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 the surrounding rural areas, a phenomenon known as the urban heat island effect. This happens because buildings, roads, and other infrastructure absorb and re-emit the sun's heat more than natural landscapes do. For example, concrete and asphalt have high thermal mass, meaning they store heat during the day and release it slowly at night. In contrast, vegetation and soil have higher albedo and use evapotranspiration to cool the air. The temperature difference can be as much as 5 to 10 degrees Celsius, especially during the evening. This effect has significant implications for energy consumption, as people use more air conditioning in hotter urban areas. Additionally, it can exacerbate health issues during heatwaves. To mitigate this, cities are adopting strategies like green roofs, reflective pavements, and increasing urban tree cover. These measures not only lower temperatures but also improve air quality and reduce stormwater runoff.'