, in dry regions trees depend on a reliable supply of ___.
- Very reflective surfaces may also send sunlight into the ___ of passers-by.
Answer key
True, False or Not Given
- b) FalseThe passage says it has been observed in cities on every inhabited continent, so it is not limited to a small number.
- a) TrueThe writer says the difference is often greatest not in the afternoon but several hours after sunset.
- a) TrueWhen fields and woods are replaced by paved surfaces, the cooling caused by plants largely disappears.
- a) TrueThe heat is absorbed by neighbouring buildings instead of escaping to the open sky.
- b) FalseThey release warmth into the streets and add to the problem, so they do not cool the street air.
- c) Not GivenThe passage names older people, young children and people who are unwell, but it says nothing about people who live alone.
- c) Not GivenBoth measures are mentioned, but the passage gives no information about their cost.
- b) FalsePlanners increasingly argue that there is no single answer and that cities need a combination of measures.
Summary completion
- heat islandThe first paragraph names it the urban heat island effect.
- storeThe passage says these materials store heat during the day and release it slowly at night.
- sleepParagraph four says many people find it difficult to sleep well when their bedrooms stay warm.
- networksHigher demand for electricity can place extra pressure on power networks.
- shadeThe passage says trees both shade the ground and cool the air around them.
- reflectLight colours reflect sunlight rather than absorb it.
- waterTrees in dry regions need a reliable supply of water.
- eyesReflective surfaces may bounce sunlight into the eyes of people walking past.