Nghe TOEFL

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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: Today, let's talk about urban heat islands, or UHIs. This phenomenon occurs when cities are significantly warmer than surrounding rural areas. Why? Well, one major factor is the replacement of natural surfaces with materials like concrete and asphalt. These materials absorb and retain heat during the day and release it slowly at night. In contrast, vegetation and soil in rural areas provide shade and cool through evapotranspiration. Another contributor is waste heat from buildings, vehicles, and industrial processes. Interestingly, the intensity of an urban heat island can vary depending on the city's layout, population density, and even the color of rooftops. For instance, dark roofs absorb more solar radiation, while reflective or green roofs can mitigate the effect. Some cities are adopting strategies like planting more trees and creating green spaces to combat this issue. This not only reduces temperatures but also improves air quality and reduces energy consumption for cooling. So, while UHIs are a challenge, they also present opportunities for innovative urban planning.