Urban Heat Islands (UHI) are significantly warmer urban areas than its surrounding rural areas due to human activities. Urban Heat Island is a major problem associated with rapid urbanisation. The temperature increase is attributed to deforestation and the construction materials adopted for city building. Usually, under the urban heat island phenomenon, the central regions of urban centres exhibit higher mean temperatures than the surrounding areas.
Causes for the formation of heat islands in the urban habitat of the world are as follows:
- Heat islands form in urban and suburban areas because many common construction materials absorb and retain more of the sun’s heat than natural materials in less developed rural areas. Temperatures of dark, dry surfaces in direct sun can reach 88°C during the day, while vegetated surfaces with moist soil under the same conditions might reach only 18°C.
- Concrete, cement, and metal surfaces in urban areas tend to absorb heat energy rather than reflect it, contributing to higher urban temperatures.
- Cities have a low albedo, the reflecting power of a surface. The increased surface area of buildings results in more solar radiation absorption than reflection.
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