การฟัง TOEFL

🎧 บทถอดเสียง

Narrator: Listen to part of a lecture in an environmental science class. Professor: Today we're going to talk about urban heat islands, a phenomenon where cities are significantly warmer than surrounding rural areas. One major cause is the replacement of natural surfaces with materials like concrete and asphalt, which absorb and retain heat. Another factor is the lack of vegetation, since trees and plants provide shade and release moisture through evapotranspiration, cooling the air. Additionally, waste heat from vehicles, air conditioners, and industrial processes adds to the effect. Interestingly, the intensity of an urban heat island can vary within a city. For example, densely built downtown areas may be several degrees warmer than nearby parks or residential neighborhoods with more trees. This variation has practical implications. Higher temperatures increase energy demand for cooling, which in turn raises greenhouse gas emissions. They also exacerbate health risks during heat waves, particularly for vulnerable populations. To mitigate these effects, some cities are implementing green roofs, planting more street trees, and using reflective materials on buildings and pavements. These strategies not only reduce temperatures but also improve air quality and stormwater management. Now, let's consider a case study...