Cloud cover and horizontal plane eye damaging solar UV exposures.
The spectral UV and the cloud cover were measured at intervals of 5 min with an integrated cloud and spectral UV measurement system at a sub-tropical Southern Hemisphere site for a 6-month period and solar zenith angle (SZA) range of 4.7 degrees to approximately 80 degrees . The solar UV spectra were recorded between 280 nm and 400 nm in 0.5 nm increments and weighted with the action spectra for photokeratitis and cataracts in order to investigate the effect of cloud cover on the horizontal plane biologically damaging UV irradiances for cataracts (UVBE(cat)) and photokeratitis (UVBE(pker)). Eighty five percent of the recorded spectra produced a measured irradiance to a cloud free irradiance ratio of 0.6 and higher while 76% produced a ratio of 0.8 and higher. Empirical non-linear expressions as a function of SZA have been developed for all sky conditions to allow the evaluation of the biologically damaging UV irradiances for photokeratitis and cataracts from a knowledge of the unweighted UV irradiances.
Parisi
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AV
Centre for Astronomy, Solar Radiation and Climate, University of Southern Queensland, 4350 Toowoomba, Australia. parisi@usq.edu.au
Downs
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N
D001272:Atmosphere; D002386:Cataract / Q000209:etiology*; D004781:Environmental Exposure; D004784:Environmental Monitoring; D005123:Eye / Q000473:pathology; D006801:Humans; D007634:Keratitis / Q000209:etiology*; D014466:Ultraviolet Rays / Q000009:adverse effects*; D014867:Water
D014867:Water