TOEFL Listening

🎧 Listening Transcript

Listen to part of a lecture in an environmental science class. The professor is discussing the concept of urban heat islands. Professor: Today we're going to talk about urban heat islands. This phenomenon occurs when cities experience higher temperatures than the surrounding rural areas. Why is this? Well, one major factor is the materials used in construction. Concrete and asphalt absorb and retain heat from the sun much more effectively than natural surfaces like soil and vegetation. During the day, these materials soak up solar radiation, and at night, they slowly release that stored heat, keeping the city warmer. Another contributing factor is the lack of vegetation. Trees and green spaces provide shade and also cool the air through a process called evapotranspiration, where water is released from leaves. In cities, we've replaced these natural coolers with buildings and roads. Additionally, human activities such as driving cars, running air conditioners, and industrial processes generate waste heat. Now, the effects of urban heat islands are significant. They can increase energy consumption for cooling, raise air pollution levels, and even affect human health. So, urban planners are increasingly looking at solutions like green roofs, reflective materials, and planting more trees to mitigate these effects. Does anyone have a question?