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. "Urban areas tend to be warmer than surrounding rural areas, a phenomenon known as the urban heat island effect. This occurs because concrete, asphalt, and buildings absorb and re-emit solar heat more than natural landscapes do. Additionally, waste heat from vehicles, air conditioners, and industrial processes contributes to the warming. The temperature difference can be as much as 5 to 10 degrees Celsius on clear, calm nights. Vegetation, which provides shade and releases moisture through evapotranspiration, is often scarce in cities, further reducing cooling. To mitigate this effect, cities have implemented strategies such as green roofs, reflective pavements, and increasing tree cover. For example, a study in Los Angeles showed that planting trees and painting roofs white could reduce city temperatures by up to 3 degrees Celsius. However, these measures require significant investment and long-term planning, and their effectiveness varies by climate and city layout."