How does the temperature of urban areas like Atlanta, Philadelphia, and Chicago differs from that of surrounding rural areas?

The term "urban heat island" refers to the phenomenon where temperatures in large cities are higher than in rural areas nearby.

The primary cause is that artificial covers, like paved roads, alter the land's surface and increase its absorption of solar radiation by lowering the land's albedo, or reflective power.

Additionally, the presence of buildings, particularly tall ones like skyscrapers, alters the patterns of wind circulation within cities; in general, wind speed is decreased (with a few exceptions made when buildings create venturi effects, which cause the air flow to accelerate locally due to the narrowing space between the buildings), allowing heat to be retained.

Finally, the use of energy in cities (cars, air conditioning, lights, heat loss from heated buildings) results in some heat being produced.

An average of five degrees Celsius can be found between the recorded temperature in a large city and the surrounding rural area.

Urban areas like Atlanta, Philadelphia, and Chicago tend to have higher temperatures compared to surrounding rural areas due to the urban heat island effect. This effect is caused by human activities such as the construction of buildings, roads, and other infrastructure, which absorb and retain heat. Additionally, the presence of large amounts of concrete and asphalt surfaces, as well as reduced vegetation, leads to less evapotranspiration and higher temperatures in urban areas.