托福听力

🎧 听力原文

Narrator: Listen to part of a lecture in an environmental science class. Professor: Today we're discussing the concept of 'urban heat islands.' This phenomenon occurs when cities become significantly warmer than surrounding rural areas. The main cause is the replacement of natural land cover—like vegetation and soil—with materials such as concrete and asphalt, which absorb and retain heat. Additionally, human activities, including transportation and industrial processes, generate excess heat. One key factor is the lack of trees, which normally provide shade and cool the air through evapotranspiration. Interestingly, the temperature difference can be as much as 10 degrees Fahrenheit on clear, calm nights. To mitigate this effect, some cities are implementing green roofs, planting more trees, and using reflective materials on buildings. These strategies not only reduce temperatures but also lower energy consumption for cooling. Now, why is this particularly important as global temperatures rise? Because urban populations are growing, making more people vulnerable to heat-related health issues.