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. "Urban areas tend to be warmer than surrounding rural areas, a phenomenon known as the urban heat island effect. This occurs because cities are covered with concrete, asphalt, and buildings that absorb and retain heat during the day and release it slowly at night. In contrast, rural areas have more vegetation and soil, which provide shade and moisture through evapotranspiration. Several factors intensify this effect. First, the dark surfaces of roads and rooftops have low albedo, meaning they reflect little sunlight and absorb a lot of heat. Second, waste heat from vehicles, air conditioners, and industrial processes adds warmth. Third, the lack of trees reduces shading, allowing more solar radiation to reach the ground. Interestingly, the intensity of the heat island can vary by season and time of day. It is usually strongest on clear, calm nights, when the heat stored in buildings and pavement is released into the air, while rural areas cool off quickly. To mitigate this effect, cities are adopting strategies such as green roofs, planting street trees, and using reflective materials for pavements."