การฟัง TOEFL

🎧 บทถอดเสียง

Listen to part of a lecture in an environmental science class. Professor: Today we're going to talk about urban heat islands, and why cities tend to be warmer than surrounding rural areas. One major factor is the replacement of natural surfaces with materials like concrete and asphalt. These materials absorb and re-radiate solar heat more effectively than vegetation does. Additionally, cities generate their own heat through vehicles, air conditioning, and industrial processes. But here's an interesting point: not all urban areas experience the same intensity of the heat island effect. Parks and green spaces, for example, can be several degrees cooler than densely built-up neighborhoods. This is partly due to evapotranspiration from trees and grass, which cools the air. Also, building height and street layout can affect air circulation, trapping heat in some areas. So, when city planners think about mitigating this effect, they often consider increasing green spaces and using reflective roofing materials. But there's a trade-off—sometimes these solutions require significant upfront investment. Any questions?