托福听力

🎧 听力原文

Listen to part of a lecture in an environmental science class. The professor is discussing the concept of urban heat islands. "Now, cities tend to be warmer than surrounding rural areas. This is known as the urban heat island effect. Several factors contribute to this. Buildings and roads made of concrete and asphalt absorb solar radiation during the day and release it slowly at night. In contrast, rural areas with vegetation and soil have higher albedo and also cool through evapotranspiration. Additionally, waste heat from vehicles, air conditioners, and industrial processes adds to the warmth. The lack of trees and green spaces reduces shade and limits natural cooling. Interestingly, the intensity of the heat island can vary. It is often strongest on clear, calm nights, when heat stored in urban materials is released, and weakest during windy or cloudy conditions when the air mixes or insulation occurs. Some cities are implementing green roofs and planting more trees to mitigate this effect. These measures not only lower temperatures but also reduce energy consumption, as less air conditioning is needed."