Calculation of Solar Illumination

Abstract

Solar radiation is the most disturbing external heat source. With solar radiation incident on the ground between approximately 300 and 1000Wm^-2, a white painted telescope or enclosure surface will absorb approximately 50–300Wm^-2. This power will heat up the surface, but part of the absorbed power is radiated back into the environment at infrared wavelengths. The actual amount of incident and absorbed radiation depends on the shape of the telescope and enclosure surface, its orientation towards the Sun, and its surface finish. This chapter explains the calculation of the solar illumination for several telescope components and enclosures.