Sumy dzienne promieniowania słonecznego w okresie letnim w Felinie koło Lublina i ich związek z usłonecznieniem i zachmurzeniem

The paper presents the relationships between daily sums of global solar radiation and real sunshine duration and separately, mean for a day amount of total cloudiness (computed from three standard observation terms) within 11 May – 31 July period in Felin. This period is approximated to the insolation summer one and is characterised by a long day (at least 15.5) and slight differentiation in time. The relationships were obtained on the basis of mean decade data and a stretch of single days during fi ve seasons (but not successive). They were described with two types of equation regressions: linear and curvilinear (a 2-degree polynomial). Additionally, the same relationships were determined regarding the days without and with precipitation during the examind summer periods. The analysis performed in relation to effectiveness of each of these equations application to estimate daily sums of global solar radiation (the relative and standard errors) showed that better results are obtained from the equations concerning relations of the solar radiation with sunshine duration than cloudiness. It also reveated that to describe both types of the relationships, a polynomial is more effi cient than linear regression (particularly in the case of daily data examination). Moreover, it was stated that determination of these relationships for some specifi c days (eg. days without precipitation) is appropriate as it allws to estimate the daily sum of solar radiation with smaller errors.