Abstract
The purpose of this research is to examine the actual conditions of daylight and solar radiation and to analyze the relationship of these to clouds. Global horizontal illuminance and irradiance increase with increasing solar altitude, and decrease with increasing cloud amount except in the case of high clouds. High clouds have no substantial influence on changes of global horizontal illuminance and irradiance. Diffuse horizontal illuminance and irradiance increase with increasing solar altitude, and increase with increasing cloud amount. Global horizontal illuminance/irradiance ratio increases slightly with increasing cloud amount. Diffuse horizontal illuminance/irradiance ratio decreases with increasing cloud amount.
