Abstract
Exterior illuminance data recorded at regular one-minute intervals and simultaneous zenith sky luminance have been gathered as part of the International Daylight Measurement Programme. Data measured at several locations characterise luminous climate and the frequency of occurrence of typical sky patterns reflecting local variations. Zenith vector luminance has a direct influence on the resulting (scalar) horizontal diffuse/sky illuminance level. Thus their ratio usually indicates the prevailing character of the sky luminance distribution. Sophisticated parametrisation and 'bin' selection methods have been used to analyse data recorded in Bratislava, Slovakia during 1995. Examples are shown of how frequent and specific sky conditions can be identified in the absence of sky scanning and cloudiness information.
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