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 cooling through evapotranspiration. Interestingly, the heat island effect can vary within a city. For example, parks and green roofs can create cooler pockets, while dense downtown areas with tall buildings can trap heat. This happens because buildings block wind and create canyons that prevent heat from escaping. Researchers have found that the temperature difference between a city center and its outskirts can be as much as 10 degrees Celsius on clear, calm nights. To combat this, some cities are adopting reflective materials for roofs and pavements, and increasing tree canopy. These measures not only reduce temperatures but also lower energy consumption for air conditioning, which in turn cuts greenhouse gas emissions. So, the urban heat island is not just a comfort issue; it has real environmental and economic implications.