托福听力

🎧 听力原文

Listen to part of a lecture in an environmental science class. The professor is discussing the phenomenon of urban heat islands. 'Today we'll talk about urban heat islands, where cities experience higher temperatures than surrounding rural areas. This happens because materials like concrete and asphalt absorb and re-emit heat more than natural vegetation. Also, waste heat from vehicles and buildings adds to the effect. Now, one interesting mitigation strategy is the use of green roofs. These are rooftops covered with plants and soil. Green roofs help cool the air through evapotranspiration, where plants release water vapor. They also provide insulation, reducing the need for air conditioning. Another strategy is increasing albedo, or reflectivity, of surfaces. For example, painting rooftops white can reflect sunlight instead of absorbing it. Studies show that a combination of these strategies can reduce city temperatures by several degrees. However, implementation costs can be high, and maintenance requires effort. Despite this, many cities are adopting them because the long-term energy savings and comfort benefits outweigh the initial expenses.'