The analytic expression which sets relation between the solar altitude angle and local time at a random point of the Earth surface on a random day of a year is obtained. The obtained expression and derived relations allow one to conduct calculations of daylight irradiance and illuminance of the Earth surface in analytic form. 1. Meshkov V.V., Matveev A.B. Basics of Lighting Engineering: Study Guide for Higher Education Institutions. In 2 parts. P. 2. Physiological Optics and Colorimetry [Osnovy svetotekhniki: uchebnoye posobiye dlya vuzov: v 2 ch. Ch. 2. Fiziologicheskaya optika i kolorimetriya]. 2nd edition, revised and supplemented. Moscow: Energoatomizdat, 1989, 432 p.
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• daylight irradiance and illuminance
• Earth surface
• geocentric equatorial system
• analytic form of representation
• solar altitude angle
• local time
• geographic coordinates
• year day