UniSky Simulator:

UniSky Simulator can model radiance patterns for various cloud configurations, including regular cloud arrays, randomly distributed clouds as well as statistical averaging over random distributions. The tool is publicly available here (the ratio of vertical/horizontal irradiances or illuminances is computed now - see "Wall Spectral Irradiance" in result window. To download the previous version 1.1 click here . If you choose to use the freeware, please send an email to kocifaj@savba.sk ''registering'' as a user.

However, if you use UniSky Simulator, we request that you reference some of the papers on which UniSky Simulator is based:

• Kocifaj, M. (2015). Unified system of radiance patterns under arbitrary sky conditions. Solar Energy 115, pp.40-51.
• Kocifaj, M. (2012). Angular distribution of scattered radiation under broken cloud arrays: An approximation of successive orders of scattering. Solar Energy 86, pp. 3575-3586.
• Kocifaj, M., Lukáč, J. (1998). Using the multiple scattering theory for calculation of the radiation fluxes from experimental data. J. Quant. Spectrosc. Radiat. Transfer 60, pp. 933-942.
• Kocifaj, M. (2009). Sky luminance/radiance model with multiple scattering effect. Solar Energy 83, pp. 1914-1922.
• Kocifaj, M. (2011). The influence of ground reflectance on the overcast sky luminance. Lighting Res. Technol. 43, 45-54.
• Kocifaj, M., Kómar, L. (2016). Modeling diffuse irradiance under arbitrary and homogeneous skies: Comparison and validation. Appl. Energy 166, 117-127.

The next version is under tests and will be released soon. Among many new features, the vertical-to-horizontal irradiances or illuminances can be computed for non-static inhomogeneous cloud arrays.