雅思听力

🎧 Listening Transcript

Today in our environmental science lecture, we'll discuss urban heat islands. These are areas in cities that are significantly warmer than surrounding rural areas. The main cause is the replacement of natural surfaces with concrete and asphalt, which absorb and retain heat. Additionally, lack of vegetation reduces shade and evapotranspiration. A key study in Phoenix, Arizona, found that installing reflective roofs on buildings could lower city temperatures by up to 2 degrees Celsius. However, researchers noted that planting more trees in residential neighborhoods had a greater effect on reducing nighttime heat, because trees release moisture and block longwave radiation. This is why many city planners now prioritize green spaces over reflective surfaces.