Luminous efficacy of direct irradiance: Variations with insolation and moisture conditions

摘要: Abstract The present work is an experimental study of the relationship between luminous efficacy direct solar radiation and following quantities: global radiation, total water vapor content (as estimated from surface dew point), zenith angle. This will contribute to development a model derive illuminance, critical component in daylighting applications, more commonly available irradiance. Direct defined as ratio illuminance varies with turbidity, content, cloud cover, geometry. Insolation conditions were parameterized by diffuse irradiance geometry earlier work. We attempt here account for atmospheric additional descriptor. has impact on directly because spectrally selective absorption indirectly aerosol scattering. An important step this includes determination instantaneous precipitable measure absorption) point temperature. latter quantity routinely measured, former not. utilization temperature estimator improves visible data. Experimental observations presented are consistent expected physical processes.