雅思听力

🎧 Listening Transcript

Today in our environmental science lecture, we'll discuss urban heat islands. Cities tend to be warmer than surrounding rural areas because concrete and asphalt absorb and re-emit heat. One major factor is the lack of vegetation, which normally provides shade and cools the air through evapotranspiration. Another contributor is waste heat from vehicles and air conditioning. Interestingly, a study in Phoenix found that painting rooftops white could reduce surface temperatures by up to 20 degrees Celsius, but the effect on air temperature was smaller. However, planting trees along streets proved more effective for lowering pedestrian-level heat, especially in residential areas.