Ground based measurements of atmospheric infrared radiation from clear and cloudy skies.

This thesis presents results for the infrared (IR) sky temperature measurements using IR thermopile detectors (wavelength peak at 10 µm) at 6 locations around the globe: Adelaide; Australia, Riyadh, Jeddah, Abha and Tabouk; Saudi Arabia, and the Piere Auger observatory site; Argentina. Based on these measurements empirical models for predicting hourly night-time IR sky temperatures clear skies have been developed. These models showed very good performance and better prediction to the measured sky temperatures. Some of these new models showed excellent predictive power for the presence of the cloud over the site. It was found that under some extreme conditions other factors, e.g. aerosols, have great influence on the atmospheric radiation and need to be accounted for. MODTRAN software was used to give the theoretical justifications for the proposed models and was used to investigate some of these factors. A unified model for clear sky temperature from all the sites was found. The applicability of some existing clear sky models to the sites was also tested. While some of them were adequate for estimating IR sky temperatures, others were not.Thesis (Ph.D.) -- School of Chemisty and Physics, 2007