## 3 Results
### Annual Maps of Sky Status  
This section is devoted to the depiction of the dispersion of the sky conditions over Greece. Indeed, Figure 8 show the distribution of the clear-, intermediate-, and overcast-sky events as annual values of the TMYs across the 43 sites. Figure 8a shows the distribution of the clear-sky conditions over Greece. It is apparent that higher SSD values occur in the southern part of Greece, i.e., below the geographical latitude of 39\({}^{\circ}\). In other words, the country can be divided into two parts, northern and southern as far as SSD is concerned. The pattern for overcast skies in Figure 8c presents an opposite pattern to that for clear skies, i.e., greater number of sunshine hours in the northern part of Greece in comparison with that for the southern half; this is in agreement with the regression curve for the DOS cases shown in Table 4: decreasing ASI with latitude results in cleaner atmosphere, which permits more solar radiation to reach the surface. The pattern for intermediate-sky conditions is shown to be between those for clear and overcast conditions. Higher DIS values occur in the southern Aegean and southern Ionian Seas with secondary peaks over central and north-western Greece. In viewing these results as ASI, one can refer to the map of Figure 11a in [41], where the solar flux on flat-plate surfaces tilted at 25-30\({}^{\circ}\) to south presents exactly the same pattern with that of Figure 8a of the present work; this would be anticipated since lower ASI results in higher solar radiation reaching the surface of the Earth, and higher ASI blocks a significant amount of solar radiation to be incident on the flat-plate surfaces. On the other hand, Figure 12b in [42] shows the distribution of the Linke turbidity factor (T\({}_{\text{L}}\)) over Greece under clear-sky conditions. T\({}_{\text{L}}\) represents the total attenuation of solar radiation. It is seen that the T\({}_{\text{L}}\) pattern is just the opposite that for \(\text{SSD}_{\text{CS}}\) in Figure 8a of the present study; indeed, higher atmospheric turbidity (higher attenuation of solar radiation) results in lower levels of solar flux on the surface of the Earth, and, consequently, fewer sunshine hours. Now, one might wonder what the distribution of the SSD sky conditions over Greece would be like by applying the proposed model of the previous section, i.e., \(\text{SSD}_{\text{m}}=\text{DCS}+\text{DIS-1}+\text{0.8}\times\text{DIS-2}+ \text{0.5}\times\text{DIS-3}\) (the subscript m denotes model). To accomplish this, the \(\text{k}_{\text{d}}\) events in the various ranges (DCS, DIS-1, DIS-2, DIS-3) were counted and calculations according to the formula were made. Then annual mean \(\text{SSD}_{\text{m}}\) values were derived. Figure 9 shows their distribution over Greece. The resemblance of this pattern \begin{table}
\begin{tabular}{l l l l l l l} \hline \hline
**Site** & **SSD (h)** & **DCS (h)** & **DIS-1 (h)** & **DIS-2 (h)** & **DIS-3 (h)** & **Difference (h)** \\ \hline Chisinau, ASM & 2346 & 1203 & 778 & 511 & 0 & \(-\)71.1 \\ Elliniko, DWD & 2905 & 1523 & 813 & 481 & 239 & 64.7 \\ Irakleio, DWD & 2905 & 1548 & 804 & 506 & 297 & \(-\)0.3 \\ Kerkyra, DWD & 2593 & 1240 & 892 & 462 & 351 & \(-\)84.1 \\ Larissa, DWD & 2435 & 1185 & 864 & 495 & 264 & \(-\)142 \\ \hline \hline \end{tabular}
\end{table} 
Table 6: Annual mean values of SSD from DWD, ASM, and DCS, DIS-1, -2, -3 from this work. The difference in the last column is expressed as \(\text{SSD}-\text{SSD}_{\text{m}}=\text{SSD}-(\text{DCS}+\text{DIS-1}+\text{0.8} \times\text{DIS-2}+\text{0.5}\times\text{DIS-3})\) for the five sites of Table 5. DIS-1 corresponds to the \(\text{k}_{\text{d}}\) counts in the interval (0.26, 0.43), DIS-2 to (0.43, 0.60], and DIS-3 to (0.60, 0.78]. with that of Figure 8a is remarkable, at least quality-wise; there are, of course, differences in the individual values between the two Figures, the cause of which has been discussed in the previous section.