Clearness indices Global and ultraviolet B radiation clearness index 1 Mean bias errors 1 Mean square error 1 Ratio of ultraviolet B radiation to broadband G 1 Root mean square errors 1 Solar radiation 1 Ultraviolet B radiation 1 Ultraviolet B radiations 1 Zenith angle 1 global and UVB clearness indices 1 global solar radiation 1 ratio of UVB to broadband G 1 ultraviolet B radiation (UVB) 1 zenith angle 1