"A Heat Island" is an area where the ambient temperature is higher than the surrounding temperature. The high temperature will increase the demand of electricity for refrigeration and air conditioning to increase the production of carbon dioxide and other pollutants. These pollutants will eventually play a role in rising global urban temperatures.
Urban Heat Island phenomenon is characterized by spatial and temporal variations related to climate, topography, physical layout and short-term weather conditions. Urban Heat Island is very strong pattern is controlled by the unique characteristics of each city. Factors that influence the Urban Heat Island effect them;
- Geometry of the hallway that lowers radiation shortwave radiation due to the displacement of the alley way between buildings and complex filtering the sky. Infrared radiation emitted from a variety of buildings and the road surface.
- The nature of the heat storage material that increases the sensible heat to the surface of the city during the day and release heat to the atmosphere of the city at night.
- The release of heat from fuel combustion from vehicles or other sources and animal metabolis
- The greenhouse effect that contributes to increase the acceptance of long-wave radiation from atmospheric-polluted city.
- Decrease in surface evaporation in the city led to increased sensible heat and latent heat decrease.
Some studies show a direct relationship between density and population of a city and the intensity of the Heat Island effect. Urban land use and the closure of the surface also influences the Urban Heat Island effect. Temperatures in the city center where there is usually a function - the function of commercial and office with the closing of the land, recorded higher than other functions. Hashim and Nugroho, 2003, reported that the temperature in the center of Malang with office and commercial functions, higher than the surrounding area. Research conducted Stabler, 2005, in the state of the United States Phoenics also shows that urban microclimate associated with land use.
