Nghe TOEFL

🎧 Bản ghi âm

Narrator: Listen to part of a lecture in an environmental science class. Professor: Today we're going to talk about urban heat islands. You know that cities tend to be warmer than surrounding rural areas, sometimes by several degrees. Why is that? Well, one major factor is the materials we use to build. Concrete and asphalt absorb and retain heat during the day and release it slowly at night. Another factor is the lack of vegetation. Trees and green spaces provide shade and release moisture through transpiration, which cools the air. In cities, we replace those natural surfaces with roofs and roads. But here's an interesting solution: green roofs. These are rooftops covered with plants and soil. Research shows that green roofs can significantly reduce the surface temperature of a building, and they also help with stormwater management by absorbing rainwater. However, they're not a one-size-fits-all solution. Their effectiveness depends on climate, the types of plants used, and the building's structure. Older buildings may not support the extra weight. So, while green roofs are promising, we need to consider multiple factors before implementing them on a large scale.