Reference for equation used to convert radiation to equivalent evaporation.

[AtrCheema]

Can you provide the exact reference for the equation that you used to convert radiation to equivalent evaporation at following line.

BASINS/atcMetCmp/modMetCompute.vb

Line 1251 in 4356aa9

lSRadIn = aSolRad / ((597.3 - 0.57 * lTAVC) * 2.54)