Urban Heat Island

Urban areas often experience warmer temperatures than their surrounding rural areas. This phenomenon, called the urban heat island (UHI) effect, has been observed in numerous settlements around the world, making it one of best-documented examples of inadvertent climate modification. Heat islands occur in the air, at the surface, and in the ground beneath cities. Atmospheric heat islands may extend to considerable distances aloft, although UHIs occurring below roof level in the urban canopy layer have received the most attention in the literature. As an increasing proportion of the world's population lives in urban areas, cities grow, and their impact on environmental, biophysical, and atmospheric processes increases. This entry provides a brief overview of UHI impacts, describes the physical causes of UHIs, and closes with a ...