Listen to part of a lecture in an environmental science class. Professor: Today we're going to discuss a concept that's crucial to understanding urban heat islands—albedo. Albedo is the measure of how much solar radiation a surface reflects. Surfaces with high albedo, like fresh snow, reflect most incoming sunlight, while dark surfaces, like asphalt, have low albedo and absorb more heat. In cities, rooftops and pavements are often dark, which contributes to higher temperatures compared to surrounding rural areas. One proposed solution is to increase the albedo of urban surfaces by painting rooftops white or using reflective materials. Studies show that cool roofs can reduce a building's cooling demand by up to 20 percent, but the effectiveness depends on climate. In hot, sunny regions, the benefits are substantial, but in cooler climates, the impact is less noticeable. Additionally, reflective pavements can reduce the heat absorbed during the day, but they may cause glare for drivers. So while albedo modification is promising, urban planners must weigh these trade-offs carefully.
❓ Question What is the main point the professor makes about albedo?
A. Albedo is the primary cause of rural temperatures being lower than urban ones.
B. Increasing albedo can reduce urban heat, but its effectiveness varies by location and has drawbacks.
C. Cool roofs are the most effective solution for all climates.
D. Reflective pavements are always better than dark pavements.
✅ Correct Answer
Increasing albedo can reduce urban heat, but its effectiveness varies by location and has drawbacks.
TOEFL Listening Tips
Skim the questions first to predict the content
Watch for signal words in lectures and conversations (however, actually, in fact)
For main idea questions, focus on the beginning; for detail questions, focus on examples and data
For attitude questions, pay attention to the speaker's tone and word choice
Take notes on keywords; don't try to write down every word