Discrimination of insolation conditions considering cie standard for general sky

摘要

This study introduces a method to classify insolation conditions by the values of insolation indices. Number of sky types and combination of insolation indices to classify sky types were investigated. Fifteen insolation condition groups were clustered regarding nine indices by nearest centroid sorting method. Then groups were put together into sky types from clear to overcast by considering the frequency distributions of both sky luminance distribution types for groups and insolation groups for luminance types. Seven sky types were found as a result.Indices to discriminate next sky types were found and then the most appropriate combination for total discrimination was decided : turbidity, clearness index, brightness and normalized global illuminance. Sky type discrimination tree on the basis of the value of the indices was formed by a yearly data of IDMP Kyoto station and verified by the data of another year. Insolation conditions can be separated into seven sky types by the ranges of four indices.