THE MIDDLE ULTRAVIOLET REACHING THE GROUND*

Abstract

Abstract— We present a semi‐empirical analytic formula for calculating the direct, diffuse and global solar middle‐ultraviolet radiation (280–340 nm) reaching the ground. The formula accommodates variations in wavelength, solar angle, ozone thickness, aerosol thickness, ground albedo, ground elevation, and cloudiness. Analytic representations of biological action spectra are also presented for use in calculations of effective dose at any time of day. Our purpose is to provide a basis for estimating approximate changes in middle‐ultraviolet radiation levels reaching the ground caused by anthropogenic changes in the intervening atmosphere.