Urban climatology applied to the deterioration of the Pisa Leaning Tower, Italy

Among the peculiarities of the urban climatology, a relevant one concerns t he interactions with monuments, which include stone weathering, deposition and removal of airborne pollutants. In order to know more about the case of the Pisa Leaning Tower, Italy, a field survey has been made for one year, measuring the microclimate interacting with the structure, the vertical tem perature and humidity profiles, the Tower surface temperature at different locations and the concentration of particles in air. Also more general info rmation was collected studying the meteorological parameters in the area of Pisa. The: correlation between rainfalls and wind evidenced that the windb orne droplets arrive from preferential directions, determined on the region al scale by the sea shore on the: west (sea breeze) and the channelling ope rated by the valley of the Arno river on the west. The tilting of the Tower gives a natural shield to the southern part, which is hardly washed by rai nfall. The complex balance between airborne particulate matter deposition, tower tilting, rainfall washout and surface runoff determines the pattern o f the black crusts which disfigure the elegance of this historical building . The land and sea breezes transport air with different moisture content, a nd the urban heat island accentuates the mid day drop on relative humidity, determining condensation-evaporation cycles in the stone micropores. The u rban climatology of Pisa and the interactions with the Leaning Tower are di scussed in view of the conservation of this monument.