Nghe TOEFL

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Listen to part of a lecture in an environmental science class. The professor is discussing the concept of urban heat islands. Professor: Today we're going to talk about urban heat islands, a phenomenon where cities are significantly warmer than surrounding rural areas. This happens mainly because of the materials used in construction, like concrete and asphalt, which absorb and retain heat more than natural landscapes. Also, cities have less vegetation, which means less shade and less cooling through evapotranspiration. Additionally, waste heat from vehicles and air conditioning units adds to the problem. The temperature difference can be as much as 10 degrees Fahrenheit on a clear night. To mitigate this, some cities are implementing green roofs, planting trees, and using reflective materials on buildings and roads. These measures not only lower temperatures but also reduce energy consumption and improve air quality. While the cost of retrofitting existing structures can be high, the long-term benefits are significant.