Reading & Writing: Fill in the Blanks 练习测试 3

Cities are often several degrees warmer than the countryside around them, a pattern known as the urban heat island effect. The gap is usually largest at night, because asphalt, brick and concrete heat during the day and release it slowly after sunset. Dark roofs make the problem worse, do narrow streets that trap warm air between tall buildings. The consequences beyond discomfort. During heatwaves, hospital admissions rise among older residents, and the demand for air conditioning can local power networks, causing blackouts at exactly the moment when cooling is most needed. Planners have several ways to respond. Planting street trees and painting roofs white can lower surface temperatures, green roofs help to insulate the buildings beneath them. These measures are not a one-off solution, however. Young trees need regular watering in their first summers, and reflective paint loses much of its benefit as dust on its surface. Cities that budget for maintenance from the start are therefore more likely to see lasting results.

Why Cities Run Hot