TOEFL Listening

🎧 Listening Transcript

Narrator: Listen to part of a lecture in an environmental science class. Professor: Today we're talking about urban heat islands. Cities tend to be warmer than surrounding rural areas because of concrete, asphalt, and buildings that absorb and re-radiate heat. But there are strategies to mitigate this effect. One common approach is increasing vegetation, like planting trees on streets and creating green roofs. Trees provide shade and release moisture through transpiration, which cools the air. However, a lesser-known strategy is using reflective materials on rooftops and pavements. These so-called 'cool roofs' reflect more sunlight and absorb less heat than standard dark materials. In fact, studies show that a white roof can be up to 30 degrees cooler than a black one on a sunny day. Cool pavements work similarly. They're made with lighter-colored materials or special coatings. While these methods are effective, they require initial investment and maintenance. But over time, they reduce energy costs for cooling buildings, and they also improve air quality by reducing smog formation. So, in urban planning, a combination of green and reflective strategies often yields the best results.