Causes Of Heat Islands
Many buildings found in urban areas have dark surfaces. Dark surfaces absorb more light energy, and heat, making the entire building warmer. Buildings with brick walls or roofs, if coated with dark coatings, also get heated up very quickly. In both cases, this heat is transferred both inside the structure and radiated into the surrounding air.
Buildings with dark surfaces heat up more rapidly and require more cooling from air conditioning, which requires more energy from power plants, which causes more pollution. Also air conditioners exchange heat with atmospheric air, causing further local heating. Thus there is a cascade effect that contributes to the expansion of urban heat islands.
Asphalt and concrete, needed for the expansion of cities, absorb huge amounts of heat, increasing the mean surface temperatures of urban areas. Tall buildings, and often, accompanying narrow streets, hinder the circulation of air, reduce the wind speed, and thus reduce any natural cooling effects.
Expanded transportation systems and the unimpeded use of fossil fuels also add warmth to urban areas.