การฟัง TOEFL

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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 heat more than natural landscapes like trees and soil. But there's an interesting solution that's gaining traction: green roofs. These are roofs covered with vegetation, and they can reduce surface temperatures by up to 40 degrees Celsius. How? Plants provide shade and release moisture through transpiration, which cools the air. Also, the soil acts as an insulator. Beyond temperature, green roofs manage stormwater by absorbing rainwater, reducing runoff and the risk of flooding. They also improve air quality by filtering pollutants. However, there are challenges. The initial cost is higher than traditional roofs, and they require regular maintenance, including watering and weeding. Despite these costs, many cities now offer incentives to encourage green roof installation. So, while not a one-size-fits-all solution, green roofs offer multiple environmental benefits.