ماهي أهمية أشعة الشمس ؟
أشعة الشمس

 at the website of the National Geophysical Data Center
, Rivington et al.
, Rivington et al.
 from مرصد باريس
: A lesson plan from the National Science Digital Library.
: Online tools for calculating Rising and setting times of Sun, Moon or planet, Azimuth of Sun, Moon or planet at rising and setting, Altitude and azimuth of Sun, Moon or planet for a given date or range of dates, and more.
 - Formulas to calculate the daylength depending from latitude and day of year.
 with a solar position and solar radiation time-series calculator; by 
 about the ASTM standard solar spectrum for PV evaluation.
 for solar spectrum at ground level in the US (latitude ~ 37 degrees).
 at .