The effect of pavements' temperatures on air temperatures in large cities

A semi-quantitative connection between the albedo of pavements and its effect on the diurnal variation of air temperature in large cities is presented. Measurements of albedos and temperatures of a variety of asphalt concrete pavements in the eastern San Francisco Bay Area of California were made. The albedos correlate with pavement age. The time dependence of the pavement temperature is measured and calculated. Measurements show that the albedo of a chip-seal is about 70% of the albedo of the aggregates from which it is constructed. A formula to approximate the reduction of the peak air temperature by higher albedo pavement is derived and compared favorably to simulations.