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 asphalt and concrete, which absorb and retain heat. Another factor is the lack of vegetation, which normally provides shade and cools the air through evapotranspiration. Additionally, waste heat from vehicles and air conditioners adds to the effect. To mitigate this, cities are adopting strategies like green roofs, which are covered with plants, and cool pavements that reflect more sunlight. Some urban planners also promote increasing tree canopy, as trees can lower surface temperatures by several degrees. However, these solutions require careful consideration of local climate and maintenance costs. For example, green roofs may need extra structural support and irrigation systems, especially in dry regions. Despite challenges, many cities have seen measurable benefits, including reduced energy consumption and improved air quality. So, the key is to adapt these strategies to the specific urban environment.