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. This happens because concrete, asphalt, and buildings absorb and re-emit solar heat more than natural landscapes do. Also, waste heat from vehicles and air conditioners adds to the effect. But there are strategies to mitigate it. One common approach is increasing vegetation—planting trees and creating green roofs. Trees provide shade and release moisture through transpiration, which cools the air. Another strategy involves using reflective materials on rooftops and pavements, often called 'cool roofs' or 'cool pavements.' These materials reflect more sunlight and absorb less heat. However, implementing these solutions isn't always straightforward. For instance, green roofs require structural support and ongoing maintenance, while cool pavements may be more expensive initially. City planners must weigh costs and benefits. Interestingly, even small changes—like planting street trees—can have a noticeable impact on local temperatures. So, while urban heat islands are a serious issue, targeted interventions can make a difference.