“…These methods are based on empirical modelling related to variables such as temperature Bristow and Campbell, 1984;Donatelli and Campbell, 1998;Goodin et al,1999;Mahmood and Hubbard, 2002;Benghanem and Mellit, 2014), sunshine duration ( Angstrom, 1924;Prescott, 1940;Al-Mostafa et al, 2014;Despotovic et al, 2015;Lockart et al, 2015;Teke et al, 2015), rainfall ( McCaskill, 1990;Liu and Scott, 2001;Chen et al, 2006;Wu et al, 2007;Kirmani et al, 2015), cloudiness ( Supit and van Kappel, 1998;Gu et al, 2001;Badescu, 2002), elevation (Allen, 1995;Winslow et al, 2001;Annandale et al, 2002), humidity (Gu et al, 2001;Chen et al, 2006;Almorox et al, 2011;Li et al, 2013;Antonanzas-Torres et al, 2013;Li et al, 2015) and latitude (Toğrul and Onat, 1999;Skeiker, 2006). Several studies have shown that the best performing models use sunshine duration data, followed by those utilizing cloudiness and then temperature data (Bakirci, 2009;Chen and Li, 2013).…”