การฟัง TOEFL

🎧 บทถอดเสียง

Listen to part of a lecture in an environmental science class. Professor: Today we're going to talk about the concept of 'urban heat islands' and some surprising solutions. As cities grow, they replace natural surfaces with concrete and asphalt, which absorb and retain heat. This makes cities significantly warmer than surrounding rural areas. But here's an interesting twist: recent studies suggest that increasing albedo—basically, making surfaces more reflective—can reduce temperatures. For example, painting rooftops white can reflect sunlight and lower cooling energy use. However, there's a catch. In some cities, especially those with cold winters, white roofs can increase heating demands in winter, because they reflect sunlight away during months when solar warmth is beneficial. So the effectiveness of white roofs depends on climate. Another solution is planting trees, which provide shade and release moisture. Trees also absorb carbon dioxide, so they have multiple benefits. But trees require water and maintenance, which can be costly. So, which solution is best? It really depends on local conditions, including climate, infrastructure, and budget. Now, let's consider a specific case study...