托福听力

🎧 听力原文

Listen to part of a lecture in an environmental science class. The professor is discussing the phenomenon of urban heat islands. "Now, cities tend to be warmer than the surrounding rural areas. This is known as the urban heat island effect. There are several reasons for this. First, buildings and roads made of concrete and asphalt absorb and retain heat from the sun during the day and release it slowly at night. In contrast, rural areas have more vegetation, which provides shade and releases moisture through a process called evapotranspiration, cooling the air. Second, human activities in cities, such as driving cars and running air conditioners, generate waste heat. Third, the tall buildings in cities can block wind, reducing natural cooling. Interestingly, the temperature difference between a city and its surrounding areas can be as much as 5 to 10 degrees Celsius on clear, calm nights. This effect can have significant consequences, such as increased energy consumption for cooling and higher levels of air pollution. Some cities are trying to mitigate this by planting more trees and using reflective materials on roofs."