What Is the Urban Heat Island Effect?
Sourced from Planetizen
The urban heat island effect refers to the accumulated impact of buildings, roads, and other human-built structures that absorb the sun’s heat more than natural surfaces such as grass, soil, and trees and raise the surrounding air temperature.
First identified in the early 1800s and named in 1929 by Albert Peppler, the effect has grown more powerful as urbanization claims more undeveloped land and surfaces such as asphalt become ubiquitous in human settlements around the world, making some cities significantly warmer than surrounding rural and natural areas. The effect can also have noticeably different impacts on neighborhoods within the same city based on tree cover, green space, urban geometry, and building materials. Man-made surfaces retain heat longer, so urban areas also stay warmer for longer even after the sun sets.
According to the Environmental Protection Agency (EPA), heat islands can form due to several factors: the reduction of natural landscapes, building materials that absorb more heat than natural surfaces, the size and shape of buildings (which can influence wind flow), heat generated by appliances, cars, and other human activities, and weather and geography. Tall buildings can create ‘urban canyons’ that trap warm air and reduce air flow.
The EPA defines two types of heat islands. Surface heat islands are created when surfaces like asphalt absorb and emit heat at higher rates than natural surfaces such as grass. Atmospheric heat islands are a broader phenomenon formed when air in one area is warmer than in surrounding areas, such as a city being warmer than surrounding countryside.
From the Living Architecture Monitor
