TOEFL 듣기

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Listen to part of a lecture in an environmental science class. The professor is discussing the concept of 'urban heat islands.' Professor: So, we've talked about how cities tend to be warmer than surrounding rural areas. This is known as the urban heat island effect. But why does it happen? First, buildings and roads absorb and re-emit solar energy more than natural landscapes do. Concrete and asphalt have high thermal mass, meaning they store heat during the day and release it slowly at night. Second, there's a lack of vegetation. Trees and plants provide shade and cool the air through evapotranspiration. When we replace them with impervious surfaces, we lose that cooling mechanism. Third, waste heat from vehicles, air conditioners, and industrial processes adds to the overall temperature. Now, a common misconception is that urban heat islands are only a daytime phenomenon. Actually, the temperature difference is often greatest just after sunset, because rural areas cool down faster, while city surfaces continue to radiate stored heat. So, the effect can be more intense at night in many cases.