Nghe TOEFL

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Narrator: Listen to part of a lecture in an environmental science class. Professor: Today we're going to talk about urban heat islands, a phenomenon where cities are significantly warmer than surrounding rural areas. This happens because concrete, asphalt, and buildings absorb and re-emit solar heat more than natural landscapes like forests or fields. Also, waste heat from vehicles and air conditioners adds to the effect. One surprising factor is the lack of vegetation. Trees and green spaces provide shade and release moisture through transpiration, which cools the air. In cities, we've replaced these with impervious surfaces that trap heat. But here's an interesting twist: not all cities experience the same intensity. Coastal cities, for example, often have milder heat islands due to sea breezes. And the layout matters too—narrow streets with tall buildings can trap heat, while wider, greener boulevards can reduce it. So, when planners design new developments, they might consider planting more trees or using reflective materials on roofs. These are simple but effective measures.