Abstract
This study is to describe the degradation behavior of the optical constants ( refractive index n and extinction coefficients) of PE-LD sheets during exposure to an arid climate. Values of n and s are used to determine the solar radiative properties of any PE-LD cover at any time without the need of measurements. Different greenhouse models were covered with PE-LD films and exposed for 1 year to an arid climate, and values of n and s were investigated. Exposing films to the arid climate for 1 year increased the values of n from 1.58 to 2.86 and s from 3.86 to 8.1 mm -1, resulting in a decrease in transmittance from 0.42 to 0.12. Two correlations for predicting the degradation rate of n and s for PE-LD covers were developed.