Because water is not retained in the soil
as a result of runoff from these surfaces, the
quantity of water available for evapotranspiration
is reduced. Therefore, a great deal
of incoming solar energy that would have
been used to evaporate water is instead
transformed into sensible heat (Barnes et
al., 2001). In addition, many impervious
surfaces tend to be heat-absorbing structures.
The albedo of a surface is a measure
of the incoming solar radiation that is
reflected off the surface and thus is not
absorbed and transformed into heat energy.
The albedo of urban surfaces is generally
10% lower than the albedo of rural surfaces
(Oliver, 1973).