RTI Act
Urbanization leads to micro-climate changes, particularly with regard to the thermal structure of the location. Most documented among such changes is the Urban Heat Island (UHI), which has received increasing attention during recent decades. Factors leading to the excess heat of towns are changes in the thermal characteristics of the surface, modification of the air flow patterns, reduction in evaporative cooling and heat generated by human activities.
High specific heat capacity of building materials and their emissivity changes in comparison to the natural surroundings, impervious engineered surfaces like roads and paved spaces, change in surface roughness, blockage of wind due to buildings, reduction in sky view factor and associated blockage of outgoing long wave radiation from surfaces, reduction in vegetation and associated reduction in cooling through evapotranspiration, etc., are the major factors contributing to UHI.
An Urban Heat Island (UHI) develops when urban cooling rates are lower than what would have been without urbanization. Cooling peaks around 3 to 5 hours after sunset. As night advances the cooling rates in the urban and rural sites become similar and attain steady state by midnight and then remain nearly constant until sunrise. The growth and intensity of heat island depends upon the cooling rates of urban and rural environments.
The inhomogeneous cooling rates in the urban centre and adjoining suburban area and its effect on the Urban Heat Island (UHI) in Thiruvananthapuram city in peninsular South India was investigated. Air temperature variations across the study area were recorded by mobile traverse method. Cooling and warming rates in the urban centre and suburban area were derived from stationary air temperature recorders installed at these locations. The UHI intensity at this location was 2.4oC. Significant difference in the urban and rural cooling rates was observed. The maximum cooling rate in the city centre was 1.5oC/hr and 3.4oC/hr in the rural area.
The results this study has been published in January issue of the Journal of Indian Geophysical Union
