Nghe TOEFL

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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, like soil and vegetation, with materials such as concrete and asphalt, which absorb and retain heat during the day and release it slowly at night. Another factor is waste heat from buildings, vehicles, and industrial processes. The lack of vegetation reduces shade and evapotranspiration, which would otherwise cool the air. Interestingly, the effect is not uniform across a city. Dense downtown areas with tall buildings and narrow streets can trap heat, while parks and tree-lined neighborhoods tend to be cooler. To mitigate this, some cities are implementing green roofs, planting more trees, and using reflective paving materials. These strategies not only lower temperatures but also reduce energy consumption for air conditioning. However, implementing them requires careful planning and investment. So, what are the primary causes of the urban heat island effect?