 Historic Stone Building in Downtown Philadelphia Scientists studying the degradation rates of stone materials outdoors measure and model natural and pollution-related degradation processes and their effects on buildings such as this one (Figure 7a). Notice that the structural features in Figure 7b are much sharper than those in Figure 7c, which are more rounded due to degraded edges. These types of studies require measuring the wet and dry deposition of natural and pollutant chemicals. Meteorological variables such as solar radiation, temperature, relative humidity and condensation of moisture, measured with inches of the surfaces shown in Figures 7b and 7c, are also important in understanding the rates at which surfaces degrade outdoors. Click on a photo to view a larger version. |
 Fig7a. |
|
 Fig 7b. |
||
 Fig 7c. |
||
|
|
||