托福听力

🎧 听力原文

Listen to part of a lecture in an environmental science class. Today we're going to talk about the concept of 'urban heat islands'. This phenomenon occurs when cities are significantly warmer than surrounding rural areas. The main cause is the replacement of natural land cover with materials like concrete and asphalt, which absorb and retain heat. Additionally, waste heat from vehicles and buildings adds to the effect. One interesting aspect is the variation within a city itself. For example, parks and green spaces can be several degrees cooler than nearby dense commercial districts. This is because trees provide shade and release moisture through transpiration. However, the effectiveness of green spaces depends on their size and distribution. Small, isolated parks have a limited cooling effect, while large, connected green corridors can channel cool air into the city. Urban planners are now studying these patterns to design more climate-resilient cities. They are also considering 'cool roofs' that reflect sunlight and green roofs covered with vegetation. These strategies might reduce energy consumption and improve public health. But we must remember that each city has unique geography and climate, so solutions need to be tailored accordingly.