# Geographical Distribution of Global Radiation and Sunshine Duration over the Island of Cyprus
## 3 Results and Discussion
### Daily Values
#### 3.1.4 Statistical Relationships  
The linear relationship between the daily clearness index (\(K_{T}\)) and the daily relative sunshine duration (\(\sigma\)) for Kambos is shown in Figure 14a, while the relationship between the daily global radiation (\(G_{d}\)) and the daily sunshine duration (\(S_{d}\)) is also expressed as a quadratic equation as shown in Figure 14b. Similar relationships were obtained for the other stations that measure global and sunshine duration. Both equations are associated with high coefficients of determination (Table 8a). The residuals (the difference between the observed and estimated data) are normally distributed and the plots of residuals versus the fitted values show no obvious patterns or clusters suggesting that the assumption of constant variance has not been violated (not shown here). The standard error of the residuals (S) is shown on the legend of the graph. In the case of the linear equations (\(K_{T}\) vs. \(\sigma\)), the intercept ranged between 0.100 and 0.280, while the slopes ranged between 0.455 and 0.700. The sum of the intercept and the slope indicates the amount of global radiation reaching the ground on a clear day. The average sum of the constants of all the sites was 0.788. Table 8b presents the linear equations of the monthly means of daily values.  
\begin{table}
\begin{tabular}{c c c c c c c c c} \hline \multicolumn{3}{c}{**Relative Sunshine (\(\sigma\))**} \\ \hline  & \multicolumn{2}{c}{**Pentakomo**} & \multicolumn{2}{c}{**Athalassa**} & \multicolumn{2}{c}{**Kambos**} & \multicolumn{2}{c}{**Agros**} \\ \hline
**Month** & **Mean** & **StDev** & **Mean** & **StDev** & **Mean** & **StDev** & **Mean** & **StDev** \\ \hline
**1** & 0.634 & 0.266 & 0.510 & 0.260 & 0.530 & 0.281 & 0.485 & 0.268 \\
**2** & 0.697 & 0.289 & 0.708 & 0.240 & 0.589 & 0.280 & 0.554 & 0.264 \\
**3** & 0.721 & 0.276 & 0.654 & 0.253 & 0.632 & 0.265 & 0.684 & 0.233 \\
**4** & 0.769 & 0.216 & 0.691 & 0.276 & 0.701 & 0.234 & 0.714 & 0.202 \\
**5** & 0.871 & 0.102 & 0.868 & 0.091 & 0.826 & 0.144 & 0.715 & 0.166 \\
**6** & 0.868 & 0.096 & 0.868 & 0.118 & 0.826 & 0.108 & 0.735 & 0.129 \\
**7** & 0.896 & 0.026 & 0.912 & 0.043 & 0.871 & 0.046 & 0.788 & 0.077 \\
**8** & 0.911 & 0.042 & 0.920 & 0.039 & 0.878 & 0.049 & 0.808 & 0.092 \\
**9** & 0.910 & 0.037 & 0.892 & 0.068 & 0.795 & 0.102 & 0.789 & 0.121 \\
**10** & 0.861 & 0.173 & 0.815 & 0.123 & 0.762 & 0.187 & 0.730 & 0.179 \\
**11** & 0.729 & 0.226 & 0.501 & 0.284 & 0.641 & 0.266 & 0.631 & 0.232 \\
**12** & 0.607 & 0.288 & 0.572 & 0.272 & 0.563 & 0.246 & 0.521 & 0.255 \\ \hline
**Year** & 0.793 & 0.219 & 0.748 & 0.246 & 0.720 & 0.233 & 0.688 & 0.215 \\ \hline \end{tabular}
\end{table}
Table 7: Monthly means and standard deviation of relative sunshine (\(\sigma\)) of stations representing the four classification groups.  
Figure 14: (a) Linear relationship between the daily clearness index (\(K_{T}\)) and the daily relative sunshine duration (\(\sigma\)) and (b) quadratic relationship between the daily global radiation (\(G_{d}\)) and the daily sunshine duration (\(S_{d}\)) for Kambos.