Accompanying changes in the Sun - Earth distance directly affect the amount of solar
radiation incident in on the Earth in different parts of the year.
At each site, Fischer set up radiometers on four buildings — two with untreated roofs and two with treated roofs — to measure the amount of
radiation incident on the roof as well as the radiation reflected off the roof.
Figure 8: Solar Radiation on a Wall — The retained water is affected by the amount of
solar radiation incident on the wall.
Where 1900 BTU is the solar
radiation incident on 1 sqft of a 70 deg sloped surface in Nov on a sunny day at 46 deg N latittude.
In the Tropics, the seasonality of the solar
radiation incident on the atmosphere is weak.
The amount of solar
radiation incident on the wall affects the liquid conductivity and vapor diffusion (Figure 7).