การฟัง TOEFL

🎧 บทถอดเสียง

Narrator: Listen to part of a lecture in an environmental science class. Professor: Today we're going to talk about urban heat islands. As you know, cities tend to be warmer than surrounding rural areas. This is due to several factors. First, buildings and roads absorb and re-emit solar heat more than natural landscapes do. Second, cities generate their own heat from vehicles, air conditioners, and industrial processes. Third, the lack of vegetation reduces shade and evapotranspiration, which normally cools the air. Now, one interesting solution that has gained attention is the use of green roofs. These are rooftops covered with plants and soil. Green roofs can lower surface temperatures significantly, and they also help with stormwater management by absorbing rainfall. However, they are not a one-size-fits-all solution. For example, in very dry climates, they may require irrigation, which uses water and energy. Also, the initial installation cost is higher than that of conventional roofs. But in the long run, they can reduce energy bills by improving insulation. So, while green roofs are promising, we need to consider local conditions before recommending them broadly.