Abstract:

In order to develop the technical measures to alleviate the heat island effects in Changsha City, data set collected with method of test and investigation was analyzed the causes of heat island effects in urban area of Changsha City. The results showed that: urban heat island effect intensity was enhanced with the construction of the expansion of urban areas, and the scope and expansion trend of heat island effect was consistent with construction and development of urban areas; internal structure within the urban and urban surface characteristics of thermal properties was the basic foundation of urban heat island effects; artificially increasing the urban heat, which increased the urban heat in the atmosphere, promoted the formation of urban heat island effect; emissions of air pollutants and dust, adopting the ‘dust cover’ or ‘hood’ in the form of low coverage layer in atmosphere air, enabled the heat island effect through blocking long-wave radiation from the earth surface and, in turn, increasing the atmospheric long-wave radiation to the ground; weather and climate conditions played an important role in the presence of Changsha urban heat island effects. Changsha urban heat island effect generally happened in the conditions of sunny, no wind (or breeze), stable atmospheric stratification, and weak air turbulence. On the contrast, the heat island phenomenon of Changsha City did not happen under weather conditions of severe vertical movement of air, or duration of rainfall, precipitation, or earth surface wind speed over 4 m/s.