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. One major cause is the replacement of natural surfaces with asphalt and concrete, which absorb and retain heat. Another factor is the lack of vegetation, since trees and plants provide shade and release moisture through transpiration, cooling the air. Additionally, waste heat from vehicles, air conditioners, and industrial processes adds to the thermal output. Interestingly, the intensity of the heat island effect can vary with city size and layout. For example, a compact city with narrow streets and tall buildings might trap heat more effectively than a sprawling one with open spaces. But there are mitigation strategies. Green roofs, which are covered with vegetation, can reduce rooftop temperatures and improve insulation. Planting more street trees and using reflective materials on pavements can also help. However, these solutions require careful planning and investment. Some cities have already implemented such measures and reported noticeable temperature drops. So, while the problem is serious, there are practical steps we can take.