Geoscience Reference
In-Depth Information
Figure 2.9.
Frequencies for the 13 different altitude classes in France (8,833,676 pixels)
and for the 115 climatological stations which record duration of sunshine
a)
a)
b)
b)
Figure 2.10.
Maps showing zones in which it is possible and in which
it is impossible to carry out the interpolation of duration of sunshine,
according to the a) criteria of altitude, and b) altitude and slope
These restrictions are much more severe as far as slope is concerned: no
sunshine station was found at a slope of more than 5°. Interpolation based on
altitude limits the field of interpolation to altitude levels lower than 1,020 m (Figure
2.10a). If we consider interpolation based on altitude and slope, then the field of
interpolation becomes narrow as it then becomes impossible to carry out the process
of interpolation on slopes of more than 5° (Figure 2.10b). If altitude is considered as
being a factor that does not have much effect on the duration of sunshine in summer
(r = 0.2), then the slope of a mountain is considered as having a slight effect on the
duration of sunshine in summer (r = 0.46). Under these conditions, the correlation
