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Narrator: Listen to part of a lecture in an environmental science class. Professor: Today we're going to talk about a phenomenon called 'urban heat island.' Essentially, cities tend to be warmer than the surrounding rural areas. Why is that? Well, several factors contribute. First, buildings and roads made of concrete and asphalt absorb and retain heat during the day, then release it slowly at night. Second, there's less vegetation in cities, which means less shade and less cooling through evapotranspiration. Third, human activities—like driving cars, running air conditioners, and industrial processes—generate waste heat. Interestingly, the temperature difference is more pronounced at night and in winter. This warming can lead to increased energy consumption for cooling, which in turn raises greenhouse gas emissions. One solution is to increase green spaces, like rooftop gardens, which can help cool the air and reduce stormwater runoff. Another is to use reflective materials for roofs and pavements. So, urban planning can play a critical role in mitigating this effect.