托福听力

🎧 听力原文

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: dark surfaces like asphalt and rooftops absorb sunlight, buildings block wind, and human activities generate heat. However, there are ways to mitigate this effect. One common solution is planting trees, which provide shade and release moisture through transpiration. Another is using cool roofs, which are painted white or reflective colors to bounce sunlight back into the atmosphere. But these methods have limitations. For instance, trees require water and maintenance, and cool roofs may not be effective in cloudy climates. Recently, some cities have experimented with green roofs—rooftops covered with vegetation. Green roofs not only reduce heat but also manage stormwater and improve insulation. However, they are expensive to install and require structural support. So, while each strategy has benefits, cities must consider their specific climate and budget when choosing a solution.