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.
❓ 根据讲座内容，凤凰城的研究揭示了白色屋顶的哪些情况？
A. A) 它们降低气温的幅度大于降低地表温度的幅度。
B. B) 它们对地表温度的影响大于对气温的影响。
C. C) 在降低行人高温方面，它们比街道树木更有效。
D. D) 它们对城市气温没有显著影响。
✅ 正确答案
B) They had a greater effect on surface temperature than on air temperature.