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.