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 urban heat islands. As you know, cities tend to be warmer than surrounding rural areas. This is mainly because concrete and asphalt absorb and re-radiate heat, while vegetation and soil in rural areas provide cooling through shade and evapotranspiration. But there's a lesser-known factor: the shape of the city itself. Tall buildings create canyons that trap heat, especially at night. However, cities can mitigate this effect. One strategy is increasing albedo, or reflectivity, by painting roofs white or using reflective materials. Another is planting more trees and creating green roofs. But these solutions have limitations. For instance, white roofs work well in sunny, hot climates but are less effective in cloudy or cold regions. So, urban planners must consider local climate and building density. This is where our next topic, climate modeling, becomes useful. Models can predict how different designs affect temperature distribution. Now, let's look at a case study from Phoenix...