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 a fascinating phenomenon called 'urban heat islands.' This refers to the fact that cities are often significantly warmer than surrounding rural areas. The primary cause is the replacement of natural surfaces with materials like concrete and asphalt, which absorb and retain heat during the day and release it slowly at night. Additionally, waste heat from vehicles, air conditioners, and industrial processes adds to the effect. Vegetation, which provides shade and releases moisture through transpiration, is often scarce in dense urban areas. Interestingly, the intensity of an urban heat island can vary within a city itself. Parks and green spaces tend to be cooler, while densely built commercial districts can be several degrees hotter. This temperature difference influences energy consumption, as people use more air conditioning, and it also affects air quality, contributing to the formation of ground-level ozone. Urban planners are now exploring solutions like green roofs and reflective materials to mitigate these effects.